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%.
“We expect to produce single compounds (by fermentation) in the near future and can offer unique blends of steviol glycosides, in different ratios, designed to meet customers’ specifications for particular applications,” says Cecilia McCollum, Blue California’s executive vice president. “Fermentation can ensure sustained availability and consistent quality and can reduce price fluctuations caused by natural disasters or agricultural problems that contribute to the scarcity of the starting raw materials.”Netherlands-based DSM Food Specialties, announced its plans to introduce steviol glycosides produced through fermentation sometime next year. The company notes it’s “a sustainable, efficient and cost-effective process to meet market growth.” Officials also point to other advantages, including that the sweetener can be produced “anywhere in the world very efficiently,” utilizing fewer raw materials, requiring less arable land and consuming less water. And for processors, an advantage of fermentation-derived stevia is that the ingredient can be more finely customized for specific taste and calorie level needs.
“There actually are 30-50 glycosides present in the leaf; of this amount, 10-15 are well characterized,” says Robert Brooke, CEO of Stevia First Corp., Sacramento, Calif. The company is marketing its next-generation stevia extracts as “Beyond Reb A,” including rebaudiosides D and M and perhaps other rebaudiosides.
“These glycosides have different solubilities and sweetness profiles,” explains Brooke. “For example, rebaudioside-D has been shown to have a cleaner sweetness profile, with less lingering aftertaste. The D and M compounds are present at low concentrations, about 1/20th-1/50th the level of reb-A in the stevia leaf. This makes them currently more expensive than HFCS [high-fructose corn syrup] and other high-intensity sweeteners. However, we are attempting to solve this challenge by developing a fermentation process in the U.S.A.”
Brooke further explains that the company’s fermentation process can produce these rebaudiosides at “sufficient quantities while controlling costs.” He also points to the benefit of having A, D, and M rebaudiosides that can be blended together in different ratios “to meet the challenges of diminishing aftertaste issues and having a sweetness profile comparable with HFCS and other high-intensity sweeteners.”
Cargill Inc., Wayzata, Minn., recently formed a partnership with Evolva to develop and commercialize stevia ingredients via fermentation. In late 2013 the companies announced their program was moving into pilot-scale ahead of schedule. Both companies believe this novel fermentation-derived stevia product can deliver an improved sweetness profile as compared with traditional steviol glycosides.
Fermentation on the rise
Most consumers believe sourdough bread originated in San Francisco. However, the oldest recorded use of sourdough is from the time of the ancient Egyptians. Sourdough uses a dough containing a Lactobacillus culture in symbiotic combination with yeasts to generate its characteristic taste and aroma. The most commonly used yeast species in the production of sourdough are Kazachstania exigua, Saccharomyces cerevisiae and Candida humilis.
Caravan Ingredients Inc., Lenexa, Kan., has added Pristine, a wheat fermentation enhancer, to its line of clean-label products. This enhancer is made from a dried, naturally fermented wheat sour bacteria. It can be used at low levels for a hint of flavor or at higher levels for a more robust flavor. Pristine is an Italian bakery base, used at up to 4 percent of volume to produce classic artisanal Italian and Ciabatta breads and rolls, as well as baguettes.
This sourdough-style base works well with automated equipment and aids in producing a clean label product. It is an easy-to-use flavor designed to eliminate the need for "messy wet sours" and lengthy fermentation processes. Moreover, it provides exceptional fermentation flavor with variability for the baker and saves time and labor costs.
Inactive nutritional yeasts, yeast extracts, cell wall fractions and enriched yeasts have been developed for niche applications in the food industry for flavor development, nutritional and vegetarian preparations, pet foods and more. Lallemand Inc., Montreal, has developed several products to add depth of flavor to a variety of foods. These ingredients are used in many food preparation applications for their nutritional profile and as savory flavor contributors.
Another inactivated yeast is Torula (Candida utilis; formerly Torulopsis utilis, Torula utilis). Torula is widely used as a flavoring in processed foods and pet foods. It is pasteurized and spray-dried to produce a fine, light grayish-brown powder with a slightly yeasty odor and gentle, slightly meaty taste. Inactive yeasts are high in the antioxidant glutathione, and are used for dough relaxation in the baking industry.
Some yeast extracts also promote color intensity and reduce or replace MSG and salt content, while imparting umami (the fifth basic taste) and kokumi tastes. Recently, the European Food Safety Authority (EFSA) issued a positive opinion on the use of vitamin D2-rich baker’s yeast (Saccharomyces cerevisiae) in yeast-leavened breads and rolls as a contributing factor for reducing vitamin D deficiency.
Soy sauce is a traditional fermented ingredient in east and southeast Asian cuisines, where it is used in cooking and as a condiment. Soy sauce has a distinct yet basic taste of umami, due to the naturally occurring free glutamates. Just as with a fine wine, soy sauce is typically aged for at least six months before it is bottled, although some are aged longer.
Soy sauce is made from a fermented paste of boiled soybeans, roasted grain (such as wheat), brine and moulds with high proteolytic capacity, such as Aspergillus oryzae or Aspergillus sojae. Another type of fungus, Aspergillus tamari, is used for brewing tamari, a variety of soy sauce.
Other types of microorganisms and yeasts also are added in the culture to convert some of the sugars to ethanol. This mixture then undergoes secondary reactions to make additional flavor compounds.
The brine (salt solution) controls the propagation of bacteria during the brewing process and acts as a preservative. After fermentation, the paste is pressed to produce a liquid, which is the soy sauce, and a solid by-product, which is often used as animal feed. A study by the National University of Singapore showed Chinese dark soy sauce contains 10 times the antioxidant levels of red wine and can help prevent cardiovascular diseases.
Back to RFI Ingredients' FermaPro process: FermaPro Black Garlic is one resulting product. First, the garlic undergoes a primary microbial fermentation from the natural bacteria present. Then, the secondary fermentation process ages the garlic under mild heat, resulting in the subsequent activation of the enzymes. This fermentation process turns the color from white to black and changes the flavor from pungent to sweet and savory. The whole garlic clove matrix is preserved and then freeze-dried to protect the potency of the important phytochemicals.
Nothing is added or removed from the garlic other than peels and water, so it’s considered a “whole-food” product. Additionally, these fermentation reactions improve garlic’s immune-enhancing activity and antioxidant potency, doubling the oxygen radical absorption capacity (ORAC) value as compared with regular garlic.
During the aging process, unstable and potent compounds such as allicin are converted to S-allyl cysteine (SAC). Unique new antioxidant compounds such as tetrahydro-betacarbolines, structurally similar to flavonoids, have also been identified, notes Jeff Wuagneux, president and CEO of RFI Ingredients.
Animal and in vitro studies have provided evidence that black garlic may also protect the cardiovascular system by maintaining healthy cholesterol levels and blood pressure, as well as reducing platelet aggregation and vascular calcification. Clinical studies have shown that LDL-cholesterol (the bad guy) isolated from subjects receiving 2.4 g of black garlic daily for seven days was reported to be more resistant to oxidation than LDL isolated from subjects receiving no supplementation.
People around the world have been enjoying fermented foods for centuries. Educating American consumers about the many health benefits of these ingredients will ensure that this segment of the food industry experiences continued growth.