What causes these types of bubbles?!

[hotsawce]

Tom,

I was wondering if you could tell me what causes these types of bubbles. They are flat, wide, and pretty crispy. I've never seen them on a pizza other than Lucali.

I know the pie is rolled out with a rolling pin and bakes around 700 degrees but it's doll very unique.

[HansB]

Lou, that looks like it puffs like pita bread. Maybe from rolling thin?

[hotsawce]

Hans,

I used to think the dough was very thin, but I don't think it's as thin as I originally thought. Here is an excellent video of the pie being made...even in the title picture the dough doesn't look all that thin on the edge...

[HansB]

That looks great. Now I'm hungry again. 

Looking forward to what Tom thinks about it.

[The Dough Doctor]

Pizza dough when rolled thin and baked at 700 to 800F is commonly called "pita" .
This is also how we achieve a cracker type crust characteristic too. In fact it is how crackers are made (but usually with some laminating). Usually the skin is well docked to control the size of the bubbles. You might see a few of them in the area under the toppings but they are most prevalent around the un-topped edge of the pizza where there is no sauce or toppings to control the bubbling.
Tom Lehmann/The Dough Doctor

[hotsawce]

Tom,

That's interesting. I've tried to roll dough thin in my home oven but I never got those thin flat bubbles...so you think it's largely a heat and thickness thing, huh?

There was one time I got those bubbles at a wood fired pizzeria I worked at a little while ago. We stretched the dough (by hand) relatively thin and evenly to the edge (no cornicione.) The dough was very salt heavy, so it stayed dense most of the time. One day, the dough felt more slack than normal (we used to have to struggle to open the dough because of all of the salt. I also think the pies baked up soft and not crispy because of all the salt.) When baked, even at 800 degrees, we got those thin bubbles on the outside of the rim and it was much more crispy than normal...at the same temperature we always baked at. AWESOME pizza. I couldn't figure out what caused it...but I think the dough guys may have forgotten some salt in that batch...

Tom, do you think salt level plays a part in those bubbles and that texture? Could less salt lead to a crispier crust?

Edit: Also, I had to find a pita video after you mentioned it. The edges look EXACTLY like lucali in the initial stage of the bake. I assume the toppings on the pizza weigh down the center so it doesn't puff up, but you still get those edge bubbles. Now to determine thickness factor...

[The Dough Doctor]

We have never seen any direct relationship between the salt level and crust crispiness.
Tom Lehmann/The Dough Doctor

[la_marziana]

wow, that's interesting! this may sound off topic at first, but i remember when i first started making pita, i had trouble with them poofing consistently(like, into one big balloon, instead of multiple bubbles with flat spots). i found out that using two grocery store style generic bamboo skewers on each side of the dough discs, while them rolling flat as evenly as possible (and giving them a little rest before baking) will almost always result in even balloon style poofing for me- even in an oven set to 450F, but much more rapidly if the temperatures are higher. so, thinking back on that these two things were the only thing i did differently to when it unevenly poofed, it makes me think that it has something to do with even thickness where the bubbles are, and then an unevenness where it doesn't poof/where the toppings are and of course enough heat to create the steam...? i have never seen this on a pizza, but when there's a "kink" in the pita disc, it will not poof in that spot, at least not for me. i have no idea if this is helpful at all😬

[hotsawce]

That was the next topic I was going to hit on...I've made pita that doesn't bake like the video above. Like you said, it "poofs" all at once into one big balloon.

But Lucali essentially does the process you mentioned. The dough balls are rolled out with a rolling pin a little bit ahead of time and left on the make table so they can be grabbed immediately when ready to bake. I wonder...

Sounds like there's a certain set of factors that leads to those types of bubbles...that bake above is exactly how Lucali looks when it starts baking up.

wow, that's interesting! this may sound off topic at first, but i remember when i first started making pita, i had trouble with them poofing consistently(like, into one big balloon, instead of multiple bubbles with flat spots). i found out that using two grocery store style generic bamboo skewers on each side of the dough discs, while them rolling flat as evenly as possible (and giving them a little rest before baking) will almost always result in even balloon style poofing for me- even in an oven set to 450F, but much more rapidly if the temperatures are higher. so, thinking back on that these two things were the only thing i did differently to when it unevenly poofed, it makes me think that it has something to do with even thickness where the bubbles are, and then an unevenness where it doesn't poof/where the toppings are and of course enough heat to create the steam...? i have never seen this on a pizza, but when there's a "kink" in the pita disc, it will not poof in that spot, at least not for me. i have no idea if this is helpful at all😬

[hotsawce]

Tom,

Do you have any idea why the pita bread in the above video kind of puffs irregularly around the crust, while some pita just puffs unevenly into one giant inflated balloon?

I think this will help me get to where I want to be with this style of pizza. It all looks like a pretty typical, 60% hydration dough of just flour, water, salt, and yeast rolled relatively thin and baked at moderately high temps.

[invertedisdead]

Hans,

I used to think the dough was very thin, but I don't think it's as thin as I originally thought. Here is an excellent video of the pie being made...even in the title picture the dough doesn't look all that thin on the edge...

Thanks for posting this clip, I've watched it like 3 times now. The way they build the pizzas is really cool, using the mandolin. What's in the sauce? Whole peeled? Basil?

[hotsawce]

Could anyone recommend a thickness factor for this style that might work for his pita effect?

Also, another question for Tom regarding the salt. Could an excess of salt lead to the crust being overly dense? The few pizzas I baked that actually had the bubbles we "think" the salt was forgotten in the dough. Typically, the dough for this pizza was always very dense, very salty, never rose in the oven,  was also  to open, and was very difficult to get crispy. The pies that baked up with those pita bubbles felt like the same hydration, but it opened effortlessly compared to the normal dough (hand stretched thin on the edges.) It didn't spring back, either. It was crispy, and I could bake on the same spot in the wood fired oven for the following pie and that baked up crispy as well.

This was all during the same hour. One tray was the dough that baked up perfectly and when we got into the tray of new dough it was back to the same old same old.

Just trying to figure out what night have caused the change in rise and crispness, because it was very Lucali-like.

[hotsawce]

Also, why would Lucali not have any black leopard spotting baked at those temps? It's evenly brown and almost grey...other pies baked that hot tend to have the spots.

And, why would a Lucali pie (or the pie I made once) puff up with bubbles like that (whether rolled thin or hand stretched super thin) but the new haven pies don't get those bubbles and tend to stay pretty flat and dense?

[The Dough Doctor]

Pita (not actually a "bread") comes in two basic flavors, pocket type and non-pocket type sometimes referred to as "Greek" pita. All pitas are best when allowed to proof for 15 to 20-minutes after forming. The pocket type pitas that most of us are familiar with are best baked at temperatures of 800F and above which results in a large single pocket characterized by a darker brown spot about 2-inches in diameter on the side in contact with the deck surface. Baking times are typically around 30-seconds +/- 5 seconds. The non-pocketing pitas are made in the same manner except that they are baked at a much lower temperature, typically 450 to 500F. When baked in this manner the water is not turned to vapor as quickly so a large pocket is not quickly formed, but instead many smaller pockets are formed which if given sufficient time in the oven will usually form into a single large pocket but occasionally the pocket will not be complete leaving some of the pita without a pocket (partial pocket formation). One of the main issues with making pitas at low baking temperatures is that proofing time becomes critical, if it is too short the resulting pita will have a pocket that is very thin on one side and thicker on the other side which creates a problem if you're using the pita to make a filled sandwich as the thin side easily tears or disintegrates when brought into contact with a moist/wet filling.
Tom Lehmann/The Dough Doctor

[hotsawce]

So this is what happens when you take Rubirosa's thin dough and bake it in a wood fired oven. They did San Gennaro Feast a couple years back and a few pictures exist. Note the bubbles on the rim. Good looking stuff.

https://www.flickr.com/photos/lauraofthevalley/15964105917

[The Dough Doctor]

The application of just some of the sauce during baking will significantly reduce bubble formation in a thin crust as it prevents the dough from getting hot enough to vaporize water into steam which is responsible for the pocket which is formed in a real pita. From what I see in the photograph it appears that the dough as in the process of pocketing but the sauce/toppings prevented much of this from occurring, the edges were locked in place (thus preventing any more pocket or bubble formation) by the oven heat which bakes the edges faster than any other part of the skin since it is baking from three dimensions (top, bottom and sides) as opposed to the rest of the skin which is only receiving heat/baking from the bottom.
We have made Greek style pita pretty successfully by placing the skin in the oven and allowing it to just begin to bubble and then turning it over which locks in the bubble formation and effectively controls pocket formation.
Tom Lehmann/The Dough Doctor

[hotsawce]

This could explain why coal oven pies like Patsy's, Juliana's, and and John's don't have any rise in the edge of the crust. They are all paper thin and cooked in about 3 minutes, but topped to the edge. I would imagine this would prevent bubble formation.

Interestingly, the pizza in that photo with the largest bubbling on the crust is the white pie...the rest have sauce to the edge. I've noticed more bubbling on white pies for some reason...maybe because it's relatively dry until the cheese starts to melt.

The application of just some of the sauce during baking will significantly reduce bubble formation in a thin crust as it prevents the dough from getting hot enough to vaporize water into steam which is responsible for the pocket which is formed in a real pita. From what I see in the photograph it appears that the dough as in the process of pocketing but the sauce/toppings prevented much of this from occurring, the edges were locked in place (thus preventing any more pocket or bubble formation) by the oven heat which bakes the edges faster than any other part of the skin since it is baking from three dimensions (top, bottom and sides) as opposed to the rest of the skin which is only receiving heat/baking from the bottom.
We have made Greek style pita pretty successfully by placing the skin in the oven and allowing it to just begin to bubble and then turning it over which locks in the bubble formation and effectively controls pocket formation.
Tom Lehmann/The Dough Doctor

[TXCraig1]

This could explain why coal oven pies like Patsy's, Juliana's, and and John's don't have any rise in the edge of the crust. They are all paper thin and cooked in about 3 minutes, but topped to the edge. I would imagine this would prevent bubble formation.

The beat the [email protected] out of the rim when opening as well.

[TXCraig1]

The application of just some of the sauce during baking will significantly reduce bubble formation in a thin crust as it prevents the dough from getting hot enough to vaporize water into steam which is responsible for the pocket which is formed in a real pita.

I think the weight of the sauce/toppings also plays a role in preventing the formation of large bubbles. Look at a loaf of poorly formed bread. Where do you typically find large voids? Near the top where there is not much weight and strength to the dough.

I think dough strength plays an important role - not just in the rheological sense - but perhaps more importantly in the physical sense that a thicker dough is stronger than a thinner dough. Once a bubble forms in a very thin dough, there is very little strength to keep it from expanding, tearing apart the nearby bubbles into one giant bubble. I also suspect that a rolling pin or aggressive pressing of the disk is important as it badly damages the bubble structure in the dough. My guess is that this leads to uneven expansion. The less even the expansion, the more you will have areas of excessive pressure that will result in large bubbles.

[hotsawce]

Interesting. I've gotten bubbles on the rim like that from hand stretching thin on the edge. Why would a rolling pin be any more gentle than how they stretch at Patsy's or John's?

I think you might be on to something with dough strength. Aside from thinness of the rim, the pies I did hand stretch that bubbled wildly on the edge in that way...the dough felt much more slack than it normally had. In essence, not a strong dough. We think the salt was forgotten in the dough that day, or maybe it was an old tray, but it was extremely slack and was the only time it had bubbled up like that.

I think the weight of the sauce/toppings also plays a role in preventing the formation of large bubbles. Look at a loaf of poorly formed bread. Where do you typically find large voids? Near the top where there is not much weight and strength to the dough.

I think dough strength plays an important role - not just in the rheological sense - but perhaps more importantly in the physical sense that a thicker dough is stronger than a thinner dough. Once a bubble forms in a very thin dough, there is very little strength to keep it from expanding, tearing apart the nearby bubbles into one giant bubble. I also suspect that a rolling pin or aggressive pressing of the disk is important as it badly damages the bubble structure in the dough. My guess is that this leads to uneven expansion. The less even the expansion, the more you will have areas of excessive pressure that will result in large bubbles.