Author Topic: Ratio for top and bottom oven temperatures  (Read 4558 times)

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Offline jamieg

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Ratio for top and bottom oven temperatures
« on: July 13, 2012, 11:39:20 AM »
What if I could specify the exact temperature for both the bottom and top of the oven?

Can anybody recommend a ratio between top and bottom - bearing in mind the followiong conditions -

- the height of the oven is about 4 inches
- the oven is gas powered with a metal frame
- the pizza will be cooked directly on the stone floor (no screens)
- the flour is not Caputo (it's bread flour with 12% protein) - it tends to burn a little at very high temp
- hydration 70% (bear in mind the flour is dryer than Caputo - so itís more like 60%
- the cheese is dry mozzarella

The advice Iíve received so far is 330-350C on the base and 400C+ on the top.

Thank you,

jamie


Offline scott123

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Re: Ratio for top and bottom oven temperatures
« Reply #1 on: July 13, 2012, 12:58:51 PM »
Describe the 'stone floor' Thickness? Material?

Offline jamieg

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Re: Ratio for top and bottom oven temperatures
« Reply #2 on: July 13, 2012, 04:45:02 PM »
Sorry, it's brick, not stone.

I'm guessing it's thickness is about 2 inches.

I don't know more than that - but I can take some photos on Sunday.

On Sunday - I will have probably my last practice in the oven - before it is installed in my restaurant - at which point I will have maximum 2 hours to get the pizzas right.

I'm fighting the problem of over-cooking the base and/or top while the borders remain un-charred and without character. It's not a problem I have in my existing oven - where there is plenty of side-on heat.

Any help very much appreciated.

jamie

Offline scott123

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Re: Ratio for top and bottom oven temperatures
« Reply #3 on: July 13, 2012, 05:31:56 PM »
Jamie, when you've set the oven to 330 on the bottom and 400 top, which part of the pizza overcooks faster?  In what time frame is it overcooking?

When the top overcooks, is the cheese browning too much or does the top of the rim burn as well?

How long are you preheating the oven for?  If the hearth is, indeed, 2" firebrick, you need at least 2 hours to pre-heat, and quite a bit more if the oven isn't very powerful. A fully pre-heated oven will go a long way in providing even heat.

Is this the oven you linked to a while back?  Do you have correct specs?  As I said before, it's not physically possible for this oven to be .12KW.

Previously you mentioned working with 79% hydration. Have you lowered it to 70% now?

A while back you were using sourdough.  You're strictly IDY now, correct?

Offline jamieg

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Re: Ratio for top and bottom oven temperatures
« Reply #4 on: July 13, 2012, 05:58:58 PM »
Hi Scott,

I really do appreciate your interest.

The last time I tested the oven - I set the floor to 400c and the pizza base had a yellow burning colour within about 15 to 30 seconds.

The top was set to 400c and the cheese dried out while the borders remained 80% cooked without colour. Unfortunately, I canít give you much information on time - my guess is that this happend in about 2 minutes.

The oven was pre-heated for about 30 to 45 minutes.

Yes, this is the same oven I linked to some time ago.
http://www.citalsa.com/files/horno_pizza_pr-212_06001051.pdf

Actually, I have no idea what .12KW. refers to.  Thereís a good chance that there are typos in the specificastions - as frankly it happens all the time with documentation in Colombia.

But, Iíve been assured that the oven can reach 500c. In any case, even if it falls a little short - Iím now convinced that my flour cannot handle temperature any higher than 350c - to 380c - at least on the floor.

My current hydration is 77%. I can go as low as 70% - but any lower than 70% - and the flour is incredibly hard to mix with the water - and the resulting rise in the pizza border is significantly less.

Yes, Iím only using IDY at the moment. I hope to use sourdough - but for the moment I donít want to complicate things by adding another variable.

As you may have seen in my other posts - Iíve become fixated by the idea that I wonít be able to cook the borders correctly without a good amount of side heat - although the information on this forum would suggest Iím wrong. I hope I am.

The obvious solution might be to lower the hydration - although Iíve read so many times that hydration is a critical factor for good oven spring.

Offline scott123

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Re: Ratio for top and bottom oven temperatures
« Reply #5 on: July 13, 2012, 07:53:47 PM »
Jamie, I'm going to throw out a bunch of theories here, because there's a few odd things going on. Everything I'm asking is important, so please try to answer all the questions to the best of your ability.

Is this exactly the same flour you were using with the clay oven?  If it was, how long have you been using it and has it always been consistent?  Did it ever give you the yellowing that you're getting now with the clay oven? Is this a reliable flour miller and distributor? Is there any chance the flour got wet or wasn't stored properly?

Do you have other bread flour options?

Please list the ingredients of the flour.

Are you testing the hearth temps with an IR thermometer?

This is a brand new oven, correct? Have you cleaned the stone hearth? Are there any odors coming from it during the pre-heat?

I know it's coming down to the wire here, but, in order to understand what's going on, photos of the oven would be huge help.  A close up of a stone would help, especially if you can lift the stone out and show the thickness.  A shot of the broiler element is critical.

When making pizza dough, when you combine water and flour, it should be stirrable for a few seconds and then become impossible to stir. At the point where it becomes impossible to stir, you knead it. If a lower hydration dough isn't rising properly for you, we need to look at other factors, such as gluten development, yeast quantity, salt quantity and fermentation.

Hydration is critical for oven spring, but you can always have too much of a good thing.  This is a dry flour- perhaps as much as 3-5% less water than American flour.  12% protein flour should have an absorption value around 60%, though, so to compensate, you probably shouldn't be that much north of 65%.

Are you located on a mountain or at high elevation?

We need photos of the cheese.  Both pre-bake (shredded) and post-bake, as well as a shot of the cheese in the packaging. Is there a temperature where the cheese will melt and then bubble?

Pizza diameter? Dough ball weight? Sauce quantity per pie? Cheese quantity?

Offline jamieg

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Re: Ratio for top and bottom oven temperatures
« Reply #6 on: July 15, 2012, 11:30:18 PM »
Hi Scott,

My apologies for throwing so much information back at you - a lot of which might be irrelevant.

Before, I answer your questions - let me tell you the outcome from the trials I did in the new oven today.

I cooked 3 pizzas with varying top and bottom burner temps. The cook time was approximately 2.30 seconds.

- bottom 300c / top 400c
By the time the base was cooked to the max - the borders were cooked through but with absolutely no colouring at all.

- bottom 275c / top 400c
A slight improvement - the borders had some colour - but minimal.

- bottom 250c / top 400c
The borders had an allround brown/golden colour and a little crunch. No leoparding.

Iím surprised I needed to go as low as 250c on the floor to get the borders cooked. Of course, I need to try going 500c on the top which will probably allow me to raise the floor temp a little.

Although Iíve finally managed to get a temperature balance that allows me to cook an edible pizza - Iím still baffled by the difference between the pizza cooked in my existing clay oven with good leoparding and the pizza cooked in the new oven with zero leoparding although more crunch.

Below is some information based on the questions you asked me.

FLOUR
Iím using the same flour in both ovens. Iíve been using it for about 4 months. If my clay oven is maxed out - I get the same yellowing problem. Actually, Iíve had the same yellowing problem before with other flours - so I donít think itís the flour.

The flour miller and distributor are very reliable. I could probably improve my storage as the bags of flour are kept undernieth the oven - where it is slightly warm - but never hot. The flour is not wet/damaged.

Here are the ingredients:
protein 12%
fat 1.10%
fibre 0.45%
carbs 0.76%

vitamin b1 6mg/kg
vitamin b2 4mg/kg
niacin 55mg/kg
folic acid 1.54mg/kg
iron 44mg/kg

OVEN
I have no way of testing the hearth temp of my clay oven - iím guessing itís about 350c - purely based on feel. Similarly, I havenít tested the temperature of the new oven with an independent thermometer - although obviously it has its own temperature dial and thermastat.

Iíve tested the oven brand new in the store and also in a nearby restaurant where they are very happy with it. That said, the restaurant use a perfurated screen so the pizza isnít touching the floor - and their base is like a flat dry pancake - not something that I want to copy.

There are no strange odours coming from the oven.

DOUGH

flour 2400 gr - 100%
water 1800 gr - 75%
water 50 gr - 2%
salt 80 gr - 3%
IDY 125 ml - less than 1%

I mix by hand.

Firstly, I mix cold water, flour and IDY. After about 5 or 6 minutes - or when Iím convinced all the flour is Ďwetí - I let it rest for 30 minutes.

I then add salt and cold water and squeeze it into the dough until it is evenly distributed.

I then Ďkneadí the flour - which basically consists of gentle stretches and folds - for at least 5 minutes until the dough is very soft and smooth.

The dough then rests for approx 7 hours at room temperature - which obviously various quite a lot - but is approximately 70F.

The dough is then balled and put into individual plastic containers and in a fridge set to 16c.
The balls stay refridgerated for between 24 to 72 hours.

Balls are 250gr and the resulting pizza is about 11 inches.

MOUNTAINS
YES!  Iím in Medellin. Medellin is basically in the mountains at 1500 meters (about 4921 feet).

OTHER THOUGHTS
Iíve noticed 2 strange things about my recipe.

My hydration is 77% and Iím very happy with the way the dough handles. If I try to go as low as 64% - its very difficult to get all the flour to mix with the water.

I use a VERY small amount of yeast - 125 ml - which is so small I canít reliably weigh it on a digital scale in gr - so I use a measuring spoon. I guess itís about 5 gr - which must be around 0.002%.  Of course, Iíve played around with other recipes using a higher amount of yeast - but I found that using too much caused the balls to rise too much over the 3 days that they are in the fridge waiting to be used.

PHOTOS
Tomorrow I hope to be able to post photos of both ovens and the resulting pizzas.

CONCLUSION
My current thinking is that - Iím being prevented from cooking at high temps because of the type of flour I use - and I will not get leoparding unless I cook at higher temps OR have a lot of side on heat effectively blow torching the borders.

Thanks again for your interest - you've forced me to think about things I would otherwise have missed.
« Last Edit: July 15, 2012, 11:36:22 PM by jamieg »

Offline La Sera

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Re: Ratio for top and bottom oven temperatures
« Reply #7 on: July 16, 2012, 12:21:27 AM »
I recommend you try a digital measuring spoon for yeast. They measure down to 0.1 gram.

http://www.amazon.com/idkitchen-Digital-Measuring-Spoon/dp/B007UXVMSY/?tag=pizzamaking-20

Offline sub

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Re: Ratio for top and bottom oven temperatures
« Reply #8 on: July 16, 2012, 04:36:19 AM »
Hi jamie,

Can you lift up the bricks like on the picture ?



Offline TXCraig1

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Re: Ratio for top and bottom oven temperatures
« Reply #9 on: July 16, 2012, 08:54:19 AM »
Are you sure about 125ml (milliliters?) of IDY? That would be about 25tsp or 71g.

What is the smallest amount your digital scale can measure reliably?
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Offline The Dough Doctor

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Re: Ratio for top and bottom oven temperatures
« Reply #10 on: July 16, 2012, 09:20:17 AM »
Jamie;
I think I know what your problem is. Your flour is milled to a very high level of starch damage. You will note that the ingredients shown on the flour bag indicate that the flour is enriched, but has no other treatment, including malting, which if present, would be indicated by the presence of malted barley flour. Also, when flour is milled to a high level of starch damage it exhibits a very high absorption, as you have indicated. The reason why malt is added to the flour is to convert starch to sugars for yeast to feed upon, and to provide some residual sugar for crust color development. With your long fermentation time your yeast is probably struggling due to lack of nutrients to feed upon. If you were to add malt or any form of amylase enzyme to the dough it would literally turn into a liquid after a few hours of fermentation as all of the damaged starch would be hydrolyzed to sugar. My recommendation is to add some sugar to the dough, this will provide both nutrient for the yeast and residual sugar for crust color development. You will need to experiment to find the right amount of sugar to add, but I would begin with an addition of 3% based on the total flour weight.
Tom Lehmann/The Dough Doctor

Offline jamieg

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Re: Ratio for top and bottom oven temperatures
« Reply #11 on: July 16, 2012, 10:28:09 AM »
Hi jamie,

Can you lift up the bricks like on the picture ?




It sounds like that might be a solution to increase sideways heat.  I imagine it would be possible to lift the brick floor - but I've no idea if I could also lift the burners.

I will investigate.

:-)

Offline jamieg

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Re: Ratio for top and bottom oven temperatures
« Reply #12 on: July 16, 2012, 10:31:35 AM »
Are you sure about 125ml (milliliters?) of IDY? That would be about 25tsp or 71g.

What is the smallest amount your digital scale can measure reliably?

Good point.

My measuring spoon reads: 1/4 tsp / 125ml.

I realise I have no idea why it says 125ml.  1/4 tsp would seem pretty accurate.

My digital scale seems reliable after about 10 gr. For example, 1/4 tsp of IDY does not register even 1 gr.  I have to go to about 1.5 tsp to get to 1 gr.
« Last Edit: July 16, 2012, 10:54:37 AM by jamieg »

Offline jamieg

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Re: Ratio for top and bottom oven temperatures
« Reply #13 on: July 16, 2012, 10:45:08 AM »
Jamie;
I think I know what your problem is. Your flour is milled to a very high level of starch damage. You will note that the ingredients shown on the flour bag indicate that the flour is enriched, but has no other treatment, including malting, which if present, would be indicated by the presence of malted barley flour. Also, when flour is milled to a high level of starch damage it exhibits a very high absorption, as you have indicated. The reason why malt is added to the flour is to convert starch to sugars for yeast to feed upon, and to provide some residual sugar for crust color development. With your long fermentation time your yeast is probably struggling due to lack of nutrients to feed upon. If you were to add malt or any form of amylase enzyme to the dough it would literally turn into a liquid after a few hours of fermentation as all of the damaged starch would be hydrolyzed to sugar. My recommendation is to add some sugar to the dough, this will provide both nutrient for the yeast and residual sugar for crust color development. You will need to experiment to find the right amount of sugar to add, but I would begin with an addition of 3% based on the total flour weight.
Tom Lehmann/The Dough Doctor

Hi Tom,

Just to be absolutely clear - which of my 2 problems would adding sugar fix?
- not being able to cook at high temps (presumably because of the flour)
- not getting leopard spots

I've avoided adding sugar - as I previously read that - a surgery dough is more likely to turn a golden/brown colour - as opposed to staying relatively white with leopard spots - which was my preference.

That said, if sugar can add a little crunch - perhaps I can strike a balance between the 2 extremes.

Thanks,

jamie

Offline jamieg

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Re: Ratio for top and bottom oven temperatures
« Reply #14 on: July 16, 2012, 10:56:06 AM »
I recommend you try a digital measuring spoon for yeast. They measure down to 0.1 gram.

http://www.amazon.com/idkitchen-Digital-Measuring-Spoon/dp/B007UXVMSY/?tag=pizzamaking-20


Looks fantastic!

:-)

Offline TXCraig1

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Re: Ratio for top and bottom oven temperatures
« Reply #15 on: July 16, 2012, 11:19:46 AM »
Good point.

My measuring spoon reads: 1/4 tsp / 125ml.

I realise I have no idea why it says 125ml.  1/4 tsp would seem pretty accurate.


I bet it says 1.25ml.

Correction: 1tsp 1/4 tsp = 1.23ml

CL
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Offline jamieg

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Re: Ratio for top and bottom oven temperatures
« Reply #16 on: July 16, 2012, 11:41:47 AM »
I bet it says 1.25ml.

1tsp = 1.23ml

CL

Haha. Well, they forgot to put the decimal point. This is Colombia afterall or maybe it's just blindingly obvious and I'm a dimwit.

Offline jamieg

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Re: Ratio for top and bottom oven temperatures
« Reply #17 on: July 16, 2012, 12:33:44 PM »
Hi jamie,

Can you lift up the bricks like on the picture ?




Hi Sub,

Did your oven have a burner below the brick floor?  If so, looking at the photo - can I assume you were not able to move it.

Or does the oven work perfectly well without a bottom burner?


Offline sub

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Re: Ratio for top and bottom oven temperatures
« Reply #18 on: July 16, 2012, 04:43:33 PM »
Hi Jamie,

No it is not my oven,

It's an electric one with heating element on the bottom but it is a common mod I've seen on Italian forums to prevent to bottom of the pizza to end up burned, they also put an aluminum foil in the preheating

the baking time are reduced and the pizzas looks better too, look here

Offline jamieg

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Re: Ratio for top and bottom oven temperatures
« Reply #19 on: July 18, 2012, 12:27:53 AM »
So, anyway here are some photos of the 2 different ovens and the resulting pizzas - starting with the existing clay oven - followed by the new oven.

Obviously - in both cases - the dough is exactly the same.


 

pizzapan