Author Topic: Project Complete…2y  (Read 3277 times)

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Offline Roadrunner

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Re: Project Complete…2y
« Reply #20 on: December 04, 2019, 06:09:20 PM »
pizza looks nice.  The post way too long for my attention span.  can you do a Cliffsnotes version?

Offline stef

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Re: Project Complete…2y
« Reply #21 on: December 05, 2019, 06:01:24 AM »
Appreciate the comment about the length.  It's not a regular blog: it's about what happened in a completed 2 year project.  There will be more long and more technical posts to come.

I like your CliffsNotes idea a lot: at the end I will do a short summary / tips piece: it will be v v short !

« Last Edit: December 05, 2019, 06:10:07 AM by stef »

Offline stef

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Re: Project Complete…2y
« Reply #22 on: December 09, 2019, 04:44:40 AM »
Part five of the Pizza Project:

Predicting the End Time

How to confidently predict End Time and not need to look at the dough balls at all.  (But would you risk it ?)

As dough growth is driven by yeast growth, we can say the dough will be in the Growth Phase but will also have gone through the Lag Phase. 

So could we use a yeast Growth Rate taken from the exponential yeast Growth Phase of the graph curve to work out how long will it take for our dough to grow to x2 End Time ?  This is shown in green on the graph shown above at the end of the Part 4 post.  That’s NOT correct.  It ignores the time in the Lag Phase and mixes up a domestic dough ball measurement with laboratory yeast growth measurement.

So can we predict End Time taking account of Lag Phase ?  This is shown in red on the graph.  That’s NOT correct either, because our End Time is defined for a dough ball, not yeast.

Above is what some pizza workers have done though. 

The next attached graph does work for us: it takes a similar approach to that depicted on the last graph but for dough, and is simple.  We have only one concept called Dough Growth, not Phases, and have a Dough Growth Rate, which is whatever it takes for our dough, not a lab yeast, to double in size. 

The Dough Growth Rate is a bucket: it contains all sorts of things that at this stage we don’t want to look at, and even the “unknown unknowns”.  We just add them all together.  Others call it a black box.   

I’ve measured the Dough Growth Rate for my project pizza evenings.

My Dough Growth Rate is 0.12h-1

(Calculated from 15 “standardised” pizza sessions with Fermentation Times of between 7.5h and 13h, 62% hydration, 2.5% salt, 90% Caputo Pizzeria, 10% Spanish Strong flour 13% protein, Sierra del Segura Neval mineral water (specified later), 200g dough balls, with an end to end dough temperature of 24C, ambient temperature of around 30C).

For the 15 sessions there is a Growth Rate standard deviation 0.0057, variance 0.00003 and coefficient of variability 4.91%:  these are tight results. 

The 15 pizza sessions used to measure the Growth Rate took place after progressively “closing in” on around the right amount of IDY to use for 8 hours fermentation with my now standardised preparation process.  (Standardisation covered later: managing out errors, lack of consistency etc.)  Two months before the 15 sessions the process had been ‘frozen’ and every pizza since had the same preparation, except for two batches.  There were then 4 “closing in” sessions.  So getting to the Growth Rate has been more of a "lab experiment without a lab", and eating the results a tasty fringe benefit.

The Growth Rate above is unexpectedly constant: but if the flour blend is changed for instance, the rate changes only a little: you would expect some change given the changed nutrient blend for the yeast to work on.  I have had results up to 0.13h-1 for different blends of strong flours at 12.7% protein overall.  (Flour blends are covered later, the 12.7% protein example gave an unpleasant tough pizza).

The effect of incorporating Lag Phase and focusing on dough not yeast is to reduce Growth Rate from the typical yeast value of around 0.21h-1 at 24C by almost half for a within day fermentation.  There are other factors rolled into this reduced Growth Rate which are covered below. 

Predicting Yeast Quantity from Dough Growth Rate

Well what does this Dough Growth Rate do for my End Time?  Simples !  Say I want to have a pizza evening tomorrow and I have time to start the dough mix at 10am, and want the first pizza dough ball ready to go at 7.30pm.  Therefore I have 9.5h available for fermentation.  The percentage of IDY I will need to use to achieve a x2 dough ball growth in 9.5h is:

IDY% = 2 / (Temperature * Fermentation Time * Growth Rate)

Where the 2 used above is the x2 increase in dough ball size we want to achieve. 

This formula is absolutely valid as the Dough Growth Rate is a bucket.  It contains EVERYTHING except x2 growth (known target), Temperature (known) and Fermentation Time (known)

This gives:

IDY% = 2 / ( 24 * 9.5 * 0.12 )

IDY% = 0.0731

It works for my environment.  If you prefer say, a more “sporty” x2.25, just substitute 2.25 for the 2.

The formula can be rearranged to:

Fermentation Time = 2 / (IDY% * Temperature * Growth Rate )


Growth Rate = 2 / ( IDY% * Temperature * Fermentation Time )

These formulae are absolutely valid given that the Growth Rate “bucket” includes all sorts of features and artifacts that we do not need to concern ourselves with as we are making pizza, not World Peace.  If we do want to get into the bucket, we can selectively do that, as we will later. 

NOTE: the Growth Rate is for 24C, if you change the temperature, the Growth Rate will change.   (As a loose approximation, at 17C the Growth Rate is likely to be around 0.2 - 0.7 of the 24C value.  But that is Growth Rate for 17C, not the cooling transition from Final Dough Temperature to an actual 17C, and the warming transition back up to the 20’s before the pizza disk is formed.  That is also covered later.)

On a day to day basis these formulae work reliably.

The formulae are very sensitive to the value of Growth Rate, so I calculate using the Growth Rate to 5 decimal places, ie 0.11653 rather than 0.12.  I don’t have a problem with the sensitivity as the low standard deviation and variance indicate that the estimate is precise.  This also means a relatively small number of Growth Rate estimates are required to get a consistent Growth Rate average.

I have left the formulae as above because it may help a reader seeing what does what. 

You can measure your own growth rate for your own pizza making setup, once you know how to measure x2 with dough density: get the tub level, eyeball the dough in the tub to find the time of x2, then use the formulae above to get your times and yeast quantities.

The formulae can be simplified given the constant temperature (24C) and Growth Rate (0.11653) in my environment.  The simplified form is:

IDY% = 0.71531 / Fermentation Time. 

But is this enough ?  Definitely not.

Only a few general pics today> evolution of the log stand in the horno ( oven )  and a tasty result.


Offline stef

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Re: Project Complete…2y
« Reply #23 on: December 14, 2019, 04:52:05 AM »
Part six of the Pizza Project:

Comparisons with other workers: preamble scene setting

It’s useful to compare the results in Part 5 with the reports from others.  If you are reading this but don’t want the science and just want the pizza: I can only suggest go straight towards the end of the post. 

Before the comparison with other “pizza workers”…. those who have done the trailblazing, we need to explain why yeast growth is not the same as dough growth. 

There are 3 main areas where we can cover the differences.  The first is at the initiation of yeast Growth Phase following the Lag Phase, the second occurs only if a dough warming period is used before using the ball to form a disk, and the third area is applicable to more or less the entire dough growth period.  These comments are general, not specific to my standard dough yet.

The first area: when a yeast cell buds (multiplies) in Growth Phase, carbon dioxide (CO2) is released into the liquid phase of the dough (it is NOT gas: it remains dissolved in the dough water). 

Similar to the point when a beer or champagne stores gas in the factory, to later release it when the drink is opened and it “bubbles out”: the liquid has to “let go” of the gas when the bottle is opened. 

Eventually the CO2 level in the dough increases to reach saturation point (PCO2 the Partial Pressure of CO2), it changes phase to become gas, immediately nucleating around nearby nitrogen bubbles (nitrogen has remained as a gas in the dough because the PN2 , the Partial Pressure of nitrogen,  is very low compared with carbon dioxide, oxygen has been eaten at this point).  Temperature and air entrapment during the mix affect this too.

If the dough is now at a low temperature (such as if it may have been refrigerated / chilled from the end of dough mix through the Lag Phase) it will hold onto the carbon dioxide: for instance at 17C the dough can hold 25% more carbon dioxide in solution than at 24C.  At 10C it holds 66% more. 

So whilst from a yeast perspective the yeast is growing exponentially, from a dough perspective it may not be growing: the carbon dioxide is being stored in solution, not gassing up the dough.

Therefore all other things being equal, the point at which the dough starts to grow is later than the yeast starting to grow especially at low temperature. 

This leads to a difference between a yeast growth rate and a dough growth rate.

The second area where yeast growth is not the same as dough growth: getting ready to use the dough ball: warming up the dough. 

It’s the champagne bottle being opened: sudden gas release. Extra carbon dioxide stored at low temperature (the above point) is released into bubbles as the PCO2  decreases with rising dough ball temperature.  A dough ball which has been refrigerated does not substantially grow on taking out of the refrigerator due to new yeast activity: the dough already has the carbon dioxide stored up, it now has to release it into gas as temperature goes up.  (This is how traditional “Lagering” works with a lager beer releasing gas after cold winter storage).

So the yeast growth rate stays low with a slight rise, but the dough growth rate goes nuts: as evidenced with leoparding.

This leads to a difference between a yeast growth rate and a dough growth rate.

The third area where yeast growth is not the same as dough growth: the dough / dough ball itself. 

The subject of Gas Retention: how much carbon dioxide is retained by the growing dough ? Let’s avoid yet more science about gas permeability through Darcian materials, membranes and foams…. gas is going to leak out of the dough and not contribute to its growth.  A balloon with a pinhole leak.    Let’s cover a few issues about gas retention and leakage in dough balls (and bulk dough) below:

The surface area of the dough exposed to air will affect leakage rate: so consider a growing dough ball in a fermenting tray with a substantial exposed and crusting surface area.  Or a dough ball in a tub with only its almost crust free top exposed to high humidity air below the tub lid. Or a dough ball in a plastic bag, with nothing really exposed at all.  Oh and then if it has a coating of oil to try to seal the surface in some way. 

All I know is my dough balls in tubs, trays and plastic bags have been noticeably different in their character when starting to make the pizza disk.  Subjective for me, I’m sure there is something to this other than crust.

With an impermeable dough tub wall (plastic, glass or steel) coated with an oil layer of variable thickness….  the surface tension between the oily wall and the dough will affect bubble development, often creating exaggerated bubble nucleation due to locally reduced gas leakage: a manifestation of the “edge effect” which reduces when the diameter of the tub is increased. (Edge effect is a subject in its own right ).

A stronger dough (more / better developed gluten) will allow gas to pressurise more, gas being restrained by strong and elastic bubble walls (they still leak at some level): this reduces the dough growth at this stage, but is of great benefit at dough disc time when it can rapidly expand.  So the dough mix method is crucial, also to entrain more air for nitrogen nucleation sites.

The height of the dough mass / ball is also significant, as it is very noticeable that bubbles appear smaller at the base of the dough: being “compressed” or weighed down from above.  In bread making factories the loaf dough may be turned and cut to minimise the appearance of this.

Finally, the rate of gas production is not linear through Growth Phase: there is an initial peak, followed by decline and then growth again, due to maltose becoming available for the yeast to eat.  Also the choice of SC strain used by the yeast manufacturer to meet customer needs for slow / fast fermentation in sync with the maltose availability.  In particular the design of the yeast product will be geared towards fast high temperature fermentation in the presence of substantial amounts of yeast: not enthusiast pizza makers.

This leads to another difference between a yeast growth rate and a dough growth rate.

All of the above variables are bundled up in the Dough Growth Rate, we don’t need to have any further interest in them, except in the context below.

Comparisons with other workers.

Pizza first:

My results for  0.056% IDY at 24C give:

Fermentation Time = 2 / (IDY% * Temperature * Growth Rate )

Fermentation Time = 2 / ( 0.056 * 24 * 0.12 )

Fermentation Time = 12.4h

Calculating for november’s Golden Chalice pizza dough formula, 0.056% IDY at 24C predicts 15h (I have used the common 0.75 conversion factor for ADY to IDY, Golden Chalice is defined for ADY).


Golden Chalice Growth Rate = 2 ( 0.056 * 24 * 15 )

Golden Chalice Growth Rate = 0.1h-1

This is lower than my Rate (0.12h-1 ), but it is almost a third of the 0.287h-1 Maximum Growth Rate at 20C used in the Golden Chalice equation.  November’s 0.287h-1 is an extraordinarily high rate for SC at 20C, the literature would indicate this is more typical for 28 – 30C, or glucose.  However his use of a 0.287h-1 Maximum Growth Rate is completely masked by the constants and a sine function used in the formula.  So this dough growth formula is not actually representing a realistic growth rate, but works quite well for my data if the 0.75 ADY to IDY conversion factor is lowered to around 0.66.

Looking at the Craig TX IDY data table, using 0.056% IDY at 23.9C gives a fermentation time prediction of 8h.

My estimate falls between the Craig TX (8h) and Golden Chalice (15h) predictions.

We can also “reverse engineer” what the Craig TX Growth Rate is from re-arranging the formula and using his data of 0.056% IDY, 23.9C and 8h:

Growth Rate = 2 / ( IDY% * Temperature * Fermentation Time )

Craig TX Growth Rate = 2 ( 0.056 * 23.9 * 8 )

Craig TX Growth Rate = 0.19h-1

This is significantly higher than my Rate, it is consistent with the Craig TX adaptation of the Ganzle et al (1998) Predictive Microbiology formula with 10% Growth Rate change / 1C change leading to a Growth Rate of 0.34h-1 at 30C.  (A more reasonable Growth Rate change is 6.5% Growth Rate change / 1C overall as it is not linear, also 0.19h-1 for yeast at 23.9C is a bit low, a more typical rate would be around 0.21h-1.

Irrespective, the Predictive Microbiology model used by Ganzle, earlier workers and Craig TX, is incorrect for short fermentations as they are based on the Maximum Growth Rate alone, also for yeast not dough: the inception, maxima and expiration constants need re-defining for short fermentations.  This can be done, but as with Golden Chalice, use of a Maximum Growth Rate is not that useful.

Now industry:

Using published industrial workers results plugged into our example:

Growth Rate at 24C =  0.21h-1

Fermentation Time = 2 / (IDY% * Temperature * Growth Rate )

Fermentation Time = 2 / ( 0.056 * 24 * 0.21 )

Fermentation Time = 7.1h

An even faster fermentation than my 12.4h, but remember the above concerns yeast, not dough.

However: is something completely separate being masked: which could explain the big differences in yeast quantity used with other pizza enthusiasts and professionals ?

Time to eat.


El Caliente Pavo / Pollo / Cerdo Pizza

It is essential to char the dough well: thin dough no cornicione also works.

Base of tomato: the regular base, 70g
Tierno cheese: irregular small clumps, cut as before small bits, 85% of cheese
Emmental cheese: irregular small clumps cut, 15% of cheese
Guindillo (green chilli): medium size spread irregularly all over, fine chop, deseeded and deveined, for surprise “parcels of heat”
Sweet white onion: uniformly spread cut lengthwise fine strips, fry in Jerez vinegar (added half way through fry), 15g
Red pepper: uniformly spread, cut medium fine strips, fry to soft in Jerez vinegar, 25g
Sweet white onion: uniformly spread, cut lengthwise medium strips, fry in Jerez vinegar,  15g
Green Pepper: irregular spread, cut medium fine strips, fry in Jerez vinegar  7g
Cooked red pepper strips preserved in sweet brine, 1cm x 3cm, 20 pc spread irregularly all over: the goal is to provide a distinctively moist sweet element.
Turkey / Chicken / lean Pork thin sliced: irregular spread, 12 -15 pc, pre-BBQ’d to get charred stripes, cut medium strips 3cm long, 35 - 40g
“Queso Gran Reserva” mature hard goat, cow, sheep cheese blend: coarse chop, sprinkle, 15g
EVOO spiral.
« Last Edit: December 14, 2019, 04:53:36 AM by stef »

Offline stef

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Re: Project Complete…2y
« Reply #24 on: December 18, 2019, 09:29:33 AM »
Part seven of the Pizza Project:

Measuring Lag Phase, and the implications

To recap, what else might be at play to explain differences in yeast quantity used ?

Let’s look more at what we have:

We have a practical dough Growth Rate with two Reference points: the Start: yeast in, the End: x2.  The Growth Rate is a bucket, as we said earlier: something that we don't see into.  The Growth Rate joins the Start to the End.
I needed a third Reference: the point at the end of Lag Phase: where Growth Phase starts.  It is shown as the yellow dot on the attached graph.  We need that to separate Lag Phase from Growth Phase.  This means dipping into the Growth Rate bucket.

For any particular dough type the end of the Lag Phase ( the same as the start of the Growth Phase ) can be measured, to whatever level of accuracy you choose.  It seems like Lag Phase is a sensitive hence potentially variable period in the life of the dough, with temperature consistency being key.  Any changes, the Lag Phase will likely change. 
So I had to work out what could be measured at home that would be worthwhile: ideally to measure the start of dough growth, for a range of fermentation times and yeast contents, and be able to be used for future changes in dough and environment.

I came up with a way of measuring the start of dough growth (described in detail in the later “Measurements” part of the blog).  This involved immersing standard test doughs in a water bath, weighing everything down so it could not move using 14kg (31lb) of lead and tie wraps, using time lapse photography of the dough top surfaces, and then detecting the start of growth from the pictures using image analysis.  The dangers of being retired.

The method worked.  I made ten tests: each of 10 doughs with different yeast amounts and two dough samples for each dough for 7, 8, 9, 10, 11, 12, 28, 30, 45 and 48h fermentation periods.  Twenty sets of measurements.  The start of growth was obvious on photographs except for one dough: in the end I did not need to use the image analysis tools.  However if I further extend the fermentation time in the future beyond 48h I am confident that the tools will work.
I’ve attached three pictures of the top surface of a growing dough for information, the first an unprocessed low quality JPEG, the second the same image with basic processing, and the third a high quality analysed image.  The high quality picture is of the right hand edge area of the second photograph.

Short Fermentation periods were chosen as initially it was thought that Lag Phase might be proportionally more important there. 

Most interesting however was that after use the dough samples made "acceptable" pizzas once fully fermented out….
The Lag Time results are shown below in hours for the 10 different Fermentation times:

Total Duration h      Lag Time h

   7               1.9   
   8               2.5   
   9               2.5   
   10               2.5   
   11               2.3   
   12               2.6   

   26               5.1
   28               5.5
   45               6.2
   48               6.6

The longer durations (26 to 48h) were included because there was an interest in seeing what happened to Lag at long fermentation.  The estimates of duration were based on a risky extrapolation using the standard 0.12h-1 end to end Growth Rate: in fact, both the 26 and 28h ones reached x2 volume 2 hours earlier than the extrapolated 28 and 30h (7% error average). 

The 45 and 48h ones reached x2 volume 10 hours earlier that the extrapolated 54 and 58h at 0.12h-1 , highlighting the danger of extrapolating to around 4 times longer than was reliably accurate (18% error average).  The amount of yeast used for the longer times times was around 50 mg: see the later measurement section for accuracy information.  Irrespective, these figures are good enough to provide pointers here.

It appears from this limited data that the Lag duration does not increase convincingly with Total Duration in the time range that was used in the project.  This was unexpected given the reduction in yeast by around 30% between the shortest (7) and longest (12) duration. 

The key point however is that Lag Phase has been measured for the project and is consistent in the range of Fermentation times I use for my dough.

What happens with longer fermentation ?  With the 26 and 28h doughs the yeast amount has been reduced by around a further 30%.  Then the 45 and 48h doughs have another 50% yeast reduction. Lag Phase continues to increase in duration with longer fermentation.

If we know Lag Time we can work out how much of total Dough Fermentation time is exponential growth: real Growth Phase.  Then we can obtain the Growth Rate without Lag Phase.  This is shown in the expanded table below, which also includes the IDY% used:

Total Duration      %IDY   Growth Time   Lag Time    Lag as % of Total Duration

   7         0.094      5.1         1.9            27
   8         0.083      5.5         2.5            28
   9         0.078      6.5         2.5            28
   10         0.07         7.5         2.5            25
   11         0.064      8.7         2.3            21
   12         0.058      9.4         2.6            21

   26         0.025      20.9         5.1            20
   28         0.023      22.5         5.5            20
   45         0.013      38.8         6.2            14
   48         0.012      41.8         6.6            14

The table also introduces the Lag Time as a percentage of Total Duration in the last column.  That column is crucial: it indicates that the Lag Time reduces as a proportion of Total Fermentation time with longer fermentation, even though the hours in Lag Phase increase. 

The immediate finding for me is avoid very short fermentation.  There Lag time appears to be proportionally longer so potential Lag-associated variability is more likely, leading to potential variability in fermentation results.  Once in Growth Phase, the end result is more predictable.

I will not speculate for reduced temperatures, say 17C, as the duration of the period where the dough drops from FDT to 17C is significant (see later post) and the yeast may pause completely during that transition and more.

But how do we know if the Lag Time average of 2.5 hours is realistic for my short fermentations, let alone correct ?  Below we get closer to that assessment, let’s take each individual dough rather than the average.

Previously we had calculated the pizza friendly Growth Rate using:

Growth Rate = 2 / ( IDY% * Temperature * Fermentation Time )

Which gave 0.12h-1 end to end.  Now we can split out the Lag element, as shown in the attached graph, as we have the third Reference point (the orange dot on the graph)

For example taking the above 9h dough experiment to get results for this specific dough:

Growth Rate = 2 / ( 0.078 * 24 * 9 ) = 0.12h-1

But we know the dough was not growing for the first 2.5h (it was in the Lag Phase), so we reduce the growth time to 9h - 2.5 = 6.5h, giving:

Growth Rate = 2 / ( 0.078 * 24 * 6.5 ) = 0.16h-1

Doing the same calculation for all of the doughs, we can add the Growth Rate column to the table:

Total Duration      %IDY   Growth Time   Lag Time      Lag as %    Growth Rate

   7         0.094      5.1         1.9         27         0.17
   8         0.083      5.5         2.5         28         0.18
   9         0.078      6.5         2.5         28         0.16
   10         0.07         7.5         2.5         25         0.16
   11         0.064      8.7         2.3         21         0.15
   12         0.058      9.4         2.6         21         0.15

   26         0.025      20.9         5.1         20         0.16
   28         0.023      22.5         5.5         20         0.16
   45         0.013      38.8         6.2         14         0.19
   48         0.012      41.8         6.6         14         0.19

At first glance, it seems that the effect of reducing yeast upon Growth Rate is minimal, typically achieving 0.16h-1   Again, are these Growth Rates realistic ?  I simply do not know.  Certainly initial gas retention and then gas leakage will cause all of the Growth Rates to be suppressed to some degree.

The 0.17h-1 rate for the 7h dough will have significant potential for timing error as the photographs are at 15m intervals: but I do not use this short time because it is too short for many reasons. 

The 0.19h-1 rate for the 45 and 48h doughs may reflect other factors at play, and I will not comment further on these results other than as follows.  The dough was good, the pizzas were great.  Extremely delicate, chilling them for an hour before use improved the handling.  No noticeable degradation in taste, no change in colour of the cooked dough, no leoparding (as temperature was constant). 

I will not use this extended time in the future as there is no additional benefit to me.

So now the key attached graph: Growth and Lag Times versus IDY%, with power regression curves.  Total Duration is also shown, having an expected Correlation Coefficient of 0.996: almost perfect as the data was derived from the IDY% /  Growth Rate relationship (0.12h-1).

The results:

Growth Time (when the dough is actually growing) = 0.0452 * %IDY-1.044 
With a Correlation Coefficient = 0.989.  This relationship is strong, and would be even tighter with more intervening data around the 15 – 20h range.

Lag Time = 0.389 * IDY%-0.695
With a Correlation Coefficient = 0.949.  Strong again, also could be improved.

So we have dug into the "bucket" of the end to end Growth Rate of 0.12h-1 ….  and have nailed Lag Time and Dough Growth Rate: for my environment, and my dough. 

It is tempting to go back to the original relationship of:
Growth Rate = 2 / (Fermentation Time * Temperature * IDY% )

… and tweak it a bit.   But it won’t make my pizzas any better, and there are other fish to fry.

Pause for a breather.  What else does this third Reference point give us ?

Predicting the end of the Window of Consumption

We have barely covered the “Window of Consumption”.  Can we now predict the end of the Window ? 

All we could say previously was that the Window will reduce with shorter fermentation times.  If we assume the limit of the Window of Consumption is at x2.3 growth (certainly in my case with 62% hydration), we can now use the above results for the 9h dough:

Lag Phase = 2.5h
Growth Phase to x2 = 6.5h
For the End of Window of Consumption:

Growth Rate = 0.16h-1

Fermentation Time for x2.3 = 2.3 / (IDY% * Temperature * Growth Rate )

Fermentation Time for x2.3 = 2.3 / ( 0.078 * 24 * 0.16 ) = 7.6h

Now we get the Duration of Window of Consumption = End – Start = 7.6 – 6.5 = 1.1h

This is pretty short,  so we could start before x2, say x1.8:

Fermentation Time for x1.8 = 1.8 / ( 0.078 * 24 * 0.16 ) = 6h

This gives us an earlier start of the Window of Consumption = 2.5 + 6 = 8.5h, an extra 0.5h

Then an improved Window of Consumption between x1.8 to x 2.3 =  0.5 + 1.1 = 1.6h. 

More manageable.

In summary, the Window of Consumption for the 9h dough is only 1.1h long, and we can extend it to 1.6h: for a 4 dough ball dough “we need to eat” a pizza every 24 minutes.

So we have above a numerical estimation of the Window of Consumption: not really useful: but possible.  A bit like a 72h dough at 24C.

Next I would like to dig the hole bigger in two ways.   Firstly, the next post will look at the data in a different way: as it often helps spot something missed.  First, a pizza.


Casa Farsha Pizza Uno

Base of tomato: the regular base, 70g
Tierno cheese: irregular small clumps, cut into the usual pieces, 50g
Lacon ham: 8pc placed regularly, cut to small size (2cm x 3cm), 25g
Mushrooms: 12 pc placed regularly, thinly sliced fried in butter & celery salt
Artichokes: 8 pc place regularly, cooked, drained & cut into quarters, 30g
Capers: 8 pc place regularly, brine drained, halved / quartered based on size: a tart taste
OR Black olives: 8 pc place regularly, brine drained, pitted and halved: a bitter taste
OR Cooked red pepper strips preserved in sweet brine, 1cm x 3cm, 10 pc spread irregularly all over: a sweet taste
“Valle de San Juan Pallencia” mature sheep & cow cheese: small sprinkle fine chop, 5g
EVOO spiral.
« Last Edit: December 18, 2019, 09:48:52 AM by stef »


Offline stef

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Re: Project Complete…2y
« Reply #25 on: December 21, 2019, 04:58:19 AM »
Part eight of the Pizza Project:

Looking at the Data in a Different Way

Here are some more results obtained from the detailed pizza session data recorded earlier.

The attached graph shows the relationship between Fermentation Times and IDY% over the 4 month period in the Summer of 2019.  To explain the graph: the x-axis (horizontal scale) is hours to achieve x2 fermentation.  The y-axis (vertical scale) is  %IDY used.  The axes are scaled linearly, and the values increase away from the bottom left hand corner. The box showing the key doesn’t really matter yet, we explain it below.

The dots on the graph are my pizza evening results.  Note that the dots are positioned on hourly and half hourly intervals, as I could not confidently measure the Fermentation Time any better than that by eyeballing the dough level in the tubs.

Three regression curve formulae are shown for the lines plotted on the graph.

The uppermost blue curves are from november’s Golden Chalice formula, and the lowermost red curves from the Craig TX table. They are almost perfectly overlaid by power regression curves calculated from the data.

To include the Golden Chalice curves, I re-cast the Golden Chalice formula for IDY (remember it is specified for ADY), by applying a conversion constant (0.75) for ADY to IDY across the 5 to 15h range, then fitting the results to an exponential regression curve giving

 f(x) = 0.8403x-1, with R2 =1.0000, at 24C.   

This is a perfect fit, which is extraordinary: also the power value is exactly -1, which indicates a simpler form of the equation exists not requiring the use of the sine function. 

The re-cast Golden Chalice curve means in practice:

%IDY =  0.8403 * (Fermentation Time)-1

To include the Craig TX curves, I have taken the IDY data points in Craig TX’s tables for 5 to 15h at 23.9C, plotted them and fitted them to an exponential regression curve, which gives f(x) = 0.7631x-1.2729  with a R2 =.997.  This is an extremely good fit, expected as the source data is likely from curve fitting itself.

The Craig TX curve means in practice:

%IDY =  0.7631 * (Fermentation Time)-1.2729

On the graph the middle curve running through the dots is a power regression curve fitted to my data.  The regression curve formula is plotted on the graph.

The power regression curve from my data gives f(x) = 0.86719x-1.0844  with a Correlation Coefficient R2 = 0.941. The  R2 value is high, indicating that the curve is a good fit to the data.

The curve means in practice:

%IDY = 0.86719 * (Fermentation Time)-1.0844

Using the earlier example, if I want to have a pizza evening tomorrow and I have 9.5h available for fermentation: I can start the dough combine at 10am, and have the first pizza dough ball ready to go at 7.30pm.  The percentage of IDY I will need to use is:

%IDY = 0.86719 * (9.5)-1.0844

%IDY = 0.0755     

The previous example in the earlier post using Growth Rate of 0.12 h-1 resulted in %IDY = 0.0731.
The same data, cut a different way.

On the second attached graph, the Growth Rate calculation has been plotted on top of the three curves: the Growth Rate calculation curve is in green.  The overall shape of the three sets of curves is almost identical in this range of Fermentation Times, but they are displaced relative to each other.

In summary at this point, the curve displacement could be due to variation in Growth Rates etc.  discussed above.

Given the graphed consistency, as those who have read so far have expected, let’s extrapolate to the Fermentation Times of around a day and two days.  This is shown on the third attached graph, note the change in the Time scale.

No surprises, the overall curve shapes remain.  Using the longer four doughs described earlier of 26 and 28h, and 45 and 48h I have averaged the yeast amounts (0.024% and 0.0125%) and the Fermentation times (27 and 46.5h).  These are shown as the two isolated data points to the middle and right of the graph.  The data points fall on the regression line.  The regression curve is a better fit for longer fermentations, even though this was also based on the short duration doughs alone. 

My pizzas are made in the early part of the day and eaten in the evening, so for me there are three practical fermentation periods: 1 day (approximately 8 – 12h), 2 day (26 – 36h) and 3 day (50 – 60h)  This project is about short, ie. 1 day fermentation.  I would be surprised if the Growth Rate of 0.12 h-1 would extrapolate accurately into the longer fermentation periods: looks like it doesn’t, but the regression curve does.  In the future I may make more longer doughs, I’m sure the challenges will be different: but will only make one change at a time from my baseline.

However: look at the %IDY involved ….  it's getting very low in the 0.03 – 0.01% range.  Not so much a problem if you are doing a big dough, but being precise at these levels for a small dough becomes interesting ( My routine 4 dough ball fermentations have gone down to 50 mg of IDY: measurement accuracy at these levels is covered later under the weighing scale calibration topic ).

Interestingly the graphs show there is no curve convergence: a bit worrying given that for a Fermentation Time of 29h Golden Chalice suggests an IDY% of just under 0.03, whereas Craig TX gives 0.01%: one is almost three times the other. That is a very big difference, much more than their difference in the 5 – 15h range, which is around two times.  My Growth Rate curve does not converge with either as expected given the earlier discussion.

Where does that leave me ?  I will continue making one day pizzas, logging the results and using:

IDY% = 2 / (Temperature * Fermentation Time * Growth Rate)

or, "if written on the back of a fag packet at 24C":

IDY% = 0.715308 / Fermentation Time

As my ingredients will vary in the future (especially flour blends) I will make slight adjustments possibly, but the above works. 

Now it’s time for the investigation into the huge differences in amounts of yeast which have been reported by differing sources, irrespective of Lag Time and “dough versus yeast”.  What may at least partly explain these huge differences is a variable we tend to forget.  It’s dough ball size (thank you Scott123). 

Or more specifically: total dough mass; then bulk fermentation versus ball fermentation; and the move from bulk to ball.  That’s all at my constant temperature.

The last few posts have been a bit detailed, so here are a few more pizza shots which use lacon and courgette, both matchstick and fine cut.  The addition of sour cream blobs was decisive.  Almost as good as the cheese, jamon serrano and spinach one.

« Last Edit: December 21, 2019, 05:04:09 AM by stef »

Offline TXCraig1

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    • Craig's Neapolitan Garage
Re: Project Complete…2y
« Reply #26 on: December 21, 2019, 10:55:15 AM »
This series of posts was fun to read. Thanks. A couple comments:

The results were more-or-less what I would have expected. I think the vertical shift you see between the curves for my, your, and November's data is largely related to how fully risen/fermented is defined. Where bread is often risen to 2-3X, I think here in this forum, pizza is often risen to 1.7-2X with the average closer to 1.7X.  My model is built entirely on data pulled from this site where yours is entirely built on your 2X rise tests. As such, I'd expect your curve to be shifted higher than mine. It takes more yeast to get to 2.0x vs. 1.7x, AOTBE.

Another observation is that while November had the luxury of working with a fixed yeast quantity (at a given level of hydration), and you had the luxury of working with a fixed temperature, in my model, both are variables, so fitting a model becomes a three dimensional problem. November's growth rate model is defined by a single equation with one variable (temp). Your model is also defined by a single equation with one variable (time). In yours, temp and growth rate are not variables because they are interdependent. As you showed, you can simplify your formula by multiplying them to ge a temperature-specific constant.  My model on the other hand is a set of equations with two independent variables (time and temp) and some other math that I used to deal with the wild variability in the raw data stemming from all the different formulas and workflows that it draws from.  This is why you didn't get a rsq=1 on mine like you did with November's model.

You did it the right way modeling your unique, personal formula/workflow. Your model should be very accurate and repeatable for you. The goal of my model was very different. It's intended to help people find a starting point regardless of their formula and workflow. With mine, some tweaking should be expected.

This model is the most scientifically researched and robust I've seen: https://calbal.altervista.org/ The results I've compared to mine tie pretty closely. I just looked, and it's really close to mine at 75F/24C.
"We make great pizza, with sourdough when we can, baker's yeast when we must, but always great pizza."  
Craig's Neapolitan Garage

Offline stef

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Re: Project Complete…2y
« Reply #27 on: December 21, 2019, 03:53:13 PM »
Hey Craig, you are cheating here as you clearly telepathically know what the next post is... 

so here it is, and sadly more to come...

I will give your much appreciated point of view my full attention tomorrow, as it's getting late in the evening here.  Put another way the vino has been flowing for a while.

The posts were written some time ago, there are a total of 16 posts already written.

I so laughed at your comments on dough fermentation size.  Yes...  Really.


ps this pizza recipe is not "NP" it's something else.


Part nine of the Pizza Project:

Dough Size, Yeast Quantity and that x2

Dough ball size.... does that really affect the amount of yeast that you need to use to make your pizza ?  If it does, why ?

When a dough is created the ingredients interact and generate heat through a catabolic metabolisation reaction.  The dough will lose heat if the ambient (surrounding) temperature is lower than that of the dough.  The RATE at which it can lose heat depends upon its thermal conductivity and the surface area of the dough ball.

Those who make wine or beer at home know that a big ferment (say 50 litres, or 48 quarts) in a bin needs cooling (unless you are in a cold place).  The Fermentation Time is reduced, and the fermentation can become “runaway” unless sufficient cooling is provided.  In contrast a small ferment (say 5 litres) is much less likely to need cooling, more likely warming. 

The contrast is because the ratio of surface area to volume (SA:V) is smaller for the big ferment.  Simple as that.   

Loosely speaking, the big volume in a typical container has a smaller surface area through which it can lose heat, in comparison with the small one's volume.  So the big one cannot lose heat as fast.

Taking a dough ball, surface area and volume may vary: a big dough ball has a smaller SA:V than a small ball.

If there are thermodynamics gurus on the forum, I’d appreciate their comments on the words below.

During fermentation the rate at which a dough ball can release heat else it warms up from its start temperature (or the opposite), is primarily controlled by two things:

Firstly the convective Heat Transfer process and Coefficient: these are independent of dough ball size, and will reduce as the gas volume of the dough increases and it becomes a better insulator. 

Secondly, the SA:V of the dough ball.  SA:V varies massively by both dough shape and size.  A large dough, assuming a spherical shape (for calculation convenience), has a low SA:V whilst a small dough has a high SA:V. 

For example with commercial artisanal pizza making, a bulk dough ball 60cm in diameter (approximately 125 kg of dough, 280 lbs) would have a SA:V of 0.1.  With large domestic pizza making, a bulk dough 15cm in diameter (approximately 1.9 kg, 4.23 lbs) would have a SA:V of 0.4.  With a dough ball 7cm in diameter (approximately 200g, 0.45 lbs)  the SA:V is 0.86. 

The higher the SA:V, the faster the dough ball temperature adjusts to ambient temperature.

The lower the SA:V, the more the ball retains heat: and could increase in temperature due to the reaction.  This point is certainly the case with loaf sized dough in a bread factory: maybe 700 – 800g dough (1.3 – 1.7lb).

Commercial pizza making uses biggish bulk fermentation (think Neapolitan videos) under a damp cloth on a work bench or in a lidded tub with a stillish air space above the dough.  Then the balls are made and carry on fermenting in trays with still air above the balls.  For other types of pizza the balls may be made straight from the mix and refrigerated.

Domestic pizza making does small scale bulk fermentation under a damp cloth or in a lidded tub, then the balls are made and carry on fermenting, or no bulk fermentation, just straight from mix to ball.

Thinking through the above, a starting hypothesis could be that a small dough ball could lose heat almost as fast as it is generated by the metabolic reaction.  However the dough is surrounded by still air which is about as good an insulator as Styrofoam.  Air is also an extremely poor medium to absorb (hold) significant amounts of heat:  many of us use closed containers with lids: still air.

To calculate the rate of dough heat loss accurately the Fourier Law needs to be used with some increasingly unpleasant Calculus given the ball changes shape, size, density and chemical composition during fermentation: difficult to usefully do.

However…. we can simply work out how big the dough ball size effect is.  If you are a dedicated pizza enthusiast, see the attached table “Amount of heat needed to be lost per hour to remain at constant temperature”. 

In the table dough weights of between 200g and 160kg are used to estimate the difference in the amount of heat each dough has to lose to maintain its internal start temperature, which we take as the mix Final Dough Temperature (FDT).

The rate of heat generation caused by the dough fermenting is estimated for spherical dough balls and one “rectangular” dough of 160kg which is around 30cm x 10cm x 49 cm in size. (approximating a bench bulk dough fermentation as seen in some NP videos).   The rate of heat generation per hour used is a guess: 0.1 calories / gram / hour (in the blue cell of the table).  This rate does not affect the end result.  The numbers in the yellow and amber boxes are RATIOS: they are not affected by the guessed rate of heat generation. 

The tabulated yellow box number is the ratio of the amount of heat lost for a 200g ball to the amount lost by a 1.5kg bulk dough.  The ratio is 2: so to stay at a dough start temperature, the bulk dough has to lose heat twice as fast per square centimeter of surface area as the dough ball. 

(Assuming the dough is warmer than ambient temperature, if it’s cooler the heat flow reverses into the dough to warm it: no problemo).

The tabulated amber box number is the ratio of the amount of heat lost for a 200g ball to the amount lost by a 160kg bulk dough (the “rectangular” shape)  That ratio is almost 28.  That is a big difference to 2: compared with the dough ball, the bulk dough is going to be at a significantly different temperature. 

I can’t say how much the dough heats up not having macroscopic figures for the heat released by fermentation  (other than an anecdotal 18-20% increase during a commercial bread loaf fermentation).  It is also certain the heating rate varies with time throughout the fermentation, especially comparing the Lag Phase to the Growth Phase and the onset of maltose consumption.  Further, in Growth Phase the creation of CO2 changes the Heat Transfer process (generalising: elastoplastic medium transformation into a foam) and Heat Transfer Coefficient, reducing the dough thermal conductivity making it even more difficult to release heat. 

I suggest that the differences we see in the amount of yeast reported as used to obtain specific Fermentation Times are partly due to the fact that a relatively big ball of dough heats up more than a small one. 

As the big dough heats up the Fermentation Rate increases, so the Fermentation Time is reduced compared to the small ball.  So you use less yeast to compensate for the elevated temperature. 

Put another way, the declared fermentation temperatures used by others often underestimate the actual dough fermentation temperatures, with the Growth Rates being higher, and the yeast amount being reduced to compensate for this (note a fermentation container air temperature measurement is NOT the same as a dough temperature measurement, ie within the dough itself).

As a very relevant aside (I do apologise for bringing b**** into a pizza discussion), when making my 5kg bulk bread dough it is at an FDT of 25C (77F) when placed in the refrigerator: it takes up to 9h to drop the core temperature to 11C (52F).  This is with active refrigeration (heat REMOVAL via the refrigeration unit and with an internal fan, unlike heat DISPLACEMENT with a passive cool box and ice blocks). 

With a recent bread dough, I tried to measure what happens.  Please bear with the journey, there is an end message.  On the attached diagram the left hand "box" represents the rectangular fermenting dough tub after cooling in the refrigerator to 17C (63F) by 5h, and the right hand box after later warming up.  The blue dots are measurement points with temperatures shown.  The refrigerator temperature is set to 11C (yes, 11C).  Key observations are:

The dough started at the FDT of 25C throughout the entire mass: 5h later in the refrigerator there was a higher core temperature (note the dough edges measured were actually 5cm from the real edge).  So we see more heat loss at the edges, as expected.  The cooler end of the box had more free air movement space outside, the other was closer to the refrigerator wall.

In reducing the average temperature to approximately 17C (63F), the cooling rate overall was 1.6C/h.

So for 5 hours the dough is at a temperature higher than that used in my bread Fermentation Time calculation (based on 17C): on average the dough is 4C (7F) higher.  That makes a significant reduction to the predicted Fermentation Time. 

Therefore if we look at a planned 10h bulk fermentation at 17C it really is 5h at 21C (70F) and 5h at 17C, given a FDT of 25C.  That reduces the expected Fermentation Time by 1h to 9h: 11%, with active refrigeration. 

In the case of a passive cooling environment, the planned 17C fermentation temperature may not be achieved in the centre of the dough AT ALL.  For a 24h fermentation, it could even be really 12h at 21C and 12h at 17C.  Then the Lag Phase will to an unknown degree offset this, or perhaps not.

The right hand box shows the dough at the end of bulk fermentation (much later) when it has warmed for 2h 45m:  the heat distribution is more even, I have included this to show the heating rate overall of 1.5C/h under outdoor conditions at 26C in the shade with a wind: good air circulation.

The rates of heat loss and gain were measured at 15m intervals during the cooling and warming periods: the rates were uniform.

Finally let's revisit a sentence above: "The cooler end of the box had more free air movement space, the other was closer to the refrigerator wall."  So air circulation differences have measurably affected the rate of dough temperature reduction.  The refrigerator has air chilling being maintained and the temperature of that air held through active energy removal (refrigeration unit), and fanned air circulation. 

This is a massively more aggressive cooling environment than a passive cool box or cool room, where air temperature may also vary due to a lack of circulation.  So instead of the example above showing an 11% reduction in fermentation time, that will be a conservative estimate.

Yes, I have strayed from my 24C focus to make this point !

To summarise, to get the same end result:

Less yeast is used in a commercial passive situation as compared to a passive domestic bulk and ball. 

More yeast is used in a passive domestic mix straight to ball situation.   

Even more yeast is used in an active domestic mix straight to ball situation. 

The bigger the mix, the lower the yeast amount predicated by the elevated core temperatures. 

The more aggressive the temperature control regime, the more the yeast amount reflects the target temperature. 

Going straight to ball after mixing minimises some of above variability, especially if the FDT is the same as the fermentation temperature. 

A very important point is that fermenting dough temperature measurements are often measuring the air in a box, not in the dough itself.  This is why I always locate temperature probes between stacked tubs in direct contact with the tubs during fermentation (see later post on measurement).  This is a compromise also as the probe wire will tend to equilibrate with the air temperature, which is also the case if the probe is located within the dough ball itself.

So where does this leave the yeast quantity discussion from earlier ?   If the actual pizza dough temperature is being underestimated, the actual dough Growth Rates will be higher than expected.  It follows that estimation constants used by most of us to predict the yeast amount needed for the pizza dough ball are in error.

For instance, going back to the 0.056% IDY from earlier examples and assuming an 8h Fermentation time as in the Craig TX table:

If we assume for example that the dough is actually at 25C due to the metabolic reaction and dough size, not 24C (25C equates to a conservative half of the reported 19% increase in dough temperature averaged across the fermentation, calculated as 24C + (0.19 * 24) / 2 ) then the Growth Rate would be approximately 0.17h-1  (Rate change of 6.5% / C used, 10% / C gives 0.18h-1 ).  This allows us to work backwards using:

Fermentation Time = 2 / ( IDY% * Temperature * Growth Rate )

Fermentation Time = 2 / (.056 * 25 * 0.17) = 8.4h

This Fermentation Time would give a negative Lag Time of 8 – 8.4 = - 0.4h, which is nonsense. 

So whilst dough temperature has made some difference in this example, it’s not enough.  Larger volume doughs with a bulk fermentation period would further increase temperature, but if the bulk is for the first half, ie 4h of an 8h dough, the first 2.3h of that period is in Lag Phase.  This does not leave much remaining time for the dough to grow quickly before the bulk is broken down into balls.  With a big dough at longer times this would not be so. 

So whilst the discussion of bulk versus ball and SA/V is valuable, it’s only part of the difference in yeast amounts reported.

What other options are there to explain the difference ?  There are two. 

First, the CY / ADY / IDY yeast conversion factors.  Clearly there is some variability, but I cannot add usefully here, other than when you make a conversion the ratio used can massively affect the results: I am aware of conversion factors from ADY to IDY ranging between 0.8 and 0.66 for instance. 

If we work through an example using the Golden Chalice formula reworked for IDY, if we change the conversion ratio ADY to IDY from 0.75 to 0.66 (both commonly used conversions: see SFBI note on Fresh Yeast vs Instant Yeast, also theartisan.net Yeast Conversion Table) this results in the Golden Chalice model fitting my data (see attached graph).  This is perhaps a bit extreme, but within the ranges discussed by the SFBI. 

I estimate Craig TX is using around 0.75 in his table, SFBI suggest 0.8 would be an alternative.  But still not making that big a difference.  I also noted that November’s posts show individual dough balls fermenting in his chiller, maybe that is why his results are closer to mine: no bulk fermentation ?

The second option to explore is “x2 growth”.  The point at which the dough has grown to double its original size. 

Is this what others are actually working to, or is it an assumption, or do experts simply know when a dough is ripe enough to start using, or as Pete-zza says, is it just an untested legacy from bread making ?  Here we are back to the old VARIABILITY discussion of the early posts. 

My x2 may not be what others actually use.  In retrospect, I should have nailed this earlier.  All those tub bubble shots: a case of art subverting science ?

In a commercial environment I would expect dough balls to be used as early possible to maximise the Window.  This is also attractive with the more robust dough condition, given the pressures at work to perform quickly and consistently.  So how EARLY can the start of the Window of Consumption be ?  Let’s say x1.7, not x2.  I know as low as x1.6 does work with my dough: not the airiest, but dead easy to form a disk without holing it and it’s not too elastic.  Some of the NP videos online look like doughs at well under x2 (let’s keep hydration out of this for the moment). 

So let’s work the numbers backwards for an 8 hour fermentation, at 25C, and assume that the Growth Rate and Lag Time at 25C is almost the same as at 24C, using:

Growth Rate = 1.7 / ( Temperature * Fermentation Time * IDY% ) and

Fermentation Time = 1.7 / ( IDY% * Temperature * Growth Rate )

Using a Lag Time of 2.3h, Growth Time of 5.7h ( 8 – 2.3 ) and and a dough temperature of 25C:

Growth Rate = 1.7 / ( 0.056 * 25 * 5.7 ) = 0.21  (this is a very high dough rate, close to yeast)

So bringing in Lag Time to get a total Fermentation Time:

Fermentation Time = 1.7 / ( 0.056 * 25 * 0.21 ) = 5.8h plus Lag Time of 2.3h = 8.1h.

Hmmm…. Has this nailed the 8h dough question ?  Close enough,

As of September 2019 I stopped using a 30m resting period after mixing, going straight to ball after mix.  However, I have now stopped making comparisons with other workers fermentation results.   

It's overdue for a recipe, using 200g dough balls.  This one is saved up for serving last in the evening, and it stops all conversation.  Totally.  This is the favourite of all of our guests.  Certainly it has a deceptive appearance.

It uses loganiza sausage, a traditional Spanish type, nothing unusual except it has a higher pork content than many sausages.  A bit like a French chipolata in shape but without herbs.


Desayuno Pizza

A big overload pizza, with moderate cornicione

Dough base ellipsoid shape for 2 eggs (medium size), or circular base for 1 egg
Base of tomato: the regular base, 70g
Tierno cheese: irregular small clumps, cut into pieces totalling 30g, ensure a centre “well” is created on the pizza for egg/s which is covered with cheese
Emmental cheese: irregular small clumps, cut into pieces totalling around 10g.
Smoked bacon: placed in ring close to centre leaving a central “well” for egg /s, 5 slices chopped, fat removed, fried, remove grease after cooking, 100g pre cooked weight,  must be smoked.  Regular US bacon is best not cooked too crisp.
Mushrooms: 20 pc placed in ring outside bacon, thinly sliced lightly fried in butter & celery salt, 100g pre cooked weight
Loganiza sausage: in next ring adjacent to cornicione, 3 of, fried slowly to high char colour, remove grease after cooking, diagonal thin slices, 100g pre cooked weight
Eggs previously removed from shells into bowls  1 / 2 pc
Partially cook pizza in low heat area of oven for approx 30s, remove from oven
Immediately pour raw eggs into central pizza well /s and return pizza to oven to complete, cook to point of thin skin over eggs only
Fresh black pepper sprinkle on eggs after cooking.

Offline stef

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Re: Project Complete…2y
« Reply #28 on: December 21, 2019, 04:04:31 PM »
Ah well the extra vino helped this one out of the door.....

Part ten of the Pizza Project:

Fermentation Temperature Control

Accurate and reliable temperature control is important for me to “manage out” variation so my pizzas become more predictable.  Attached is a poor picture of the cool box setup used up to mid October 2019 for all of the doughs discussed here.  The Thermapen is cosmetic.  Below we cover how the cool box has become a fermenter accurate to +/- 0.3C over 48h periods.  The reason I don’t have more pictures is because since then the box was cannibalised for a much better replacement system. 

The rig is a domestic cool box with a “Peltier effect” solid state refrigeration unit built into the cool box lid, using fan forced air circulating within the box, powered at 12v DC for use with a car / auto battery.  There is no temperature control built in.  The box refrigeration unit is connected to mains AC via an external power supply.  The refrigerator and fan are temperature controlled by an external “Inkbird” brand ITC-308 electronic controller.

Inside the box is a heater: a 25w waterproof aquarium heater immersed in a one litre glass bottle of water.  Its integral temperature controller is not used, it is again switched by the external Inkbird controller.  The heater has a maximum temperature of 33C.  The water provides thermal mass and increases the surface contact area of the heater to that of the bottle, to avoid hotspots and improve heat transfer to the air.

The temperature is maintained to +/- 0.3C by the Inkbird controller using the temperature sensor which is hard wired to the Inkbird, and placed inside the box.  The sensor had previously been calibrated at + 0.2C for the doughs covered in the “closing in” pizza sessions earlier in this thread.  The adjustment was based on Thermapen thermometer measurements of dough balls immediately after they were removed from the box, ready to use.  That adjustment was made when ambient temperature was around 30C. 

The Inkbird sensor is extremely accurate, but actual dough ball temperatures were consistently down at 23.8 when the controller was set to 24C: this must reflect temperature sensor placement within the cool box.  We are interested in dough temperature, not air.  (note comments in last post on measuring the temperature of the dough itself).  Temperature calibrations and accuracy are covered in a later post.

Occasionally there is a little overshoot and undershoot (o/u shoot) after either the refrigerator or heater switch off, this is within +/- 0.2C and lasts for 5-15m.  In the Summer I run the temperature setpoint at 23.9C.  In Spring and Autumn the setpoint is at 24C, and 24.1C in Winter.  This is to minimise o/u shoot duration given the seasonal change in ambient temperature.  I know when I have o/u shoot as I have set the high and low temperature alarms just above and below the +/- 0.3C threshold. (nominally 24.4 and 23.6C in Spring and Autumn).  The box is heated / cooled to target temperature of 24C at least 24h before use to allow the temperature to equilibrate.

The refrigerator and heater only switch in briefly to compensate for heating / chilling o/u shoot respectively.  The cool box will sit for 2-3 hours without going outside the +/- .3C threshold, longer when the ambient is close to 24C.

To get this level of accuracy was surprisingly straightforward, but time consuming during temperature calibrations (later) and dry runs with pizza sessions to tune the numbers.  As pizza sessions were usually weekly, it took around 6 weeks to get it right initially, and then checks on every ball during the "closing in" led to the calibration adjustment.  I still check every ball before use, occasionally I miss one with the vino.

Usually within the cool box we use a vertical stack of 4 loosely lidded dough ball tubs, either 500 or 550ml volume.  In summer when entertaining guests, we can run two stacks giving 8 tubs, but this requires removal of the heater to make space.  This is not a problem as the guests don't notice with the vino (more u/shoot after the refrigerator has been switched off by the controller, potentially increasing Fermentation Time by a few “unmeasurable minutes”).  When we need more than 8 tubs sadly I have to admit to "winging it".  Bottles have been emptied by then though.

The temperature variation from top to bottom across the stack of 4 dough tubs is up to +0.7C when running at 24C.  Three thermocouple probes are located between the tubs, with the Inkbird probe in the middle: this probe is bonded to an aluminum plate to provide a larger measurement surface area directly in contact with the base of the tub above, and to some degree with the tub lid below.  The thermocouples are NOT in free air.

( I have a set of experiments in work on temperature environment around a range of tubs and the impact of forced air flow and water bath immersion with the replacement system.  All I will say here is that with short fermentations and / or potentially rapid changes in temperature such as with dough cooling and warming, “still air” temperature measurement is misleading). 

Over the Summer months at around 30C ambient, the cool box is capable of cooling at around 1.6C / h.  In the Winter / Spring months at around 18 - 20C ambient when the cool box is primarily being heated, it is capable of heating at around 0.2C / h.  This is with a load of 4 dough balls.  An asymmetric situation giving a saw tooth temperature profile.

I do not look at the state of the dough ball rise until just before the oven is likely to need firing up, 1.5h before the end of Fermentation Time.  In the past I used to look frequently in the last 3 hours, until more confident.  As the ambient is up to 6C warmer in Summer than 24C, and down to 7C cooler in Winter I don’t want to leave the cool box open for any length of time.  (See the attached chart of actual ambient temperatures recorded at dough mix time for 55 pizza sessions, also the weather service chart of regional monthly temperatures:  Temperature is on the vertical axes of the charts). 

When the dough balls are removed from the cool box to form the pizza disc their temperature is measured using the Thermopen, pushing the probe around 1cm into the ball.  The measuring thermocouple is in the end of the probe.  The balls are always between 23.8 and 24.3C with real pizza sessions.  Then the pizza discs are immediately formed with no warming up period needed, hence no additional CO2 release and bubbles leading to leoparding.

For its cost, the Inkbird is amazing:  you can get it for multiple voltages, form factor and electrical plug type, and it has lag settings allowing you to use a compressor based refrigerator for cooling with up to 2Kw switching spikes, or 2Kw continuous load. 

Temperature Control at the start of the pizza making process

What about temperature at the start of the process, when it's just ingredients and mixer ?  The start has to be at the right temperature: a mixed Final Dough Temperature (FDT) of 24C.  FDT has caused me some embarrassing errors.

Before getting to the detail, how important is it to exactly hit the planned 24C FDT ?  Does this impact Fermentation Time ?

An example: say we unfortunately end up with an FDT of 26C, and the next week another mix FDT of 22C:  how long will it take for the balled doughs to get to the planned 24C once they are in the cool box ? 

Earlier we measured the rate at which the cool box can cool and heat dough balls, how many degrees C per hour.  This allows the estimation of the time from creation of dough balls straight after the mix finishes, to the point at which they reach 24C in the cool box. 

The example warm 26C dough can be cooled at 1.6C  / h, so it will take 1.25h to drop to 24C:  pretty quick, and the effect will be to reduce a planned Fermentation Time of say 10h, by 3 minutes assuming a linear dough heat dissipation:  overall, not an issue to the pizza.

The example cool 22C dough can only be heated at 0.2C / h, so it will take 8.7h in the box to rise to 24C.  A very slow increase, the effect will be to increase a planned Fermentation Time of 10h by 22m assuming a linear dough heat dissipation: significant.  So get the FDT right.

In addition there is the potential variability introduced by the Lag Phase.  Any ongoing temperature change during the Lag period will increase its duration, whether temperature changes up or down.  So get the FDT right.

( Aside: since project completion the replacement system can achieve much faster rates of heating per hour (1.5C / h), and in the event of a power outage the temperature will drop or increase at up to only 1C / 5.5h with an outside / inside temperature difference of +/- 10C.  Dough results are consistently different but comparable ).

Cue for a recipe.  This one is deceptively simple where the difference between getting it right or not is substantial.  Our biggest challenge was getting the white onion balance right: air dried to remove a lot of the moisture but not as fiercely dried as if par cooked.  The second challenge was avoiding fatty cheeses else it becomes super greasy (cheddar is not for us, I know some like it but not on a pizza !)


Queso y Cebolla Pizza

Base of tomato: 85g: more than the regular base
Air dried raw white onion: 150g fine chop, dried in sun for 5h @ 30C equivalent "under a bug screen"
Emmental: circle in centre 1/3 of cheese cut, 30g
Tierno: ring around Emmental 1/3 of cheese cut, 35g
“Montesino Queso de Cabra” semi mature goat cheese: outer ring 1/6 of cheese fine cut, 10g
“Oveja Viejo” sheep cheese, v mature: outer ring also, 1/6 of cheese, fine chop
OPTION: Jamon Serrano: regular spread, 15 pcs,  fat removed, cut to medium pieces 2cm x2cm, and “crunched up”, 20g
OPTION: 6 pc capers regular positions
EVOO spiral (leave off if fatty cheese mix).

Offline TXCraig1

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Re: Project Complete…2y
« Reply #29 on: December 21, 2019, 08:19:07 PM »
To your question above on thermodynamics, a lot of heat in the dough is lost via IR. The bigger the dT to the surroundings, the more heat lost via IR.
"We make great pizza, with sourdough when we can, baker's yeast when we must, but always great pizza."  
Craig's Neapolitan Garage


Offline stef

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Re: Project Complete…2y
« Reply #30 on: December 23, 2019, 05:16:12 AM »
Thanks Craig, appreciate the thoughts.

On your earlier comments, again thank you for your insight.

Yes, it could take more yeast to get to x2 rather than x1.7.  However, the curves are also horizontally shifted: I had a hunch that the “combined offset” or whatever, is due to an unmeasured temperature difference: my post after yours alludes to that.  Also the yeast conversion factor bit: there is more on that in a later post as since writing the original words other stuff has happened.

I really did laugh when I saw your words on x1.7.  And the air got a bit blue.  I had homed in on x1.7 by playing around with different numbers, and that ratio was the best fit for my data (including stuff not in my posts).   But x2 is a bit more “sporty” to use.

Yes, working with too many variables is a monster headache.  It’s why I used the bucket.  I think the problem, if looked at in 2020, is multivariate and possibly combinatorial.   Your endeavour trying to deal with the “wild variability” is much better understood by me now, and I appreciate much more what occasional frustration it may have caused.

I looked at CalBal: I think we have got further than that, but clearly it is valuable given the endless posts on this site from enthusiasts struggling in the early days of their journey.  To which you and a handful of others have dedicated what must be a huge number of hours, which must have been in part a challenging commitment.  It certainly can take over a large part of your life.  I’m having great fun with the experience: I have not had to play a game of Sudoku to keep my old brain alive for well over a year.

On the thermodynamic front, thanks again.  In the context of SA / V Boltzman’s Law is a surface area law too.
For a pizza launched into the oven, the effect must be huge. 

With a pizza dough being fermented and gaining / losing heat, it’s not going to make much difference as 25C to 17C is only a dT of 8oK, and the plastic containers (mine are polypropylene) block a significant amount of IR. 

Jumping ahead, most of my current experimental doughs are in a temperature controlled waterbath to take advantage of the massive water SHC, and the water will more or less completely attenuate any IR transmission: the doughs are similar to ones in air, but not the same.

Putting my mind back thirty years or so, I do not remember anybody doing heat exchanger design (liquid to liquid and gas / steam) invoking IR losses or gains: at extreme temperatures this may not be so, also with low liquid / gas flow rates.  Likewise semiconductor heat sink design is all about surface area conduction and air turbulence, with no account of IR other than painting them black...

Separately I have been playing with a forced air system, this is having dramatic effects upon dough heating and cooling rates, but in comparison with water, not much good.

I do think trying to cool a bulk dough efficiently is a big elephant in the room.


Offline stef

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Re: Project Complete…2y
« Reply #31 on: December 27, 2019, 12:30:34 PM »
Part eleven of the Pizza Project:

Preparing Dough: from ingredients to placing in the cool box.

The baseline dough preparation process I have used is given below:

Open the Log Book.  Something not mentioned to date: I am on the 7th Log Book of the project.  Everything gets written down, so when the after-the-event reviews are made we have a chance of establishing cause and effect, what we like and points to carry over into the next session etc.  During the writing of these posts the Logs have been essential.  They also include “great” and utterly atrocious ideas, “workings out” and any literature notes.  Building a picture.  Many scribbles and records. 

The preparation process starts the day before eating: review the last pizza session and any intervening notes.  Then prepare for the pizzas tomorrow, including running spreadsheet calculations to hit FDT and yeast for fermentation duration, and the time when the yeast is to be put in to meet the x2 target.  There are a lot of spreadsheets, but these days it’s just the FDT and yeast sheets that are used, and rarely the flour blend calculation.

The approximate temperature of the stored ingredients is known so I run the FDT calculation then adjust the ingredient temperatures to fit.  Often this leads to chilling the water and sometimes the flours: they then have overnight to equilibrate to the temperature needed: not just the flour temperature at the top of the bag, and the water at the top of the bottle.  I am always working back from where I will be, at FDT.   

All temperature measurements are made in the process using the Thermapen, sampling flours and dough at several different points and making sure the water is shaken in the bottle first.

To chill the ingredients they are put into in the external wine chiller when it’s Autumn and Spring (it is reasonably accurate between 12C and 17C), and in the Summer they go into the outside or inside refrigerator (outside one is set cooler and doesn’t get opened as much).  I avoid chilling flours to less than 15C: explained later.

We rarely need to warm up ingredients: if so, they are moved into the central part of the house to do this: usually flours placed in the room with the log stove.

I have done this “day before preparation” so many times, including for bread making, that my ingredient temperatures are routinely close to what is needed.  If it is an issue, I will always settle for a slightly higher rather than lower FDT, as it has less effect upon my Fermentation Time (see cooling and heating rates per hour in earlier post).  It is just part of an extended “mise en place” activity.

The next morning, it’s dough time.  All ingredients weighed separately in containers, no multiple ingredient tareing: too much hassle if you make a mistake.  No hand mixing.  It’s not just that I don’t have the strength for the mixing, it’s that mixing is potentially a variable, so we try to eliminate it completely: absolutely rigorous process and timing.  If the dough is a bit sticky or dry, so be it.  The mix stays the same.  Record it and see if there is a knock on downstream irregularity.  Even so, two “identical’ mix batches within an hour of each other often come out of the mixer different: particularly stickiness.  When I used to do 30m bulk stand after mix, they were by then inseparable in feel.

We used to have a Kenwood Chef orbital mixer, the approximate equivalent of an old Kitchenmaid, this was more heavily built with metal not “less than metal” parts.  No discussion here relates to that mixer, except for the learning experience particularly with those “toy J dough hooks”.

In came the replacement Kenwood Major, to allow the use of the separately sold "spiral dough hook thing".  The hook is 660g (1.5 lb) of stainless steel and comes with a manufacturer warning, do not use with small machines and do not use with more than 1kg of serious dough.  But of course, it is still a domestic mixer.

Overnight my world of mixing changed.  I have not dared to use it with more than 1kg of pizza dough.  At 1kg of dough the mixer head bounces up and down, it makes “grinding to a halt” type noises, the bayonet of the dough hook and the rotating orbital part of the mixer get warm.  What gets warmer however is the business end of the hook, but the central part of the hook remains cool.  Remember that for later.

Pictures of hook attached.  Now we know what a mixed dough can be.  Nearly all of the mixes referred to here used this hook.  It does not like ice lumps, they catch in the small gap between the bottom of the hook and the bowl. 

The mixes made without the hook been big doughs for lots of pizzas when entertaining guests: up to 2kg a go, they have been made in my bread mixer.  I am not confident that the differently mixed pizzas can be told apart, the mixing steps used are the same, the mechanics of mixing are different, the FDT’s were slightly higher (a different FDT calculation is used now with the bread mixer, a Germany-only version of the Bosch universal plus).  As an aside, I can do 1.6kg of 68% hydration bread dough (50% spelt wholemeal, 50% strong white) in the Kenwood with no problem.

Many different ingredient combinations and mixing techniques have been tried here in the past, most of them have worked: I don’t know if they have worked consistently well.  However the ambition is simplification and repeatability: not aesthetically satisfying state of the art dough technique.  So below is what is done at dough time.

The FDT calculation is run again using the actual ingredient temperatures in the morning.  Sometimes the water is adjusted using the thermodynamic mixing model described later.

Once “mise en place” the salt is added to the water in the mixer bowl.  The bowl is swirled around by hand to dissolve the salt. Then all of the flour is added (not pre-sieved, maybe that will change one day), the IDY is sprinkled on the top, the bowl placed in the mixer and mixed on the lowest speed for 10m.  I am aiming for some gluten development with the mixer and full distribution of the small amount of yeast needed given the small batch sizes (typically 0.24 – 0.44g of yeast, a few as low as 0.05g).  I got giddy trying to measure the hook RPM and gave up on that.

After the 10m mix the dough temperature is immediately measured (FDT) whilst it is still in the mixer bowl, the temperature hardly varies across the mixed dough.  The dough is removed onto the granite surface (it comes out cleanly with nothing left in the bowl after a few scrapes).  No matter what I do, sometimes the dough comes out looking slightly different.  At this point I may have to work fast if the granito surface is warm (30C) or very cold (15C).

The balls are immediately formed, scaling using a plastic dough cutter and flipping the balls onto my left weaker hand in succession, back and forth to identify weight differences and fix them.  They are then placed in polypropylene tubs which have been lightly coated with spray can Extra Virgin Olive Oil (EVOO), the lids are fitted loosely and the tubs are then stacked in the cool box.   When my spray can runs out I am not sure if I will replace it as using regular EVOO with my finger works fine, and I’m beginning to think that the spray EVOO dough balls are greasier when tipped out to form a disk.

Going as quickly as possible, it takes around 4 - 5 minutes between switching the mixer off and the 4 dough balls being in the cool box: longer if more balls (10m for 10 balls).  Polypropylene tubs allow the release of dough balls at pizza time far more easily than glass tubs for me, no idea why other than polypropylene containers get coated with a release chemical during manufacture.  (with long fermentations the glass tubs work better at 24C)  Bread bags have not been good with my process delivering a very sticky dough and needing a huge amount of bench flour.

Balling directly from the mixer, the dough is stickier than if it has been left to rest (I used to rest for 30m in a tub in the cool box after mixing before forming the balls).  As they are in tubs the “perfection” of the ball shape, base pinching etc. does not appear to matter in our experience: the tubs have almost vertical sides, so there is limited lateral spread of the dough.

The cool box has been switched on previously and the empty tubs placed in to get everything to target 24C (75C).  The cool box may have also been used overnight to heat up water for the next day mix.

Now the important element....  Dough Temperature.  When I need to be accurate with mix temperatures to get a 24C FDT for handover to the chiller.

Before that it's time for some early project pictures: Six big builders installing our oven (horno) in the new outside kitchen (cocina), and the finished horno installation.  Then the first pizza (yes, everybody starts somewhere...)  ….  And what happened next, as a segui to the next post.

« Last Edit: December 27, 2019, 01:36:42 PM by stef »

Offline TXCraig1

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Re: Project Complete…2y
« Reply #32 on: December 27, 2019, 12:47:57 PM »
Whereabouts in the world are you located?
"We make great pizza, with sourdough when we can, baker's yeast when we must, but always great pizza."  
Craig's Neapolitan Garage

Offline stef

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Re: Project Complete…2y
« Reply #33 on: December 27, 2019, 01:40:20 PM »
South East Spain, on the Mediterranean Sea  ;)

Offline stef

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Re: Project Complete…2y
« Reply #34 on: December 29, 2019, 10:41:13 AM »
Part twelve of the Pizza Project:

Achieving the 24C FDT

This is how the 24C FTD is achieved using a mix of basic thermodynamic and Dough Rheology calculations.

I have come across the empirical Predicted Dough Temperature (PDT) and “Friction Factor” formula approach on this forum, also in different baking forums.  As a former geek, I find this unsatisfactory: but it is clearly better than guesswork.  Here is how to calculate a process-oriented and more accurate temperature.  Sorry readers, some more science stuff.

To calculate the temperature of a dough ingredient mixture (assumed not to be reacting) a simple thermodynamic mixing technique is used.  You measure the temperature and weight of the individual dough ingredients to be mixed (such as 300g water at 15C, 500g of flour at 23C) and look up their Specific Heat Capacities (SHC’s). 

SHC’s are thermodynamic constants.  You can then calculate the final temperature of the mixture.  SHC's are given here in SI units: they look weird but SI is easy to work with in this case: look at engineeringtoolbox.com for US friendly units.

The SHC of lightly mineralised water is around 4.19  kJ / kgoC and white flour around 1.59 kJ / kgoC.  The SHC of water is extraordinarily high, and this helps us a lot.  We calculate the final mixed temperature (called “TTemp” below) as:

TTemp = ((water g * water SHC * water C) + (flour g * flour SHC * flour C)) / ((water g * water SHC) +( flour g * flour SHC))

Where water g and water C are weight and temperature of water respectively, flour g and flour C are weight and temperature of flour respectively.  The calculation is given with brackets so it can be cut and paste-ish into a spreadsheet.

An example to make this real:

If we have 300g of water at 15C, and 500g of flour at 23C, the final temperature of them mixed together should be:

TTemp = ((300 * 4.19 *15) + (500 * 1.59 * 23)) / ((300 * 4.19) + (500 * 1.59))

TTemp = 18.1C   …. the predicted final temperature of the mixture.

Aha you may say, that’s how to to work out my PDT !  Not quite.  This approach is for a mixture which is not reacting, a non reactive mixture:  but as we mix our dough, there are complex chemical reactions taking place, meaning the chemical and physical state of the dough is changing as it comes together.  This provides the extra part of the dough temperature change: the reactive mixing process itself:  enter the subject of Dough Rheology, the changing dough flow and shear processes occurring in the dough as it reacts.  We will call this extra part the Rheology factor. 

The temperature calculated above (“TTemp”) is usually the main component of dough temperature change. No matter what you do, this is unavoidable.

(An aside comment: as the prediction concerns just the first 10m of the life of the dough, it is unclear to me if there is any heat released by the Lag Phase of fermentation which starts during the mixing, or if that energy is used purely to mobilise Lag reactions.  Note the addition of salt to water before the mix does not lower the water temperature.  That effect only takes place when the salty water is around freezing point. )

Now the extra part, the Rheology factor: a bit for the enthusiasts.  Again we can go to the Netherlands for some answers: the initial research of Arie Bloksma and his collaborators: they spent their careers looking at the Rheology of dough.  It is complex, and whilst many individual rheology processes are understood under specific conditions, in combination things get tricky.  As a warning of how challenging this is, look at the Computational Fluid Dynamics (CFD) mixing simulations of a simple dough mix used by Luchian et al (2013), Figures 3 to 6. Figures 5 and 6 are the “stuff of nightmares”. 

I have two simpler ways of estimating the Rheology factor of mixing dough as it warms up, shared below. 

The flour, water and ambient temperatures, weights and FDT’s for 48 dough mixes have been measured accurately (see later post on accuracy).  26 of the mixes used deliberate variations of temperatures for the standard pizza dough mix.  The intent was to get a range of results, rather than all the same.  The other 22 mixes are different bread dough mixes using both the Kenwood and Bosch mixers.  They are relevant for comparison purposes because this discussion applies to all sorts of doughs and mixers, but they are kept separate.

So the first method, which ONLY applies to similar temperature results and is “a bit dodgy” really.  The first temperature equation above for “TTemp” can be re-arranged to calculate a predicted Rheology factor for each dough mix.  This is the difference between FDT and TTemp:

Rheology factor = FDT - TTemp

So taking 18 CLOSE individual results, the average FDT - TTemp value is 3.8C.  This gives 16.4% of the FDT due to Rheology factor warming.  For these 18 doughs the average difference between FDT and PDT is -0.0027C, with a standard deviation of +1C.  10 of the dough PDT's were underestimates of FDT, 8 overestimates. 

For comparison purposes, with the other different dough / mixer combinations 20% ( 6.6C )of FDT is due to the Rheology factor for the bigger Bosch pizza dough and 21.6 % ( 4.5C ) for bread dough in the Kenwood mixer (typically 68% hydration, 50% spelt wholegrain flour, 50% white strong).

So the very simple dodgy method gives:

FDT = Ttemp *1.164  ….for the standard pizza process.

This is expanded below for cut and paste into a spreadsheet, just change the 0.164 to what fits your data best:

TTemp = (((water g * water SHC * water C) + (flour g * flour SHC * flour C)) / ((water g * water SHC) +( flour g * flour SHC))) * 1.164

Re-arranging it, you can estimate the flour and water temperatures needed to achieve the FDT.

It works. 

However.... a substantial part of the Rheology factor loosely concerns viscous particulate / molecular shearing, which is temperature dependent upon activation energy and other factors such as the change in relative dominance of colloidal particle surface charges versus mass based particulate interaction, particle size distribution, shapes and pH, etc etc, all changing with time. The details are not relevant to a pizza other than the Rheology factor is substantially temperature dependent.  Temperature is something we have homed in on and have significant control over: unlike other esoteric parameters.  The very simple dodgy method discussion above takes no account of temperature.

So the second and better way of estimating is to include temperature effects, which also allows us to use a wide range of ingredient temperatures.  For instance see the attached bar graph: this is to give a conceptual picture of how ingredient temperatures contribute to FDT.  Each vertical bar represents the temperature components of a dough at a FDT of 24C. 

The Rheology factor is at its biggest when the dough ingredients are cold:  when viscosity is high, as the activation energy is low.  Hot water can have a very big impact, etc: one can make up a few more scenarios.

To make this generalisation more explicit, the next graph shows Rheology factor (y axis) against TTemp (y axis) for 26 doughs (18 of which were used in the previous 16.4% dodgy calculation).  The others include colder doughs and one warmer dough.  The cluster of 18 doughs used in the previous method can be seen in the 17 - 22C TTemp range.

The weights of water and flour can be ignored here as the hydration of all of the doughs is the same, 62%.  A fringe benefit of holding hydration constant. 

The graph shows that Rheology factor is temperature dependent and the relationship is described by:

f(x) = 0.002977x3 – 0.1207x2 + 0.4928x + 17.95

with an accurate fit (R2 of 0.9346) 

or in user friendly form:

Rheology factor = 0.002977 * (TTemp )3 – 0.1207 * (TTemp )2 + 0.4928 * (TTemp) + 17.95

Apologies, the equation is a little messy but the value of Rheology factor cannot be zero or less so we have to use the polynomial form to avoid the x axis zero intercept, instead of an otherwise often satisfactory linear relationship.  Many of my doughs (results not used here) have a very low Rheology factor, so I need the calculation to be sensitive to this.

We can now work out how Rheology factor will enable us to obtain an accurate PDT.  As we covered earlier,

FDT = TTemp + Rheology factor

We want our PDT estimate to be accurate.  The most accurate case of our PDT estimate (limit condition) occurs when:

PDT = FDT  (i.e. our estimate is correct)

so substituting:

PDT = TTemp + Rheology factor

An example to make sense of this:

Taking the earlier example where we started with 300g of water at 15C, and 500g of flour at 23C.  This gave a TTemp = 18.1C. 

Now using the second method polynomial relationship to get the the Predicted Dough Temperature as :

PDT = 18.1 + Rheology factor

Rheology factor = 4.96

PDT = 18.1 + 4.96

PDT = 23.06C

Also you can rearrange the expanded Ttemp and Rheology factor equation to determine the water temperature to use for a given flour temperature or vice versa.  There should be enough information here for you to have a go if interested, even crank your spreadsheet to converge using Newton’s method or bisection rather that manually converge.

We do not mention or use the concept of “Friction Factor”. 

Note the rate of shear, or more or less the speed of deforming the dough, has an impact on viscosity: we have to a large degree avoided that issue as all mixing is at a constant (the lowest) speed: another fringe benefit of standardising the mix. 

Even so, the mixing modes of the “domestic standard” orbitally mounted spiral dough hook are significantly different to other mixer types and mechanisms.  The mix duration is standardised to 10m: for sure if the mix is for longer or shorter, the more / less energy will be released by the dough, and the constants above will change: but you can do it. 

Some approaches to FDT, FF and PDT include the temperature of the air as a variable.  I disagree with that approach because the SHC of air ( 1.01 kJ / kgoC ) is low compared with our flour and water (this loosely means air cannot hold much heat) but crucially the Thermal Conductivity of air is insignificant ( around 0.026 W / (moC) ).  Air is actually an insulator unless in forced flow, it cannot transfer the small amounts of heat it can hold. 

To qualify this, attached is a graph of FDT (on the vertical axis) and ambient temperature (on the horizontal axis).  The regression lines shown (linear, logarithmic and exponential) show a statistically insignificant relationship between ambient temperature and FDT (R2 of below 0.1 in all cases).  Eyeballing the graph, there is a slight increase in FDT over the whole range of temperatures, but most people operate in the FDT range of around 22C (72F) to 26C (79F): in that part of the graph, and higher, there is no relationship. 

Possibly more tricky, or not, is the heating up of the dough hook top.  When mixing the top of the hook and bayonet device get very warm to touch, and the orbital assembly into which it fits is warm to touch.  In the “olden days” mine used to get hot.  Potentially, a dough hook warmed up by the mixer orbital head / transmission system is a good conduit for transferring heat into the dough mix. 

However it is unlikely in practice.  In the dough itself, water has a Thermal Conductivity of 0.61W / (moC), and flour 0.45 W / (moC): this means in practice that the solids and liquids in dough have the Thermal Conductivity of concrete, plus the further insulation caused by the entrapment of air: aerated concrete ?  Also note the mixer head is not noticeably warm for the first half of the 10m mixing time.

On top of this, the business end of the dough hook is warm too, the central section is cool: as though there are TWO heat generation sources at play: the mixer head mechanism, and the dough / hook interaction.

Finally, some of the dough masses being mixed are a lot larger than others, so the Surface Area / Volume Ratio potentially comes into play.  Attached are graphs of dough weight versus Rheology factor, for Kenwood orbital pizza and bread doughs, and Bosch pizza doughs.  If SA / V was contributing to the temperature measure of Rheology factor, the Rheology factor (vertical axis) would vary with dough weight.  It does not. 

With commercial scale mixing, things may be very different.

To summarise, using the above approach I can make sure in advance that the 10m dough mix gets to 24C in all seasons and the dough is handed off to the cool box at 24C. 

Then hours later, the aerated dough comes out of the cool box still at 24C, ready to cook.

Now a recipe: the pulled pork one...the pork is cooked very slowly in the oven using the residual heat the day after the previous pizza session.  It is then shredded and frozen, and defrosted on the day.

Some visitors think this pizza gives the Desayuno a run for the money. 

The key with this recipe is to get the chili and pimientos to sharply cut through and balance the pork greasiness.


El Caliente Cerdo Pizza

Big big big overload pizza.  Cornicione optional.

Base of tomato: the regular base, 70g
Tierno cheese: irregular spread all over, cut as before small bits, 30g
Red Pepper: uniformly spread all over, cut fine strips, fry to soft in Jerez vinegar, 35g
Sweet white onion: uniformly spread, cut lengthwise fine strips, fry in Jerez vinegar to soft, or even coloured, 15g
Green Pepper: irregular spread, cut fine strips, fry in Jerez vinegar, 7g
You can combine the three ingredients above to cook together or not, for me with a sharp palette they are better separate.  If you really really like pulled pork, don’t bother and cook together.
Guindillo (green chilli): large size, maybe 2 medium pcs, spread irregularly all over, or if ambitious, placed into clumps, fine chop, deseeded and deveined, for surprise “notable parcels of heat” If you like your Scoville’s leave the veins and seeds in.
Pulled pork: 100g, broken up into “threads” with fork, spread all over with gaps, rough top surface not smooth, “forked up” to expose rough edges, pre cooked and pre seasoned
Optional lacon 10pcs irregularly spread
“Valle de San Juan Pallencia” mature sheep & cow cheese: small sprinkle fine chop,  5g.
« Last Edit: December 29, 2019, 10:43:43 AM by stef »


Online apizza

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Re: Project Complete…2y
« Reply #35 on: December 29, 2019, 11:10:47 AM »
Looking at the photos, was your outdoor oven installed and then uninstalled? Did I miss something?

Offline Icelandr

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Re: Project Complete…2y
« Reply #36 on: December 29, 2019, 12:14:30 PM »
Out of curiosity, would you still categorize your pizza as Neapolitan? Thanks for the posts, but they are a very long distance from my interests in Pizzamaking, I am of the “it is just street food, if you keep trying, someday it will be pretty good” camp. I hope it is as much fun for you as it is for me, enjoy your pursuit.
PizzaParty 70x70, saputo floor

Offline stef

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Re: Project Complete…2y
« Reply #37 on: December 30, 2019, 01:53:41 PM »
Hello Marty,

thank you for being eagle eyed about the pictures.

You didn't miss anything, I got my pictures out of order with the text.

So I'm just posting the next installment, where the oven pictures get the right context.


Offline stef

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Re: Project Complete…2y
« Reply #38 on: December 30, 2019, 02:28:04 PM »
Hello Icelandr,

thank you so much for your comments: yes, looking at the recipes I have posted it's fair to ask about whether Neapolitan or not.

So here are a few of my current views, of course they may be different tomorrow....:

You have seen the records of a 2 year project which had a closely defined ambition in the first post, which were:

    • Simple and predictable process
    • Understanding cause and effect
    • Data collection for improvements
    • Work with the climate: south east Spain
    • To use ingredients from Spain and Internationally
    • Use precise measurement: especially temperature and weight
    • Reduce costs: I am retired.

Sadly many years of my life before retirement involved doing things others could not do, did not know how to do, or had made an complete disaster of. 

That history has driven me to do this project: so I apologise for being somewhat formal about it !!!!

What you haven't seen is the rest.....

Every pizza session ever has had at least one absolutely standard Margherita.  Nowhere to hide with a Margherita, and so much of that is the oven. 

The sessions in the last year or so have also included a Margherita Mutation, with three specific Mutants. That will be covered in a later post, as it comes under the fifth ambition bullet point above.

I don't accept the AVPN point of view other than as an extraordinarily interesting and invaluable starting reference, and an absolutely World Class Napoli marketing exercise.

I have tried to share some aspects of local produce and palette, there is a later post specifically on that and I guess it may explain a lot of what the vignette posts cannot capture.

For me my pizzas are in the spirit of Napoli, unless you believe the AVPN marketing spiel in its entirety.  The temperatures process and dough are there.  Toppings are for debate.

Something I find nobody talks about is that wood has been an expensive fuel in the city of Napoli: many pizzas are the product of deep frying to reduce cost, not wood fired ovens.  History is whatever you choose to write.

Street food to me means the cultural exercise of deeply ingrained skills and tuned palette: based on a lot of time in Asia, without getting into the more local subject of Tapas, the most recent of which I ate a few days ago consisting of just a lemon leaf encased in a batter flavoured with cinnamon and lemon.   Street food is not an accident, or a just: it is wonderful.

Thank you for getting me going !!!   BTW I did love Indian Ice Cream on my stays in Vancouver.


Offline stef

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Re: Project Complete…2y
« Reply #39 on: December 30, 2019, 02:36:01 PM »
Part thirteen of the Pizza Project:

Cooking Time

More than five years ago we purchased a manufactured “baby” wood fired bread oven as part of  our outdoor kitchen (50cm diameter, high dome). Ovens like this and bigger are popular in Spain, where outdoor living is the norm for much of the year.

The next part of this story you can guess: one day we tried yet again to make pizzas in the bread oven, previously they had been hopeless disasters.  But this time the oven was running unusually hot.  That was that: it was the start of the Pizza experience.

18 months of basic learning later, we made the decision: we just had to have a dedicated pizza oven, it would also have to handle up to 5kg of bread dough in one session.  Lots of research took place, the information Forno Bravo provide in their ebooks was essential.  Thank you.  Photographs of Stefano Ferraro making ovens with no insulation and the thermal mass of a nuclear power reactor however were rather less useful.

The baby bread oven had to be demolished to make way for the new: the pictures were at end of last but one post (posted in the wrong order….), the second of those shows the base cleared.  The old base was incorporated into the bottom of the larger new base.

Our current oven is 80cm (2.6ft) diameter internal, with 1m front to back with the throat, 250kg thermal mass (560lbs), lots of refractory standard insulation, largely encased in regular insulation. 

The inner oven structural core made of refractory concrete was sourced from Italy directly (Alfa Pizza, Anagni, Italia: around 100km south of Roma).  It is designed for pizzas, the flattened arc mouth being only 18cm high and 44cm wide, with maximum internal roof height of 40cm, the dome curving uninterrupted to floor level (no “soldier” verticals), happily handles 430C (800F), and the core cost less than 600 Euros including shipping.  Sadly it currently costs $999 in the US at patioandpizza.com (Cupolino 80 model), and we strongly recommend it.

A factor in this choice was that it comes in 3 bits (140kg total) and we thought we would be able to lift these individually into place unaided, then increase the thermal mass up to 450Kg by adding coats of reinforced fire cement as recommended.  Guess what: 2 of the bits weighed almost nothing, and the third, the dome, was more than 100kg.  It took a few months to install it and build its housing complete with ultra-aesthetic massing and mosaic tiles.  The insulation, brick arch at the front (sourced separately) and building materials came to about the same as the oven core cost.  There are a few attached pictures showing the build.

Our fuel is a combination depending on availability of well sized orange, lemon, olive and almond logs from the log yards: these are our regional hardwoods and have high calorific values, the only practical differences we have noted are that olive is slightly more sooty, and almond is more difficult to get alight.  Orange and limon are around 10% cheaper.  We buy wood at least a year in advance, it is not green when we buy, if we are lucky it may be well seasoned. When we started this journey, we used big fat logs and wondered why nothing ever got hot. 

Log sizes we use have evolved, generally logs are now "thin" 3cm to 8cm (3 inches) in diameter, predominantly the whole branch rather than split wood (Other than almond, there is no heartwood / sapwood distinction in these trees).  The lengths are typically 30cm to 70cm, we prefer around 60cm (2 feet). 

To get up to heat, a few larger diameter logs are tucked away to the edge of the floor on our metal grate to provide a good background when up to temperature, then the thinner longer logs are used for maximum flame and light when the pizzas go in.  Cooking can start after an hour of heating, but it’s best from 1.5h onwards.  The grate is placed to one side of the oven, it allows us to get logs off the ember floor, burn on all sides and not fall into the cooking area (picture attached)  It was made from bits of BBQ and DIY store metal, and needs repairing from time to time when it deforms badly with the heat.  We had met a New Zealand pizzaiolo on our travels who gave us tips on oven management: you have to have enough flame to see.  When a log has died early we use our saved wine bottle corks to provide flame, hence light.  Our pile of corks grows faster than we can throw them into the oven though.

Temperature: for nearly every pizza cooked in the last 2 years, and many before then, we have recorded oven temperature at launch time ( floor, back wall and roof ) plus a subjective comment on the finished pizza quality, and cook time.  An analysis is incomplete, but the trends were increasing temperatures and until recently, mainly constant cook time (the mythical 90s). 

That trend has now ‘peaked’ with cook time reducing, as the higher levels of pizza char are being criticized more.  Typically it runs at 380-440C back half of floor ( 716-824F ), 413-510C back wall (close to pizza cooking area normally used, 775-950F) and 480C to >550C dome: when the IR meter goes “off the scale” (896-1022F ): these numbers are towards the high side and reflect the later part of an evening.  Substantially lower does not give us the yummy NP pizza factor.  These temperatures are approximations, they vary a lot and the IR meter is only known to be accurate to 100C.

We have 1.5m length Lilly Codroipo oven tools (From Codroipo, Italia, NE of Venezia, lillycodroipa.com), also a home made steel blowpipe with a foam pipe insulator mouthpiece to clear ash dust off the floor better than the brass brush (picked this tip up in India, where they use bamboo blowpipes) and a home made “push puller” with a 25 x 5cm aluminum blade at right angles to an aluminum pipe.

It has been a story of trial and error, even if we had received expert advice, I’m not sure how much more quickly we would have got to this point.  The oven and tools work reliably, week in week out.

No recipe today, just our replacement horno (oven).

The first construction picture shows the new base being made on the location of the baby oven.  The new base is extended forward and sideways, and cutting back into the tiled walls to get extra clearance for insulation.  The vermiculite concrete can be seen in the central area of the base floor.  Vermiculite from the Garden Centre, concrete shuttering from the palette the oven was delivered on, and bits of a garden gate.

The second picture has the oven core in place, with the concrete shuttering removed.  It was a massive job to get the core lifted up using three ladders.  It is sitting on a 5cm pad of silica refractory insulation, coated in runny cement to protect it whilst the core was being moved into place.  The first two refractory bricks for the arch are approximately positioned.  You can see the curved front of the refractory concrete floor:  I wish that was not curved, but we got past it.  The idea for the brick arch was ours as we did not think the core design would pull smoke efficiently before the oven gets hot.  It has worked functionally and aesthetically, but was expensive due to the shape of the refractory bricks.

The third picture shows the start of the core being coating with fire cement, with just chicken wire reinforcing at this point.  The refractory insulation blanket is visible at the edges where it had to be positioned early due to the tight fit with the walls.  The 1.2m long “one holer” terracotta bardo is to be used as part of the outer casing: we see the same type of bardo used by Stefano Ferraro to form his flue pipe above his oven mouths.  At the front we are starting to build up concrete levels towards the floor level.

The fourth picture looks more interesting: the arch has been built by hand, using a home made styrofoam former.  Note the arch keystone brick is tight against the adjacent bricks: it had to be malleted in with “some force”.  The stainless steel flue has been positioned, just out of sight it turns to the right and feeds into the big chimney above the adjacent BBQ / paella station (the rectangular cutout in the tiled wall can just be seen).  The fire cement layers have been finished, with buried 5mmm rebar wrapped around the core at two levels, including to tie-in the arch, which also has two side to side rebar lengths behind it to further bond the arch to the core.  Concrete has been build up at the front, leaving a gap to insert a curved section of stainless steel to protect the final floor edge.

The fifth photo shows three bardos built up, with the diagonal join to eventually form a curved corner (you can see the curve was defined for the concrete base formwork: we used an old plastic rain gutter to get the shape).  The front is being formed using mortar mixed with “cola” (you may know it as swimming pool mosaic tile powder adhesive: here it is used to stick anything together as a glue.  On top of the upper bardo 1cm rebar has been positioned horizontally and drilled in to the right hand tiled wall.  This will support the”lid” of the horno and prevent the top layers of insulation being compressed.

The sixth picture is the fully built version 1: refractory insulation has been topped with rock wool (not able to take high temperatures so positioned outside the refractory blanket), the bardos have been cemented / glued in including the roof, the pillars at the front below the base have been given a cosmetic extension to provide a more satisfying form, everything has been rendered with cola to build out the corner curve and tie in the the steel protecting the floor edge, then the swimming pool mosaic tiles have been cola’d on and grouted.  Stainless steel angle bead has been used on the exposed front pillar corners to protect the mosaic.  You can see the chimney to the top left of the photo.

On the last photo you will see the detail of the arch and steel floor edge.  The floor join to the curved front of the oven core is barely visible.  The arch key brick now has pointing to either side of it: a trick by cutting out a slot in the brick then infilling it with pointing cement. 

Updates since include a later infill of the gap between the top of the horno and the tiled roof lintel above, the outside kitchen ceiling has been extended forward 3m, and the tile work surfaces replaced with granito, and stained wooden doors fitted beneath.  One day the Arabian tiles above the horno will be replaced, as they don’t visually work.

My partner and I did the entire installation.  The form of the horno object as a whole is deliberate.  The asymmetry is actually due to the oven “cutting in” to the right hand wall (which was cut back), we took advantage of that.