An unplanned experiment: Differences in oven spring and bloom.
Above are pictured three loaves of San Francisco Sourdough made from the recipe in Peter Reinhart's "Crust and Crumb." They each turned out with subtle differences that are instructive regarding the variables that affect the appearance of our loaves. I thought it might be useful to describe these differences and what produced them.
I'm not going to describe the formula or method, because these were according to the recipe and were identical for all 3 boules. They were proofed in identical coiled reed brotformen. The two loaves on the right were baked together. The one on the left was baked 45 minutes later, and was left in the refrigerator, where all had been cold retarded overnight, 45 minutes longer than the other two. As you can see, they were scored with the same checkerboard pattern. Both bakes started in a 500F oven. The temperature was lowered to 450F when the loaves had been loaded. They baked for 30 minutes then were left in the oven for another 10 minutes with the oven turned off and the door ajar.
What were the differences in my procedures, then?
For the first bake (the two loaves on the right): 5 minutes before loading the first loaf (the one in the middle). a handful of ice cubes were put in a pre-heated metal loaf pan on the lowest shelf. Then, I dumped the boule on a peel, scored it and loaded it. The oven door was closed. I scored the second loaf (the one on the far right) and loaded it. I then poured a cup of boiling water into a pre-heated cast iron skillet on the bottom shelf and closed the door. The loaf pan and the skillet were removed after 10 minutes.
For the second bake, the loaf on the far left was scored and spritzed with water, loaded and then covered with a stainless steel bowl. The bowl was removed after 10 minutes.
What were the differences in outcome?
Comparing the two loaves baked together, the first one loaded had better oven spring and better bloom. I think it got the benefit of a slightly higher initial oven temperature. The second loaf was loaded within 2-3 minutes of the first. I have seen this difference between 2 loaves loaded sequentially in this manner repeatedly. I think the differences are "real."
The third loaf and the first (the one on the far left and the middle one) had about the same oven spring and bloom. If anything, the loaf in the middle had more. They were both, of course, the "first" loaf loaded. However, the one baked under a bowl for 10 minutes had a much shinier crust due, I think, to dissolved and gelatinized starch on the surface. The difference "in person" was more dramatic than what I see in the photo. This shininess is an effect I've seen only with breads baked covered. The longer the loaf is covered, the stronger the effect.
These differences may be of little significance. All three boules are quite satisfactory. But the differences do elucidate the effects of minor changes in temperature and humidification and might answer questions other have about how to achieve desired improvements in their breads.
FYI, we had part of the loaf on the left with dinner (Onion soup and Dungeness crab cakes with an Anderson Valley Sauvignon Blanc). The bread had a crunchy crust, typical chewy crumb and lovely complex soudough flavor. This is still a fabulous version of SF Sourdough.
Any comments about the observed differences would be welcome.