Author Topic: fermentation  (Read 9761 times)

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Offline IEatPizzaByThePie

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fermentation
« on: January 16, 2007, 04:08:02 PM »
I've made a good number of pizzas, and I can definitely say that I prefer the taste of retarded dough that has fermented for a good 3 days. That is compared to dough fermented for 6-8 hours, 24 hours and 48 hours.

My question is, what exactly is the resulting difference between a dough that ferments for, say, 8 hours at room temp and has risen to double its original size, and a dough that ferments refrigerated for 3 days and has doubled in size? Does the fermentation occur more "thoroughly" in dough that uses a slow ferment even though the rise appears to be the same?
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Offline LabRat

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Re: fermentation
« Reply #1 on: January 16, 2007, 05:01:50 PM »
My understanding is that retarding the dough slows down yeast fermentation, which allows amylase and other enzymes naturally present in flour more time to break down starch molecules in to various sugars and perform other functions.  Bacteria also present in the flour are adding their own fermentation products (like acids) during this time, but if you let it go too long they take over and create an environment in which bakers yeast can not survive.  The wild yeast in San Francisco sourdough starter actually prefer the acidic environment created by the various bacteria.

Offline SemperFi

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Re: fermentation
« Reply #2 on: January 16, 2007, 09:05:55 PM »
Ieatpizzabythepie,

You might want to check out this thread by Pete-zza.  He is extremely knowledgeable on pizza doughs.

http://www.pizzamaking.com/forum/index.php/topic,1523.msg13899.html#msg13899

Hope it helps.
Adam
Adam

Offline Pete-zza

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Re: fermentation
« Reply #3 on: January 16, 2007, 09:17:40 PM »
Adam,

Thank you very much but the guy who really knows what is going on inside a dough ball is November :).

It was interesting to read the thread you referenced because at the time many of us were having difficulties getting more than three days out of a Lehmann NY style dough. More recently, with the help of November and others, I have been able to make doughs that have a useful life of 6-12 days. The details, along with photos, are presented at this thread: http://www.pizzamaking.com/forum/index.php/topic,3985.msg33251.html#msg33251.

Peter

Offline SemperFi

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Re: fermentation
« Reply #4 on: January 16, 2007, 09:22:34 PM »
Peter,

Your welcome, I do believe that you deserve kudos though.  I had actually just scanned that thread, then did another search, and came up with the thread that I posted.  Both are excellent threads though.  Its amazing, I just keep searching every thought that comes to mind, and there you are..with a post.   :-D  Thanks again for the additional info Peter.

Adam
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Offline IEatPizzaByThePie

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Re: fermentation
« Reply #5 on: January 17, 2007, 04:05:49 AM »
Thanks for the replies.

Yes, I'm very away that Pete is extremely knowledgeable  ;D
After spending any amount of time on these boards it quickly becomes apparent that this guy is a natural born pizza wiz! Like you, his posts always seem to turn up in my searches (that's a good thing!)

Anyway, I will have to experiment with that 5-6 day Lehmann recipe in that thread. I've made the original Lehmann NY recipe already, but it only refrigerated for 24 hours. It was good, but personally I enjoyed Big Dave's Old Faithful more.
"I looked at the serving size: two slices. Who the hell eats two slices? I eat pizza by the pie! Two pies is a serving size!!"

Offline November

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Re: fermentation
« Reply #6 on: January 17, 2007, 05:48:29 AM »
Thanks, Peter.  When I first saw the question, I hesitated answering because of how subjective flavor can be.  A lot of people swear by cold-fermentations; I don't.  This topic depends on so many things it's not even funny.  (Okay, maybe it is sometimes.)  This is by no means a comprehensive answer on the subject, but here are a few important points, some of which LabRat mentioned already.

Bacteria convert malic acid excreted by yeast into more pleasant tasting lactic acid, and bacteria are more active than yeast at lower temperatures.  Acetic acid bacteria also convert flavorless ethanol to acetic acid.  However, if the yeast are not producing these chemicals at a very fast rate because of the cold, the bacteria aren't going to be doing their job as actively as they could.  Also, alpha-amylase enzymes, like all enzymes, are almost as inactive in the cold as yeast.  If you want to know more specifically how active the enzymes are with any given condition, search for the Arrhenius equation (an equation used in Chemistry to determine reaction kinetics).

For maximum flavor the trick is, as most chemistry experiments go, to find the reaction stoichiometry between bacteria, enzyme, and yeast activity.  You want the dough at just the right temperature so that they all play their important roles harmoniously.  It's not as easy as just putting the dough in an average household refrigerator.  How much bacteria you have in your dough, the falling number of your flour, the strain of your yeast, and the micro-nutrients you (purposely or inadvertently) feed your yeast all have more to do with flavor than the temperature itself.  Cold fermentation has house odds only because of its near fool-proof procedure.  When doughs can go as long as a week in the refrigerator, pulling it out to use a few hours late isn't going to have much effect.  The same cannot be said about room temperature dough.  One has to be more careful with what goes in the dough, and when to use the dough.

- red.november

Offline SemperFi

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Re: fermentation
« Reply #7 on: January 17, 2007, 06:27:10 AM »
Wow, Pete-zza was right when he said:

Thank you very much but the guy who really knows what is going on inside a dough ball is November .




Bacteria convert malic acid excreted by yeast into more pleasant tasting lactic acid, and bacteria are more active than yeast at lower temperatures....  Also, alpha-amylase enzymes, like all enzymes, are almost as inactive in the cold as yeast.  If you want to know more specifically how active the enzymes are with any given condition, search for the Arrhenius equation (an equation used in Chemistry to determine reaction kinetics).

- red.november
Adam

Offline IEatPizzaByThePie

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Re: fermentation
« Reply #8 on: January 17, 2007, 06:52:17 PM »
Thanks for that post November, very informative. A lot seems to be going on during fermentation that many people probably don't know about.

So, is there any reason why I couldn't just take a given recipe, lower the amount of yeast some, and then refrigerate the dough longer to achieve a slower rise? Like a 3 day rise instead of just 24 hours maybe? If this is possible, would anything else need to be altered to compensate for the longer rise time (such as other ingredients like the amount of water)?
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Offline November

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Re: fermentation
« Reply #9 on: January 17, 2007, 07:28:19 PM »
IEatPizzaByThePie,

The length of fermentation, whether cold or room temperature, is always determined by what you have in your dough that will help sustain the yeast.  This includes several things, the most basic of which is nutrients.  Simple nutrients like sugars are obviously needed, whether added by you or converted by enzymes.  You'll likely want to use a little less salt than a room temperature dough formula, because although the yeast already slow down because of the lower temperature, enzymes are even more inhibited by salt.  If you're planning on a really long fermentation, use sea salt so that additional micro-nutrients are available to the yeast for cell maintenance; and if you use sugar, use one with minerals like zinc, magnesium, or phosphorous (e.g. brown sugar, maple sugar, raw cane sugar, honey).  Depending on the condition of your flour, you can probably sustain a small amount of yeast (0.25% or less) for about a week at 41 F with no additional nutrients.  For a three day rise, you shouldn't have to do anything but use less yeast.

How the dough is stored in your refrigerator will make a difference too.  Ideally during a long, cold rise, you want the excess gas to escape, but not the moisture.  During a 24 hour rise, keeping it completely sealed is fine.  Storing the dough in a plastic container (as opposed to metal or glass) will spare the surface of the dough from extreme temperature gradients.  If your refrigerator is really cold like mine, where the temperatures reach 32 F or below near the back, double-up your container.

- red.november
« Last Edit: January 17, 2007, 07:30:11 PM by November »


Offline IEatPizzaByThePie

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Re: fermentation
« Reply #10 on: January 18, 2007, 08:26:48 AM »
Hey November,

That makes good sense. You mentioned letting the gases escape during a lengthy cold rise. How would you recommend going about this? Would just uncovering the container for a few seconds every day get the job done?
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Offline David

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Re: fermentation
« Reply #11 on: January 18, 2007, 09:13:13 AM »
Bacteria convert malic acid excreted by yeast into more pleasant tasting lactic acid, and bacteria are more active than yeast at lower temperatures.  Acetic acid bacteria also convert flavorless ethanol to acetic acid.  However, if the yeast are not producing these chemicals at a very fast rate because of the cold, the bacteria aren't going to be doing their job as actively as they could.  Also, alpha-amylase enzymes, like all enzymes, are almost as inactive in the cold as yeast.  If you want to know more specifically how active the enzymes are with any given condition, search for the Arrhenius equation (an equation used in Chemistry to determine reaction kinetics).

For maximum flavor the trick is, as most chemistry experiments go, to find the reaction stoichiometry between bacteria, enzyme, and yeast activity.  You want the dough at just the right temperature so that they all play their important roles harmoniously.  It's not as easy as just putting the dough in an average household refrigerator.  How much bacteria you have in your dough, the falling number of your flour, the strain of your yeast, and the micro-nutrients you (purposely or inadvertently) feed your yeast all have more to do with flavor than the temperature itself.  Cold fermentation has house odds only because of its near fool-proof procedure.  When doughs can go as long as a week in the refrigerator, pulling it out to use a few hours late isn't going to have much effect.  The same cannot be said about room temperature dough.  One has to be more careful with what goes in the dough, and when to use the dough.

- red.november

Thanks for this insight red.november .I have to say I often have a difficult time getting my head around the mathematical  / scientific side of Pizza making and as such my progress is somewhat sloth like.Particularly as someone who only uses room temp.rises / natural starters,I would value you input and  knowledge of any experimentation on the maculation of the crust that you would wish to share?It is a subject that has been touched on in the past,but without any significant explanations IMO.
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Offline Pete-zza

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Re: fermentation
« Reply #12 on: January 18, 2007, 09:25:10 AM »
November,

I understand that there are also nutrients in water that are used by the yeast. Is there any particular form of water (e.g., spring, tap, bottled, etc.) that is preferred? I know that many pizza operators, especially the big ones, use water purification systems. What aspects of the water are they treating?

The municipal water where I live is on the hard side, with a pH on the high side. I have read that using a bit more yeast can compensate. Does that make sense?

Thanks.

Peter

Offline November

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Re: fermentation
« Reply #13 on: January 18, 2007, 12:12:49 PM »
IEatPizzaByThePie,
You could do that if you're dedicated enough.  If it's just a cheap container, you could also drill a tiny hole (1-2 mm) near the lid and be sure your dough ball is oiled.

David,
I'm not sure what you mean.  Are you talking about blisters?  If so, that's been covered in another thread.  If you're talking about some other kind of lesion or surface effect, you'll have to explain further.

Peter,
Tap water is too much of an unknown and not considered a control.  For chemistry experiments at least, a chemist always starts with distilled water and adds what he needs.  In the case of pizza making, I always start with filtered water and add what I need.  Hard water has lots of minerals, but in most places they are mostly calcium and iron which yeast don't really need (at least until they develop hemoglobin and a skeletal structure).  If you weren't planning on adding sodium salt (table salt), calcium chloride (not calcium oxide) from hard water would then, and only then, be a benefit.  Spring water is a great option, since there shouldn't even be trace amounts of chlorine or fluorine.  Reverse osmosis filtering eliminates mineral content and reduces the number of larger microorganisms.  If the filtration system has a carbon post-filter, halogens are also reduced.  A water filter pitcher (like what I use) reduces mostly halogens and only part of the minerals.  I prefer filtered over bottled, because unless I run an analysis on the bottled water, I don't really know what's in it.  Yeast want a low pH (acidic), and the best range is around 4.2-4.6.

- red.november

Offline David

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Re: fermentation
« Reply #14 on: January 18, 2007, 12:32:36 PM »


David,
I'm not sure what you mean.  Are you talking about blisters?  If so, that's been covered in another thread.  If you're talking about some other kind of lesion or surface effect, you'll have to explain further.


- red.november

Yes.Leopard spots.I've seen pizzas with pale (In comparison to the rest of the cornicione) blisters but this is not what I'm talking about.The charred spotting that is so prominent against the pale dough as found in true Neapolitan pizza.I'm wondering if this is more due to the intense heat ,dough management,or a combination of factors?
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Offline November

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Re: fermentation
« Reply #15 on: January 18, 2007, 12:57:56 PM »
David,

Charing is a result of intense or prolonged heat.  The fact that it's spotted just indicates that some parts of the dough dry out sooner than others.  That can happen due to several factors, the most prevalent of which is dynamically constant circulating heat over turbulent surfaces.  The pizza crust is not perfectly smooth.  Where there are very small (almost naked to the eye) cavities, a boundary layer is created and prevents the hotter, circulating air from reaching it.  Hotter circulating air and radiant heat can more effectively penetrate places on the crust where there are small protrusions.

- red.november

Offline scott r

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Re: fermentation
« Reply #16 on: January 18, 2007, 01:40:20 PM »
November,  have you read Baking science and technology by E. J Pyler?

I was thinking about picking it up for some light sunday reading.  ;D

Just wondering if you have any comments about it.

Offline November

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Re: fermentation
« Reply #17 on: January 18, 2007, 02:19:08 PM »
scott,

No, I have not.  I had a formal education in biology, chemistry, and physics and only keep references like the "CRC Handbook of Chemistry and Physics" around.  When I want to focus on a specific discipline within one of those sciences, I turn to research publications because they are generally more up-to-date.  Publications from authors like Dr. T. van Vliet (http://www.wewur.wur.nl/wewur/visitecard.cfm?o_nummer=14942) are what pique my interest.  Read through his entire list of publications and you'll see what kind of level I like to play on.  I get most of my publications from ScienceDirect, and more specifically from the Journal of Cereal Science (http://top25.sciencedirect.com/?journal_id=07335210) for dough related research; and from Blackwell Synergy (http://www.blackwell-synergy.com/).

I'm sure "Baking Science and Technology" is a good book.

- red.november

Offline scpizza

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Re: fermentation
« Reply #18 on: February 10, 2007, 11:05:04 AM »
This is a good discussion.  November, do you have any insights on the optimal rise temperature (for flavor) for the Ischia and/or Camaldoli starters using Caputo 00 Pizzeria?

One way I recently tried to improve flavor is by attempting to increase lactic acid production.  I did this by incubating my starter through several washings at 33C.  According to the temperature graphs in Ganzle, et. al. this should shift the population in favor of L. Sanfranciscensis over C. Milleri.  Indeed the resultant culture smelled non-yeasty and dull-sour.

Unfortunately dough made with the culture, rising at 25C, showed no improvement in taste and actually lacked flavor.  I wonder if the interdependencies between the two organisms, such as the malic acid link you mention, kept the LAB from doing anything in excess of the proportion of yeast and thus defeated my skewing of the population.

I am also vexed by conflicting information in regards to the favorability of lactic vs. acetic acid for improved flavor.  Some information says lactic acid is preferable in that its non-volatility means it doesn't evaporate at baking; plus the lactic taste is more appealing than the acetic vinegary taste.  Other information points out the tongue is not where the complex tastes are registered; it's actually the nose, and thus the volatile compounds like acetic acid are preferable over lactic acid.  What are your thoughts?
« Last Edit: February 10, 2007, 11:13:17 AM by scpizza »

Offline AKSteve

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Re: fermentation
« Reply #19 on: February 11, 2007, 02:03:48 AM »
Anyone,

Any ideas on what effect the longer fermentation period has on the glycemic index of the dough? I'm a Type I diabetic and I've noticed that the pizza I make at home raises my bloodsugar much less than pizza from the local shops. I'm sure there are many other variables in play like pizza-sauce ingredients, thickness of the crust, etc. Plus the fact that I'm running around burning calories doing all of the cooking rather than waiting for the pizza to be delivered. I'm just wondering whether a 3 day+ cold fermentation would use up more of the starch in the dough compared to a quick room-temperature rise.

Steve


 

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