Starter cultures and sours experience a renaissance as artisan baking popularity increases.
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.
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.
“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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New products from Lallemand also are aimed at improving the production rate and reliability of sourdough breads. Lallemand promotes two product lines: Florapan® freeze-dried starter cultures and ready-to-use (RTU) cultured flours from the German sourdough specialist BÖCKER.
Florapan® starter cultures are used to start, or seed, the fermentation of any flour and water mix, such as a slurry or a dough, in a perfectly controlled and reproducible way. The fermentation can take place in pails, troughs or tanks, from room temperature to 90°F. As there is no need to ship flour and water — because both are readily available in bakeries — they are the cheapest way to produce a levain. The dosage of the starter is as low as 0.1 percent of flour weight, and they are stable for one year in the refrigerator. Bakers can diversify by choosing the type of flour to be fermented: wheat, rye, spelt, buckwheat, barley, oat, whole grain, organic, etc.
BÖCKER's RTU cultured flours are an answer for even more convenience, diversification and flexibility. The cultured flours are available in liquid, powder and paste forms and may be used in combination to vary the flavor profiles produced. Add them directly to the dough while mixing. The powder products also are well suited for millers and blenders to add a natural flavor to their flour blends and bread mixes. Dosages range from 2 percent of flour weight for powders up to 15 percent for liquid products.
Using a RTU product provides reliable quality, a range of flavors, convenience and eliminates fermentation. Downsides include increased cost, no fermentation power and increased storage costs.
Although most commonly used in breads and baguettes, starter cultures also can be used in bagels, muffins and pretzels, to give your bakery a quality offering for demanding consumers. These specialty items also benefit from the flavor and texture advantages that starter cultures provide. However, health claims about the benefits of consuming sourdough bakery items should be avoided, as they require extensive and expensive clinical study substantiation.
As tempting as it might be to state that breads leavened with natural yeast provide health benefits above and beyond carbohydrate nutrition, Wood cautions against making any health claims, as they are not yet scientifically proven. No federal controls regulate what can and cannot be labeled sourdough. Some bakeries market breads as sourdough that are merely breads acidified with vinegar or chemical sours. These are not fermented products, rather blends of fumaric acid, malic acid, sodium diacetate or other chemicals that produce a sour flavor in bread. Instead, Wood recommends bakers promote the consumption of true sourdough baked products based solely on delicious flavor. That is a claim that has gone unchallenged for millennia.
CULTURES (STARTERS) are preparations of selected lactic acid bacteria (usually freeze-dried) and aromatic dry yeast. They are very stable, high-concentration live cultures to seed a liquid or stiff flour-water mixture in a controlled and reproducible way. The resulting product is a cultured flour, also called levain or sour preferment.
READY-TO-USE CULTURED FLOURS are fully fermented products added directly to the dough. A specialized facility mixes flour, water, lactic acid bacteria and yeast, then stabilizes it by drying, salting or further acidifying. They have no more capacity for further fermentation or gas production. They are available as liquid, paste or powder. Some are 100 percent natural, others may contain chemicals.
SOURS are blends of flour and starch (carriers) and chemical acids that require labeling. They usually don't contain fermented flour, so have a narrow flavor profile, delivering a simple and acidic bite. Free acids in sours tend to weaken the dough structure.
HOMEMADE STARTERS are flour and water mixtures that have been fermented by the naturally occurring microorganisms found in cereals, fruits and the bakery environment. They have to be replenished (fed with fresh flour and water) and refrigerated to avoid rotting, over-acidification and loss of proof power. They are used to inoculate a larger flour-water mix that can be replenished indefinitely, but their complex microorganism population balance is difficult to maintain and the loss of some of the original starter characteristics is unavoidable.
courtesy of Lallemand Baking Solutions
While all sourdough cultures will leaven all types of flours, some are better than others for producing certain flavors for production of specific breads.
| Country | Name | Flavor Profile |
|---|---|---|
| France | Levain | Acetic, fruity |
| Germany | Kesselsauer or Sauerteig | Strong acetic |
| Poland | Zakwas | Mildly acetic |
| South Africa | Soetsuur | Sweet and sour wheat notes |
| Japan | Sake Dane | Cooked wheat sponge |
| USA | Sponge | Fruity flavors |
| USA | San Francisco Sourdough | Strong acetic notes |
| Lithuania | Scalding | Sweet rye notes |
Global sour variation courtesy of Puratos USA