While the original purpose of fermentation was to preserve food against spoilage, a controlled fermentation process can be used to create everything from cultures for dairy products—specifically yogurt and kefir, sour cream, buttermilk and cheeses—to bioengineering of flavors, manufacturing leavening agents and formulating enzymes or acidulants (such as lactic acid).
For many foods, preservation still is the main purpose of fermentation. Items such as Korean kimchi, Japanese miso, natto and tempeh and Mexican pozol are just a few. Vinegar and soy sauce are produced via fermentation, too. Today, fermentation science is one of careful and exacting control. It includes sensors to regulate temperature, oxygen, and pH levels; as well as near-infrared molecular spectroscopy probes to monitor levels of various desired metabolites.
Science also backs certain health benefits of fermentation. The body does this naturally, such as in the case of certain fibers and resistant starch. When these are fermented in the lower gastrointestinal tract, they produce chemicals that feed probiotic bacteria and create a cascade effect of healthful advantages.
Mimicking this natural fermentation can sometimes bring the same type of benefits. For example, the health and flavor properties of ginseng can be improved through fermentation. Active phytochemical components in ginseng called ginsenosides are transformed in the intestines by colonic bacteria into an end-stage, highly bioavailable metabolite called “Compound K.” Fermented ginseng extracts containing Compound K have been shown to have significantly faster and improved absorption in humans compared to non-fermented ginseng.
RFI Ingredients Inc. Blauvelt, N.Y., offers a line of fermented ingredients and the patented process, called FermaPro, that makes them. The company claims it "can ferment any dry material such as grains, grasses, seeds, vegetables and fruits using a variety of health-promoting bacterial or yeast cultures. The resulting fermented material is then drum-dried and milled in the same facility."
The company says fermented foods have numerous health benefits. "Makes many complex foods more digestible by breaking them down into readily digestible amino acids and simpler sugars" and "introduces helpful probiotics into our GI tract such as lactic acid bacteria."
While many ordinary foods become even healthier when fermented, due to improved nutrient bioavailability, fermentation also helps with elimination of antinutrients, such as phytic acid, and the increased production or creation of phytonutrients. The combination of increased technical precision in fermentation and greater awareness of the advantages has led to a surge in interest in fermentation-derived ingredients by processors and by the ingredient makers supporting them.
The essence of all individual fruits and vegetables contain hundreds of various complex volatile flavor compounds that give the products their characteristic flavor and aroma. The taste and perception of food products can be greatly enhanced with the astute use of a flavor or flavor system. Fermentation processes offer the food industry the opportunity to realize cost savings on economies of scale, the ability to produce nature-identical flavors at a reasonable cost, and also limit price fluctuations due to raw material supply concerns.
The power of yeast
Fermentation using yeast cells is a cost-effective method of commercially manufacturing chemicals such as flavors and antioxidants. Take resveratrol, an antioxidant naturally present in red wine and believed to have anti-aging effects. (It already is self-affirmed GRAS in the U.S.) Most resveratrol products on the market are low-purity extracts of Japanese knotweed (Fallopia japonica) manufactured in China. However, the Reinach, Switzerland-based biotech firm Evolva SA recently received EU approval for a yeast-derived fermented resveratrol ingredient as a novel food. Evolva is also busy commercializing fermentation routes for stevia, vanillin and even saffron.
Vanilla is one of the world’s most important flavors and is the second most expensive spice, after saffron. Growing and harvesting vanilla seed pods is labor-intensive, sometimes taking between six to eight months for full flavor development. The vanilla flower lasts only about one day, sometimes less, so growers have to inspect their plantations every day for open flowers, and then carefully hand-pollinate them.
However, vanillin (4-hydroxy-3-methoxybenzaldehyde), primarily responsible for the characteristic flavor and odor of vanilla, can be produced via a controlled fermentation process, significantly lowering production costs and yielding a high-quality product.
Givaudan Flavors Corp. , Cincinnati, recently submitted a patent application for a fermentation process in which green, ripe but uncured vanilla beans are incubated with Bacillus subtilis in order to convert glucovanillin to vanillin. This process produces “a comparable or higher yield than traditional processes but with a more consistent, fully developed and complex sensory profile, without the presence of off-notes,” as described in the filing.
How sweet it is
Stevia is another plant-derived ingredient that is beginning to be produced by fermentation. The plant contains a number of steviol glycosides or rebaudiosides that provide the characteristic sweetness, but they also differ in sweetness, intensity and aftertaste perception. Currently the most popular commercialized extract is rebaudioside-A.
There are several companies developing and optimizing the process for manufacturing fermented steviol glycosides. While the FDA has considered the reb-A extract to be GRAS for food, beverage, confectionery and table-top sweeteners since 2008, it has not approved the use of fermented steviol glycosides. Blue California, Rancho Santa Margarita, Calif., has developed a natural process for its stevia extract called Good&Sweet Reb-A 99%.