San Francisco Sourdough Process

Title: Lactic and volatile (C2-C5) organic acids of San Francisco sourdough French bread

Cereal Chemistry 55(4): 461-468; Copyright 1978 The American Association of Cereal Chemists

Authors: A. M. Galal, J. A. Johnson, and E. Varriano-Marston

The Larraburu Company produces San Francisco sourdough French bread by the sponge-and-dough process. Each day, a piece of straight dough or starter sponge known as the "Mother" is saved and refrigerated to be used as a starter sponge the following day. This starter sponge is used to make more starter sponge as well as sponges for bread production. The starter sponge consists of 100 parts of clear flour (14% protein), approximately 50 parts of water, and 50 parts of the starter sponge. The ingredients are mixed and fermented for 9-10 hours at 80F.

The bread dough is made by mixing 100 parts flour, 12% protein, 60 parts of water, 15 parts of sponge, and 1.5-2% salt. The dough rests 1 hour and then is divided, molded, and deposited on canvas dusted with corn meal or rice flour. The dough is proofed for 4 hours at 105F (41C) and 96% relative humidity and baked at 420F (216C) for 40-50 min in a Perkins oven with direct injection of low pressure steam (5 psi). Oven shelves were covered with Carborundum.



From "Nature of the San Francisco Sour Dough French Bread Process, I. Mechanics of the Process" by Leo Kline, T. F. Sugihara, and Linda Bele McCready in Baker's Digest 44(2), p48-50.

Table I

Sour Dough Starter Sponge
100 parts previous sponge
100 parts flour (Hi-gluten)
46-52 parts water

Make up and hold 7-8 hrs. at 80F
Starting pH = 4.4 to 4.5
Final pH = 3.8 to 3.9

Table II

Sour Bread Dough Formulation
20 parts starter sponge (11% of total dough weight)
100 parts flour (regular patent)
60 parts water
2 parts salt
Make up – approx. 1 hr floor time – then proof 8 hr. 86F
Starting pH = 5.2 to 5.3
Final pH = 3.9 to 4.0

Preparation and Handling

The bread dough, as shown in Table II, is made up simply with the fully developed starter sponge, flour, water and salt. None of the other usual ingredients of white pan bread such as yeast, sugar, shortening, non-fat dry milk, monoglycerides, dough conditioners, oxidants, mold inhibitors, etc. are needed or used. The starter sponge is used at a level of approximately 9 to 15 percent of the final bread dough which, after make-up is allowed to relax for at least 30 minutes. Then it is scaled (divided), rounded and given an overhead proof of about 20 min at 90F, after which it is molded, placed on canvas dusted with rice flour and/or corn meal and allowed to proof about six to eight hours at 85 to 90F. This long proof time may be reduced somewhat by increasing the proportion of starter sponge or by lengthening the floor time before molding, but is generally essential for development of the acidity and the coarse grain typical of this bread as well as for volume.

The pH of the bread dough on make-up is about 5.3 and drops to about 3.9 when the long proof is completed, or roughly to the same point reached by the starter sponge itself.

Baking

Baking is carried out in a hearth (generally carborundum) oven for a relatively long time (45 to 55 minutes) at a relatively low temperature (375 - 390F). It is quite essential to slash or make cuts on the surface of the fully-proofed dough just before it is placed in the oven, otherwise the crust character will be wrinkled and generally unsatisfactory and the eating quality of the crust is probably the most essential part of this bread. Also an absolute requisite to achieving the desired crust character is the use of a very wet oven, particularly the first part of the baking cycle and continued until the crust attains a light tan color. Generally this is achieved by saturating the oven with low pressure steam.