Author Topic: Re: Blistering in a Pizza Crust (Split Topic)  (Read 14792 times)

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Offline November

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Re: Blistering in a Pizza Crust (Split Topic)
« Reply #60 on: January 06, 2009, 11:09:07 AM »
The question of blistering was raised again recently at the PMQ Think Tank, which prompted Tom Lehmann to join the ranks of those who believe that a dry dough is the cause
:-D  Dry dough?!  I used to get those "blisters" when I worked with 80% hydrated dough.  If "blisters" form because 80% hydration is too dry, I'm the United Nations ambassador to Canada's tropic island province.

- red.november


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Re: Blistering in a Pizza Crust (Split Topic)
« Reply #61 on: January 06, 2009, 11:31:18 AM »
November,

I thought I would get you out of your chair on this one :-D. When I read that dough dryness was a possible cause of blistering, it was in the context of surface dryness, which is what Tom seems to be saying. I thought that you would know what effects flow from dry doughs based on your prior work experience at Little Caesar's where, if my memory serves me, the dough was allowed to sit around uncovered for some time. I would think that you would have seen blistering under such circumstances. If surface dryness is the cause of blistering, I would think that it would be fairly easy to test that possibility, preferably with a dough that has not undergone extensive fermentation (to rule out long fermentation as the cause of the blistering).

Peter

Offline November

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Re: Blistering in a Pizza Crust (Split Topic)
« Reply #62 on: January 06, 2009, 11:50:59 AM »
Peter,

I noticed he was talking about surface dryness, but at 80% hydration, it would take a while for even a dough surface to come to such a low moisture level, assuming a dry surface could be responsible.  No such experimentation is needed though.  I guess Tom has never seen a baked Play-Doh (or homemade dough variety) sculpture and applied inductive reasoning to determine that a dough with an initially low moisture level can bake with a perfectly smooth surface.  Sculptures and pottery made from clay and doughs all across the world and time would have this problem.  The mechanics of low-moisture (non-malleable) materials do not support such a hypothesis.  I would issue forth the following challenge to Tom: try blowing a bubble in a piece of leather.

- red.november

Offline November

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Re: Blistering in a Pizza Crust (Split Topic)
« Reply #63 on: January 06, 2009, 11:56:54 AM »
I thought that you would know what effects flow from dry doughs based on your prior work experience at Little Caesar's where, if my memory serves me, the dough was allowed to sit around uncovered for some time.

The problem with this situation, and the scenario one might setup to test the "dry surface" hypothesis, is that the other (more logical) factor of over-fermentation is in play at the same time.  The drier you allow the dough to get over time, the more fermented the dough becomes as well.  To solve this problem, make a dough without any yeast, let its surface dry out and see if you get blisters.

Online Pete-zza

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Re: Blistering in a Pizza Crust (Split Topic)
« Reply #64 on: January 06, 2009, 12:28:24 PM »
November,

That is a good idea. When I have a moment, I will give that a try. Can you suggest a period of time to allow the dough to "rest" before baking? Also, will the amylase enzymes try to convert starch to sugar during that time that might have an effect in some way on the blistering?

In the meantime, it looks like Tom has backed off on his explanation on the cause of blistering when he was asked for further elaboration. I have copied and pasted below his latest explanation, at http://thinktank.pmq.com/viewtopic.php?p=42217#42217:

I wish I could elaborate further on those little blisters (looks like a case of heat rash), but we have never set about to study them in depth. We see them on well fermented dough, as well as frozen dough. They also seem to be more prevelant on lower absorption doughs. For these reasons, we have a feeling that they are in some way, associated with oxidation of the dough skin, but we haven't consucted a study where we have attempted to control them.
Tom Lehmann/The Dough Doctor


Peter

Offline Pizza_Not_War

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Re: Blistering in a Pizza Crust (Split Topic)
« Reply #65 on: January 06, 2009, 12:49:10 PM »
Blisters

I have achieved that effect with long cold fermentation and direct spraying of water onto the loaf just before putting it into the oven and then again 1 - 2 more times in the first minutes of baking. This differs from what most tell you to do by spraying the oven or using a pan of water in the oven.



PNW

Offline November

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Re: Blistering in a Pizza Crust (Split Topic)
« Reply #66 on: January 06, 2009, 12:50:01 PM »
Peter,

Can you suggest a period of time to allow the dough to "rest" before baking? Also, will the amylase enzymes try to convert starch to sugar during that time that might have an effect in some way on the blistering?

I think the results are pretty predictable, but if you actually want to try it, just keep the dough around for a couple hours at room temperature.  Be sure to use the same techniques as if you were making a real pizza; such as lightly oiling the surface of the dough ball as it non-ferments, stretch the dough into shape the same way, and top it with minimal ingredients as a control to simulate true moisture level conditions surrounding the crust.

- red.november

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Re: Blistering in a Pizza Crust (Split Topic)
« Reply #67 on: January 06, 2009, 10:07:09 PM »
When the poster at PMQTT indicated that when he lightly oiled the dough with a canola oil spray before refrigerating or alternately brushing oil olive around the rims just before baking, the blisters were dramatically reduced. Tom Lehmann responded to that as follows (http://thinktank.pmq.com/viewtopic.php?p=42250#42250):

The oil application helps to seal the crust surface from the air, thus reducing the oxidation of the dough on the surface. This is why we feel that it may be caused by oxidation rather than drying of the dough. For some unknown reason to me, we have seen what we feel is a reduction in those blisters when higher dough absorption levels are used, or put another way, lowering the dough absorption seems to make the situation worse. The one next step that I would suggest is to increase the dough absorption by a minimun of 2% of the total flour weight: flour weight X 2 (press the "%" key) and read the amount of additional water to add in the display window. Keep in mind that you might need to do this more than once. Another thing is to look at your flour bag and read the ingredient label to see if the flour is bromated or not. If it does contain bromate, you might want to ask your supplier to get you a bag of the same flour, but without bromate to try. Bromate (potassium bromate) is an oxidant that is added to some flours by the mill to further strengthen the flour. In pizza production, we really don't need this extra strength, so you shouldn't see any ill affects to the dough, but by removing the bromate, you might also get rid of the blisters. Let me know what you find out.
Tom Lehmann/The Dough Doctor


Peter

Offline November

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Re: Blistering in a Pizza Crust (Split Topic)
« Reply #68 on: January 07, 2009, 10:04:44 PM »
Peter,

Reference Post: http://www.pizzamaking.com/forum/index.php/topic,637.msg58255.html#msg58255

In the above post you will notice that the crust is relatively smooth with almost no blistering.  Today I made two pizzas with the same dough, same procedures, same equipment (except for pan size), and same fermentation conditions, with just one material difference: twice as much yeast (0.6%).  Attached is an image of the resulting crust.  You can clearly see that the additional fermentation, or over-fermentation by some standards, has promoted a veritable gold-mine of blisters.  Neither dryness nor oxidization provide for a pocket of fluid that expands to fill a blister.

- red.november

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Re: Blistering in a Pizza Crust (Split Topic)
« Reply #69 on: January 21, 2009, 09:51:15 AM »
Following up on recent posts in this thread, I decided to conduct an experiment along the lines suggested by member November to see if I could induce blistering in a dough in which no yeast was included and where the surface of the dough was dry. For purposes of the experiment, I used a basic Lehmann NY style dough formulation, minus the yeast, as prepared as follows using the expanded dough calculating tool at http://www.pizzamaking.com/expanded_calculator.html:

Flour (100%):
Water (62%):
Salt (1.75%):
Vegetable (Soybean) Oil (1%):
Total (164.75%):
197.54 g  |  6.97 oz | 0.44 lbs
122.47 g  |  4.32 oz | 0.27 lbs
3.46 g | 0.12 oz | 0.01 lbs | 0.62 tsp | 0.21 tbsp
1.98 g | 0.07 oz | 0 lbs | 0.43 tsp | 0.14 tbsp
325.44 g | 11.48 oz | 0.72 lbs | TF = 0.1015
Note: The flour is unsifted Harvest King (“Better for Bread”) bread flour; the amount of dough is for one 12” pizza with a nominal thickness factor of 0.10 and a bowl residue compensation of 1.5%; the finished dough temperature was about 76 degrees F

The dough was prepared in the usual manner in my basic KitchenAid mixer with flat beater and C-hook attachments. Once the dough was done, it was shaped into a round ball, lightly coated with oil, placed in a covered plastic container, and subjected to a “nonfermentation” period of four hours at a room temperature of about 68 degrees F. I selected the 4-hour period as being sufficiently long to be able to also study the effects of enzymes in the flour on the production of natural sugars in the dough to contribute to crust coloration at the time of baking.

For the final hour of the 4-hour nonfermentation period, I removed the dough from its container, slightly flattened it into a disk, and let it sit, uncovered, so that the surface would dry out. At the expiration of the 4-hour nonfermentation period, the dough was shaped and stretched into a 12” skin. The dough was fairly extensible but it felt and behaved much as a yeasted dough with the same basic formulation. The skin was placed and dressed on a peel (using only diced mozzarella cheese and a basic pizza sauce), and baked on a pizza stone that had been placed on the lowermost oven rack position of my electric oven and preheated for an hour at around 500-525 degrees F. The bake time was around 6-7 minutes. To test the notion proffered by a member that coating the unbaked rim of the pizza with oil would induce blistering in the rim of the baked crust, I coated one half of the unbaked rim with vegetable oil (soybean oil, the same as used in the dough).

The photos below show the finished pizza. As can be seen, there was no blistering of the rim of the pizza, either the side without the oil or the side with the oil. Unless I did not properly conduct the experiment, it seems that a dry dough surface does not induce blistering in the finished rim and crust.

There were a couple of other interesting observations from the experiment. They don’t specifically relate to the blistering issue but I think they are worthy of mentioning nonetheless. The first is that there was some oven spring, albeit modest in this case. Since there was no yeast in the dough, it is clear that yeast, while perhaps serving some role in the oven spring process, as does the high heat of the pizza stone, is not necessary to get oven spring. The moisture content of the dough alone is sufficient to achieve it. This is a point that has been mentioned several times before, notably by member November and by Jeff Varasano. 

The second observation was the lack of crust coloration, especially at the baked rim of the pizza. I thought that perhaps sufficient enzyme activity would take place over a 4-hour period to yield sufficient natural sugars (residual sugar) to contribute to decent crust coloration at the time of baking. My best analysis is that the lack of normal crust coloration may have been due to one or more of the following: 1) insufficient sugar (simple sugars) created during the 4-hour nonfermentation period to induce crust coloration (that is, maybe four hours was not long enough); 2) the absence of enzymes present in yeast (including zymase and maltase) to convert certain complex sugars into simple sugars to be used for crust coloration purposes; 3) insufficient residual sugars to induce caramelization or browning because of the Maillard reaction (which requires simple sugars); and 4) the lack of the proper relationship of pH to residual sugars to achieve crust browning (due to the lack of yeast fermentation byproducts to achieve the proper pH.).

Peter


Offline JConk007

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Re: Blistering in a Pizza Crust (Split Topic)
« Reply #70 on: January 21, 2009, 09:58:02 AM »
Great stuff Peter !!
Read, Learn, Experiment, Learn, Read, Experiment, Learn, Read.........
Thanks
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Offline November

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Re: Blistering in a Pizza Crust (Split Topic)
« Reply #71 on: January 21, 2009, 10:45:29 AM »
Peter,

Since there was no yeast in the dough, it is clear that yeast, while perhaps serving some role in the oven spring process, as does the high heat of the pizza stone, is not necessary to get oven spring. The moisture content of the dough alone is sufficient to achieve it. This is a point that has been mentioned several times before, notably by member November and by Jeff Varasano.

Thanks.  This also adds to my discourse of old on how one can use a priori and scientific principles to make predictions concerning dough performance and crust characteristics instead of trying every permutation to achieve a desired product.  In other words, the "pizza making is an art versus science" debate really only exists where science isn't respected.  Sometimes it's fun to experiment, and sometimes it's necessary to experiment so that others may learn the process.  However, there's very little going on in pizza dough that would cause a macroscopic surprise if established biochemical and mechanical principles were first considered.

My best analysis is that the lack of normal crust coloration may have been due to one or more of the following: [...] 4) the lack of the proper relationship of pH to residual sugars to achieve crust browning (due to the lack of yeast fermentation byproducts to achieve the proper pH.).

I was tempted to suggest adding vinegar to the dough to compensate for the loss of organic acids caused by avoiding the yeast, but then I thought it should be a separate trial if you really wanted to see its effects.  A low pH will catalyze pyrolysis as already demonstrated here: http://www.pizzamaking.com/forum/index.php/topic,3985.msg41422.html#msg41422

- red.november
« Last Edit: January 21, 2009, 10:47:13 AM by November »

Offline November

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Re: Blistering in a Pizza Crust (Split Topic)
« Reply #72 on: January 21, 2009, 11:29:20 AM »
Peter,

By the way, you didn't answer what some people consider the most important question of all, "How did it taste?"

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Re: Blistering in a Pizza Crust (Split Topic)
« Reply #73 on: January 21, 2009, 12:00:07 PM »
Peter,

By the way, you didn't answer what some people consider the most important question of all, "How did it taste?"

- red.november

November,

The crust was soft in the middle with a bit of chew and crunchiness in the rim. The flavor of the crust itself was reminiscent of a salted matzoh cracker which, as you know, is an unleavened baked good made from only flour and water. I have read that you can make a "matzoh pizza" by putting a Kosher tomato sauce and grated cheese on a matzoh cracker and microwaving the "pizza" until the cheese melts. My version was a softer version of that.

I have always had a great deal of respect for yeast, as with any living organism, and especially the willingness of yeast to give up their lives for our purely personal, selfish, hedonistic pizza pleasure. However, after the latest pizza, my respect for yeast has increased immeasurably.

Peter

Offline November

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Re: Blistering in a Pizza Crust (Split Topic)
« Reply #74 on: January 21, 2009, 12:23:19 PM »
I have always had a great deal of respect for yeast, as with any living organism, and especially the willingness of yeast to give up their lives for our purely personal, selfish, hedonistic pizza pleasure. However, after the latest pizza, my respect for yeast has increased immeasurably.

I thought I had expressed my opinion on the flavor of yeast more explicitly, but I couldn't find where in a 10 second search.  I know that my use of ADY for the purpose of including more dead yeast cells is well known.

I will probably never use anything but ADY for all of my life. [...] The higher dead yeast count is the primary reason I use ADY.

Probably not as well known is the fact that I really like the flavor of yeast, whether it's dead or alive when being added to a dough.  Maybe you could try adding nutritional (dead) yeast and a little vinegar in another trial just for fun.  Here are some other related quotes from my past:

I always play it safe with the clean flavor of yeast only (intentionally anyway) fermentation.

Some people like the texture of biscuits, but also like the flavor of yeast.

Offline djones148

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Re: Blistering in a Pizza Crust (Split Topic)
« Reply #75 on: January 29, 2009, 02:27:07 AM »
Just to add more fuel to the fire, I read in a very technical baking book (one aimed at commercial bakers), that blistering is caused by condensation on the surface of the dough which creates spots of increased extensibility. Dough that is refrigerated gets condensation on it, as can dough that is steamed in the oven. Boiling before baking (bagels) would directly put water on the surface that would presumably create little droplets.

It might also be occuring in long fermented doughs due to the action of alpha-amylase enzymes. Damaged starch particles in flour have a very high capacity to absorb water, however as fermentation goes along, the amylase enzymes continue to hydrolyze the damaged starch (which is vulnerable to attack) into dextrins and the water is released. As more damaged starch gets broken down, the absorptive capacity of the dough is declining and water droplets could form on the surface.
« Last Edit: January 29, 2009, 02:29:05 AM by djones148 »

Offline David

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Re: Blistering in a Pizza Crust (Split Topic)
« Reply #76 on: February 03, 2009, 10:36:20 AM »
It's funny how I came to finding this blog,but it all started with Bill's new "Less is more" thread!I have never really taken any interest in the Science of "Molecular gastronomy",but the thread pushed me toward reading a little about it and discovering the following blog post.I believe the term maillard Reaction has been used more times by Peet-za than anyone else on the forum.....so this one's for you Peter ;D.The kicker for me in this apart from the Ph pointers, was the bi carb browning benefits for vegetables.Parts are a little above my comprehension,but I'm sure others can get something from it,
David

http://blog.khymos.org/2008/09/26/speeding-up-the-maillard-reaction/#more-399
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Re: Blistering in a Pizza Crust (Split Topic)
« Reply #77 on: February 03, 2009, 11:08:38 AM »
Thank you, David.

I always enjoy reading about the Maillard reaction. Recently, I did some Google searches on the subject, which took me to excerpts from many highly technical books on food science. I was also looking to see if there was anything of note on the blistering phenomenon. Needless to say, given the interest in this subject, I have also started to pay closer attention to the photos of members to see if I can find clues as to what causes the blistering.

Peter

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Re: Blistering in a Pizza Crust (Split Topic)
« Reply #78 on: November 29, 2009, 11:47:34 AM »
I had never had blistering in my dough before.  This past Tuesday, I had used some dough balls that had been frozen for a week.  Only 2 of the pizzas I made with this frozen dough blistered.  That is why I took a picture of the one rim.  I don't know what really caused this, but I had left these dough balls out to thaw and then reuse for a longer time than normal.
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Offline ThunderStik

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Re: Blistering in a Pizza Crust (Split Topic)
« Reply #79 on: November 30, 2009, 10:42:20 PM »
Pete, after reading this i went back and looked at past pics of my pies and whadda ya know, blisters. They are everwhere, i even went and looked at my leftovers from yesterday  and you guessed it they are all over the place.

I can post a pic if ya want.
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