Bakers and eaters alike may notice a particular quirk of sourdough bread: it doesn’t go moldy like conventionally leavened bread. Now, scientists have figured out why the sour stuff is mold-resistant, and they may be able to apply it to other foods to halt the fungus among us.
Sourdough is different from traditional bread because it takes an extra fermentation step, which uses lactic acid bacteria to metabolize sugars and add that particular spunky flavor. The researchers found that during sourdough production, lactobacilli bacteria convert another acid found in bread flour—linoleic acid—into hydroxy fatty acids that resist fungus.
By harnessing special bacteria, bakers may be able to reduce the amount of preservatives from bread, making it taste better. They also may be able to create tools to control fungi in malting and plant production. Their research was published recently in the journal Applied and Environmental Microbiology.
"Our research potentially provides a very useful tool to the food industry, says Michael Gaenzle, a professor of Agricultural, Food & Nutritional Science at the University of Alberta. "Mold growth limits the shelf life of bread, but also of other foods," and the research could help extend the ability of foods to hang around for longer.
Gaenzle adds that hydroxylated fatty acids like the ones he is studying are a class of compounds that has to date not been considered as an antifungal agent in food preservation.
To move the research forward, Gaenzle must first repeat the results after replacing linoleic acid—not commonly used as food ingredient and quite expensive in purified form—with a plant oil rich in linoleic acid. Second, he wants to find out why the lactobacilli convert linoleic acid to hydroxy fatty acids. "If we understand that question, we can further optimize the conversion," he says.
Shelf-stable food is a goal of many companies. A Texas business known as MicroZap says that it has created bread that stays fresh for two months. They zap the loaves with microwaves for about 10 seconds, which kills any potential mold spores.
The Natural Resources Defense Council estimates that, food losses inside grocery stores in the U.S. totaled an estimated 43 billion pounds in 2008, 10% of all foods supplied to retail outlets. Most of those losses come from perishable items like bread.
Microzap is also examining ways to zap pet food, rendering it Salmonella-free. They are also looking into technology to rid linens and comforters of bedbugs.