Yesterday, I decided to look at the photos in the posts of the emergency dough recipes as set forth in the collection of emergency dough recipes at
http://www.pizzamaking.com/forum/index.php?topic=8297.msg71576#msg71576. What I was looking for were emergency doughs that, when made into pizzas, had blistering on the rims of pizzas. To qualify as an "emergency" dough for definitional purposes, I meant a dough that was made at room temperature and ready to be used in about four hours.
Although some of the styles do not have distinct rims but are rather on the flat side, such as the Chicago thin and cracker style pizzas, to be thorough in my study I decided to look at all of the styles anyway except for the Sicilian style pizzas that, because they are baked in pans, do not have a distinct rim as are common, for example, with the NY, Neapolitan and American style pizzas. I even looked at the Chicago deep-dish pizzas even though they do not have rims. As it turned out, those pizzas did not exhibit blistering anywhere on the crusts that I could see. It may well be that the high fat/oil quantities used in such pizzas inhibits any kind of blistering, especially given the short fermentation windows.
My study of the photos did not find any emergency dough that produced a crust with a blistered rim. In a few cases I saw blistering of rims but, upon further analysis, I found that they were not made from emergency doughs as I defined them but rather from doughs that had been fermented for more than four hours, usually considerably longer, even days. The posts for such doughs were usually entered to make a point or for a member to suggest improvements. For the most part, the rims of the pizzas I looked at tended to be quite smooth with few surface irregularities other than some occasional bubbling or charring. And some crusts were lighter in color than others. But no blistering.
I can't say that I was surprised not to find an emergency dough (as I defined it) that yielded a crust with a blistered rim. Even though emergency doughs use a lot of yeast (more than normal) and water that is quite a bit warmer than normal, such doughs rarely approach a condition of exhaustion from a fermentation standpoint where they are on their last legs. One can usually punch the dough balls down, sometimes even more than once, and they will start their rise again. They also have little opportunity to yield acids in sufficient quantity to affect the finished crusts because of the short fermentation window.
There may well be doughs that were fermented longer than four hours but less than the roughly three days of cold fermentation that I mentioned in one of my earlier posts, so there is that gap where doughs might exist that did yield crusts with blistered rims. As one example I found this morning, see
http://www.pizzamaking.com/forum/index.php?topic=14486.msg144461#msg144461. In that example, the fermentation was two days (cold fermentation) but the pizza was baked part of the time under the broiler. Whether that affected blistering I have no idea. Also, no oil was brushed on the rim of the skin.
Peter