Sourdough was man's first leavened bread. Depictions of wheat grinding and bread baking can be found in Egyptian artwork dating to 2400 B.C.E. in the Temple of Ti in Giza. According to Ed Wood, a scholar and researcher with Sourdoughs International, Cascade, Idaho, the sourdough culture that leavened early Egyptian bread is still viable today.

Naturally occurring yeast strains and lactic acid bacteria (LAB), are the building blocks of the sourdough fermentation process. Every geographic area has viable sourdough microorganisms indigenous to the region and the bakeries that use them. “Starters give the baker the advantage of working with bacteria and yeast that are native to their area. The cultures are the baker's ‘terroir,’” says Aaron Brown, CB, C.H.E., baking and pastry instructor at the Culinary Institute of America, Greystone, N.Y. Starters produce lactic acid and sometimes carbon dioxide, acetic acid and alcohol, depending on the yeast, LAB species and the substrate. The combination of these factors is what makes each strain distinctive.

Brown typically has five starter cultures in process at the school: the original “Greystone” culture, rye, whole wheat, durum wheat and a “super starter,” which is unique to each class. Dough can be made from any or a combination of these to enhance the flavor and quality of the bread. A combination of the rye and the whole wheat cultures, for instance, brings a richer, deeper flavor to a baguette than using the wheat culture alone.

Rebirth of the starter

Wood has seen interest rise in the development of sourdough breads in commercial bakeries, “a rebirth,” he claims. Research from Puratos USA, Cherry Hill, N.J., supports the claim in a report that indicates 90 percent of consumers say they purchase bread based on flavor. The use of a sourdough, or levain, can greatly improve the flavor and uniqueness of a bread product, thus giving consumers what they want: flavorful, unique bread with good eating and keeping qualities.

“Cultures for baking are stable preparations of selected LAB and yeast, used to control a single-step levain fermentation and make the same quality every time,” says Thomas Serouart, development manager, Lallemand Baking Solutions, Montréal. “They help improve shelf life, enhance flavor through the production of lactic acid, acetic acid and fermentation aromas, while reducing the bran bitterness. They improve the crumb by providing elasticity, improve dough machinability, reduce dough mixing time and increase water absorption. That's a whole lot of performance for one natural ingredient.”

In both commercial operations and smaller artisan bakeries, sourdough bread making is a much different process than bread making using commercial yeast. Wild yeast strains have less proofing power than commercial yeast, but are more active at lower temperatures and require fermentation temperatures around 60°F to 65°F rather than 75°F to 90°F for commercial yeast.

LAB ferment quicker at higher temperatures than wild yeast strains. At temperatures of 75°F to 90°F, a culture made of wild yeast and LAB will generate more lactic acid production, thus providing more acidity or “sour” than at lower temperatures. Bakers can manipulate the proofing temperatures to influence the flavor, acidity and crumb of the finished product.

It's easy for small bakeries to maintain the integrity of each distinct culture of a spontaneous starter, given the relatively wide range of variation they are likely to accept. Industrial bakers and higher volume artisan bakers, though, require the guaranteed reproducible quality and activity that industrial starter cultures provide. Bakers must keep the culture from getting infected by pathogenic bacteria and molds in the air, on equipment or even from the odd stray hair, Brown warns. It is easiest to prevent contamination with a liquid levain. Liquid levain processors that ferment and store large quantities of cultures are available for commercial bakers.

In traditional sourdough production, three proofs are needed for a typical bread dough. The first proof, or culture proof, assures that the starter is at peak activity for leavening. The culture is always active at large-volume bakeries that continually produce dough, so for them, this culture proof time can be quick, only an hour or two. The second proof, or dough proof, takes 10 to 12 hours at 65°F to 70°F. This develops a good concentration of yeast, providing flavor as well as leavening. Finally, the loaf proof lasts two to four hours at 75°F to 85°F. This gives the dough further sour characteristics.

Traditional flavors, modern techniques

“Consumers continue on their quest for more variety in the taste of bakery products, but producing different types of sourdough in an industrial production environment has become a challenge,” says Kathryn Powers, marketing communications manager, Puratos USA. “The necessary investment, increased demand for food safety, flexibility, speed of product development and skilled labor are the challenges bakeries are facing today in striving to diversify their product portfolio using different sourdoughs.”

New ingredients have taken some of the complications out of the sourdough process, making it easier for commercial bakeries to produce a traditional loaf.

“Bakeries can produce a wide range of breads using Sapore^® products — fermented selected starter cultures developed by Puratos with cultures from diverse global regions,” Powers says. “The Sapore line covers a wide spectrum of flavor profiles endorsed by sensorial analysis. Whether using Sapore Aroldo for rye breads or Sapore Tosca for a unique Italian flavor note in crusty products, this range is an answer to consumer needs for more tasteful and fresher breads.”

Sapore products give bakers a ready-to-use solution in developing new bakery products. The cultures are natural and provide flavor, quality and consistency for unique bakery offerings. The products are available in liquid and powder form and are added directly to a bread formula with little impact on production processes or costs.

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