San Francisco Sourdough Bread: Was the secret worth revealing?
San Francisco Sour Dough French Bread
Kline, Sugihara and McCready
(The Bakers Digest, April, 1970)
In their 1970 Bakers Digest articles, Kline, Sugihara and McCready first deliniated the microbiology of San Francisco Sourdough bread. Their discovery of the special relationship between the dominant yeast – S. exeguna – and a unique species of Lactobacillus provided understanding of the special flavor of San Francisco sourdough and the stability of the sourdough cultures over time.
In the first of their articles, they also described the process San Francisco bakeries used to maintain their starters and make their breads. They describe the process as if all of the bakeries used the same process without actually stating this was the case. Regardless, the process they describe is significantly different in several respects from those found in any of the currently popular baking books in my collection. Because of that, and because I'm curious about whether the process they described can be successfully replicated in my own kitchen and produce bread like that of the traditional San Francisco sourdough breads with which I'm familial, I made a couple of loaves following their procedures.
The formulas and procedures described by Kline, et al. in the articles cited are as follows:
Ferment for 7-8 hours at 80º F
In the bakery, fed every 8 hours
Can feed less often by fermenting for 6 hours and retarding at 50-55ºF or fermenting 3-4 hours and retarding for longer times with refreshments 3-4 times per week, rather than 3 times per day.
Mix ingredients (No mix method or time is given.)
Rest for 30 minutes at room temperature.
Divide and pre-shape.
Proof for 1 hour at 90ºF
Proof for 6-8 hours at 85-90º F.
Score loaves and Bake with lots of steam for the first half of the bake at 375-390ºF for 45-55 minutes.
To make 2 kg of dough, I proceeded as follows:
1. I built the firm starter for the sponge with two elaborations, starting with my firm stored starter.
2. The sponge was mixed and fermented at 80º F for 10 hours.
Note: Accounting for the flour and water in the sponge, the actual final dough hydration was 58.9%.
All the dough ingredients except the salt were mixed and allowed to rest, covered, at room temperature for one hour.
The salt was sprinkled over the dough and mixed in a Bosch Universal Plus mixer at First (lowest) speed for 1-2 minutes, then at Second speed for 5 minutes.
The dough was then divided into two 1 kg pieces, pre-shaped as rounds and proofed at 90º F for 1 hour. (I placed the pieces on a bakers' linen-covered 1/4 sheet pan in a Brød & Taylor Folding Proofer.)
The pieces were than shaped tightly as boules, transferred to floured bannetons and placed in plastic bags.
The loaves were then proofed in the Folding Proofer at 85º F for 6 hours.
45 minutes before baking, the oven was pre-heated to 450º F/convection with a baking stone on the middle shelf and a cast iron skillet filled with lava rocks on the bottom shelf.
The loaves were dusted with semolina, transferred to a peel, scored and loaded on the baking stone. A perforated pie tin filled with ice cubes was placed on the lava rocks. The oven was turned town to 380º F/conventional bake.
After 23 minutes, the skillet was removed from the oven. The oven setting was changed to 360º F/convection bake, and the loaves were baked for another 22 minutes.
The oven was turned off, but the loaves were left on the baking stone, with the oven door ajar, for another 15 minutes.
The loaves were then cooled on a rack before slicing.
This is a low-hydration dough. After mixing, it was very smooth and barely tacky in consistency. It was still very dry and firm before the final shaping. After the six hours final proofing, the dough was very soft and puffy. I was afraid it was over-proofed and would deflate when scored or, at least, have poor oven spring and bloom. However, It took the scoring well and had good oven spring and bloom.
The baking temperature was lower than I usually employ for lean dough hearth loaves, and the crust color was thus lighter than most of my bakes. The crust color was quite characteristic of the San Francisco Sourdough breads I remember from the 1960's and 1970's. The loaf profile also was typical – a rather flat loaf.
The aroma of the vented oven air was remarkably sour during the final 10-15 minutes of the bake. The bread, once baked, cooled and sliced, revealed a very even crumb. The crust was somewhat crunchy but more chewy. The flavor was minimally sour and had little complexity or sweetness to it. All in all, a handsome loaf with undistinguished eating quality.
I expect I could tweak more sourness out of this dough by retarding the loaves overnight, but I don't particularly feel inclined to experiment further when there are so many other breads that are so much better.
Comments regarding the process described would be very welcome. I am curious regarding the disparity between the San Francisco Sourdough's I have had, supposedly produced by this method, and what I baked at home. Any thoughts?