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Benefits of Bacteria
bakemag.com, March 2012
by Bob Sims

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Bread serves as one of the staples of American food. A paradox exists in the simplicity of ingredients compared to the complexity of the chemical reactions that occur during the process of making sourdough breads. Making the bread requires only a few ingredients, but it’s the nature of the ingredients that create reactions with one another, giving bread its unique textures and flavor.

Two things present in sourdough bread that greatly affect flavor and structure are yeast and bacteria. “When we’re thinking about bacteria it’s really more relevant to sourdoughs than to dough that are using commercially produced yeast,” says Melina Kelson of Kendall College and member of the Bread Bakers Guild of America board of directors. Along with the wild yeast come a variety of bacteria that help to stabilize the starter.

The most important bacteria that travel with the yeast are lacto bacillus. “There are essentially two different styles of lacto bacillus, there’s homo-fermentative and hetero-fermentative,” Kelson says. The homo-fermentative variety produces lactic acid and the hetero-fermentative produces both lactic and acetic acid. The two varieties of bacteria produce different flavor qualities in the bread, and the fermentation process of the dough can be manipulated to favor one or the other.

To bring out the acetic qualities with hetero-fermentative bacteria, maintain the culture at a lower temperature, about 50-55°. With this method, the bread will develop a sharper, vinegary flavor. “That’s something you see typically done throughout Europe,” Kelson says. At room temperatures — 70-75°, the homo-fermentative bacteria flourish, producing tangier yogurt and fermented dairy type flavors along the sides of the tongue.

Encouraging the acidity of both fermentatives bring other desirable qualities along with flavor. “It strengthens gluten bonds, so it impacts the texture of your product, giving more chew and more crustiness,” Kelson says. “Anytime you’re acidifying a portion of your flour by fermentation, whether it’s using wild cultures or not, you are going to get that benefit.”

Also, when fermenting anything for an extended period of time an enzymatic change takes place. Known as proteases, this change is responsible for making the dough stretchier rather than elastic. “You will find in these doughs that they can be a little easier to shape if you’re trying to gain length in something,” Kelson says. “When you go to bake it, it looks like it’s collapsing and then you get this dramatic oven-spring.”

The production of acids through the bacterial fermentation process in bread offers extended shelf life — an advantage to retail baking that goes well with flavor and texture. While flavor represents the most important factor to a bakery, it becomes irrelevant if the product stales and expires. “The acids help retard staling,” says Brian Wood, owner of Starter Bakery in Oakland, CA.

Strong, flavorful bread that is easier to shape with a longer shelf life gives the retail baker a better option for customers. Using a yeast with acid producing hetero- and homo-fermentative lacto bacillus bacteria will improve the qualities of your bread and give your bakery extra advantages.

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