Re: Blistering in a Pizza Crust (Split Topic)

[Pete-zza]

Note: Split from Randy's Harvest King Flour thread at http://www.pizzamaking.com/forum/index.php/topic,4284.msg35772.html#msg35772

To member giotto,

The photo you posted of your pizza at the abovereferenced thread is a fine looking pie. I have reposted the photo below.

Looking at the photo, it looks like your pizza rim has a lot of blistering. Or maybe it is sesame seeds or something like that. Members often ask how to get a lot of blistering intentionally and I have not been able to tell them how to do it. I know that you don't let your dough warm up beyond about 1/2 hour before using, and also that you prefer to pre-bake your dough skin before finishing. Do you think that either, or possibly both, of those events is responsible for what appears to be blistering? Or maybe it's something else.

Peter

[giotto]

Hey Pete-zza:

Thanks. It has a lot to do with water. Artisan breads often have blistering. It's a deady giveaway that the baker ferments his dough in the refrigerator. I once had a baker tell me he didn't ferment his breads in the refrigerator. But blistering was evident. I knew he used a preferment, and he then agreed that his preferment was refrigerated.

Artisan breads also use steam when they are made. My oven smokes with steam because like you said, my dough is a bit colder than most from the refrigerator. Sometimes, I even spray water in my oven when I put the pizza in the oven. I do this with bread as well. For the pizza above, I didn't spray though.

With my Pizza Hut version below (this one was a predecessor to the one under the Pizza Hut track), the water gets trapped at the bottom and blisters form big ol' holes like their pizza (Pizza Huts that I spoke to refrigerate overnight). When I make bread, I use parchment paper and soak the bottom-- same result.

Hope this helps.

 

[Pete-zza]

giotto,

Thanks.

Recently, after failing to intentionally create a blistered crust (cold, underfermented, high hydration doughs, high oven temperature, etc.), I did some online research on artisan bread doughs because it seemed to me that I often saw artisan breads that had highly blistered crusts. In some cases, the blistering was considered a defect to be eliminated. Steam was listed as one of the possible causes, along with overfermentation. I have found that I am more likely to get blistering when the dough is in a late stage of fermentation, shortly before heading south. I may try steaming the oven, as I do when I make bread.

Peter

[November]

I only get blistering when I let the dough go too long.  I don't think hydration makes much of a difference.  I've been up and down the entire spectrum of hydration and it's never influenced crust appearance in that way.  I believe it is a byproduct of dead yeast colonies where in the final stages of fermentation before death, the yeast pump out incredible amounts of waste.

- red.november

[dinks]

PETER:
  Good sunday afternoon to you. By now you should be back from Sunday services in time to read my info on pizza crust blistering.

   COMES NOW:

Simply put, blistering is caused by gas escaping from the crust while the dough mass is in the refridgerator being in retard mode.

  You see my friend, gas is lost more quickly in cool dough because cooling increases the solubility of carbon dioxide in water.  Upon baking the pie, the water that has accumulated in the small cells that are remaining form the blisters.
  Some customers think having those are sexy.  I do not pay any attention to those things. My moment with you has come to an end my learned friend. I hope this helps. I look forward to reading your postings from time to time. Good day sir.

  ~SMARTY PANTZ.

[November]

dinks,

I'm not sure how you arrived at that conclusion.  The solubility of CO2 in water does indeed increase inversely with temperature, but with that being the case, less gas will escape during cold fermentation, not more.  Those blisters are in fact filled with water, alcohol, and liquid waste products from the yeast; so beginning with your explanation of what happens in the oven, you are correct, but cold fermentation doesn't have anything to do with it.  I've acquired those blisters on a very predictable basis, and I rarely cold ferment my dough.

- red.november

[DNA Dan]

I've acquired those blisters on a very predictable basis, and I rarely cold ferment my dough.

What part of your process do you think is most responsible for the blistering? Or is it not that simple?

I have been doing a 2 hour proof, overnight ferment in the cooler, then 1 hour proof in bags and I NEVER see blistering like that. I have also tried cooking it right out of the cooler, still no blistering. 

The pizza in the photo, is that pickles on the top? Green tomatoes?

And finally, RANDY!! That recipe rocks! Thank you so much for sharing. I figured it must be something special because not a lot of members can say they have a recipe named after them on these boards.

[November]

What part of your process do you think is most responsible for the blistering?

I think there may be at least two roads one can take to reach the same destination on this, but for me, the road is exactly as I mentioned: over-fermentation.  My doughs rise at exactly 68 F on the bench (declining from 86 F from the start), covered with oil, and then covered with a container (upside-down).  With the amount of yeast I currently use, I get population overruns if I leave the dough out for more than 6 hours and the colonies near the surface where the oil has ben absorbed into the skin die out sooner as a result of habitation strain.  As an FYI, habitation/environmental strain can also happen because the surface of the dough is too cold; so this may be the source of the cold fermentation theory, but if kept properly, cold fermentation should not be a cause for blistering.

- red.november

[giotto]

Personally, since bubbles have not impacted taste, it's not really important to me. But for the sake of accuracy on my picture above, the dough was definitely not anywhere near at the end of its fermentation. I produce bubbles with short fermentation times, zero growth in the refrigerator and plenty of spring in the oven with a flour that is made for, and has shown a propensity to sustain, many more days of fermentation (as discussed in the link, http://home.comcast.net/~keck-foundation1/pizza-crust-color.html, that's embedded with the writeup for the picture). I've found the same to be true with bakeries that produce great color, spring, bubbles, etc., with their bagels and breads, using short fermentation times, no use of a preferment, and with flours that also can sustain longer fermentation times.

I have to admit, I try lots of variations in toppings; but not quite pickles (although I used cucumber before). My "sauce" was: fresh tomatoes cut up, zucchini (the green stuff), red onion, green olives and a little basalmic vinegar with salt & herbs.

EDIT by Pete-zza (1/22/15): I believe that the following Wayback Machine link is the same or equivalent to the inoperative link above: http://web.archive.org/web/20120209002605/http://home.comcast.net/~keck-foundation1/pizza-crust-color.html

[November]

zero growth in the refrigerator

If you are getting zero growth in the refrigerator, the temperature is low enough to completely inactivate the yeast near the surface of your dough.  This is one of the several reasons I rarely cold ferment my dough: my refrigerator is too cold.  I typically get zero growth and the yeast near the surface dies.  Of course the main mass of the dough always springs back after bringing it up to room temperature again, but the damage to the surface is already done.

- red.november

[November]

giotto,

Turn your dough ball inside-out when you form the crust to see if you still get the blisters.

[giotto]

I get zero growth initially because I use so little yeast or because I use cold water. Over time, the dough can grow. Yeast does NOT die at low temps-- it becomes inactive as you suggest. My dough will not spring if I use too little yeast, or when I kill the yeast... I've done this before. My refrigerator is not that cold. My dough is not at freezing temps where crystals or other problems will occur.

[Randy]

I am not sure what you are talking about when you write of blisters

[giotto]

Randy:

It's the stuff you often see on bagels and breads at various bakeries; The outer crust looks like it is blistering. We seem to get them under different circumstances. It may be because moisture or dead yeast sitting on the surface, which apparently can occur under different circumstances. My focus in the past has been more on color for presentation and taste.

[November]

I get zero growth initially because I use so little yeast or because I use cold water. Over time, the dough can grow.

Then that wouldn't be zero growth, would it?  All yeast starts at zero fermentation initially.

Yeast does NOT die at low temps-- it becomes inactive as you suggest.

Inactive generally means not able to continue fermentation, as in dead.  You're thinking of the term dormant.  It is quite possible for yeast to die at refrigerator temperatures given extenuating circumstances.  The simple shock of the temperature dropping can kill as much 1-3% of the yeast, regardless of how low the temperature gets.

I would say the blistering is a result of capillary action, but I haven't observed any pattern related to that theory.

Randy,

Where the white spots appear on the crust's rim.  What's known for sure is that these are vacuoles of liquid that prevent browning at the same rate as the rest of the rim, and at the same time swell due to liquid expansion from heat.

- red.november

[giotto]

I said zero growth because when I removed the dough, it was zero growth. This was not to suggest that it would never grow because I have witnessed otherwise with much longer fermentation times. And as I suggested, I am not at extenuating circumstances with low temp or shocking situations. And as I mentioned, I have yet to see spring with little use of yeast that dies.

[November]

I said zero growth because when I removed the dough, it was zero growth. I didn't say that it would never grow.

Did it, or did it not grow while in the refrigerator?

[giotto]

Please note the words... "it can grow" as used in the one quote you referred to vs. "when I removed the dough it was zero growth." So it did not grow on this last short fermentation, at least not noticeably where my eyes noted it. I merely delayed the fermentation period. Hence, if I had let the dough go longer, I would suspect that it would have grown over longer periods of time since yeast can still multiply at cooler temps... Just not to the degree at warmer temps.

[November]

giotto,

I noted both.  That's the reason I asked for clarification.  All I wanted to know is if the dough expanded (grew) while in the refrigerator.  For the purposes of my explanation, I wasn't concerned with growth anywhere else, and here's why:  If there is zero fermentation while in the refrigerator, then there isn't an internal source of heat to keep the yeast at the surface from experiencing inordinate amount of thermal shock.  Zero growth means zero thermal byproduct from fermentation.  If you're getting at least some growth in the refrigerator, the chances of surface yeast survival increase.

Ethanol also increases the entropy of activation, so if enough ethanol has a chance to build up around the surface yeast (via capillary action), it only takes temperatures as low as 50-60 F to deactivate the yeast.  This is why, in my opinion, if someone wants to cold ferment their dough, they should have sufficient oil in the dough to impede capillary action.  Also, without an oil layer on the dough itself, evaporation will occur and cool the surface even more as a result.

- red.november

[giotto]

I used 1 TBL oil per 10 oz flour. I split them after making the dough, with plenty of oil on the outside of one dough, and minimal on the other (I was making 2 different styles of crust). Both got bubbles.  Regarding zero fermentation, the wording suggests that my eyes noted insignificant growth; but it's difficult to say if there was zero fermentation actually occurring chemically. I suspect the fermentation is significantly slowed down.

The weird thing is that Pete-zza and others have mentioned extreme cold conditions, and have not been able to achieve bubbles. I'm curious as to what their eyes noticed in growth beforehand.