Robert M. Kerr

Food and Agricultural Products Center

 

By Nurhan Dunford, FAPC Oil/Oilseed Specialist

 

Although fermented foods have been around and consumed for centuries, the recent quest for healthier diets is generating a renewed buzz about their health benefits as a good-for-you food. Market share of fermented foods and beverages has been growing over 10% annually during the last five years. The number of products with “fermented” claims also are on the rise on the grocery store shelves.

 

The origin of fermentation process is as old as human civilization. Carbohydrates such as starches or sugars are converted into alcohols and acids by beneficial bacteria, yeasts, or other microorganisms during fermentation. 

 

Many people are familiar with some well-known fermented foods such as sourdough bread, cheese, soy sauce, yogurt, coffee, sauerkraut and vinegar. Many cultures around the world have their own traditional fermented products that you might not have heard of before. Slavic fermented grain beverage kvass, Turkish beverage boza and skyr from Iceland are only a few of the less known fermented products with cultural roots.

 

The unique tastes and flavors of fermented products are due to the free amino acids and flavor compounds formed during fermentation. The savory and umami flavors of fish and soy sauce, the tangy flavor of kefir, the cultured dairy products, and the tart and sour flavors of vinegar and fermented vegetables all are generated during fermentation.

 

Digestive and gut health are among the top claims on fermented food packages. Fermentation also improves safety of the foods. Fermentative bacteria, yeasts and molds produce lactic acid, acetic acid, propionic acid, ethanol and bacteriocins which inhibit the growth of spoilage and pathogenic microorganisms naturally present in foods and preserve and extend the shelf-life of the foods.

 

Charles Edward, a food science professor at Washington State University, highlights the food safety implications of the fermented products.

 

“For instance, there is not one pathogen that will grow in wine, not one,” Edward said.

 

Grains are important sources of proteins, carbohydrates, vitamins, minerals and fiber in human diets. Yet, some consumers find the organoleptic attributes of grains, such as their coarse texture, unpleasant. Although rich in health beneficial phytochemicals, some of the grain components can be hard to digest. The presence of anti-nutrients such as phytic acid, tannins and polyphenols in some grains is a concern for some. Anti-nutrients bind nutritionally important minerals and proteins making them unavailable for metabolism.

 

Many of the undesirable sensory and nutritional attributes of cereal foods can be improved through biochemical reactions taking place during the fermentation process. Foods enriched in probiotic microorganisms like lactic acid bacteria, or bifidobacterial, can be produced from cereal grains through fermentation. Probiotic organisms are known to improve metabolism, lower cholesterol levels in blood and stimulate immune system.

 

Natural fermentation of cereals decreases levels of carbohydrates and some of the non-digestible poly and oligosaccharides in the final product. Fermentation also boosts bio-availability of vitamin B and leads to synthesis of beneficial amino acids. There are studies indicating fermentation of rice and buckwheat bran with Propionibacterium freudenreichii produces significant amount of vitamin B12, which is available from animal sources but not present in grains potentially benefiting vegan consumers. Enzymes released during cereal fermentation degrade anti-nutrients freeing iron, zinc, calcium, magnesium and proteins and making them available for absorption.

 

Fermented foods, beverages and ingredients based on grains are getting a lot of attention, especially from young consumers who are willing to try different flavors and exotic foods.  Fermented oat-based and quinoa-based beverages, corn-based yogurt, chickpea and faba bean flour are some of the products on which food scientists are working with. Dupont Nutrition & Health is offering cultures specifically developed for cereal-based, specifically oat-based and rice-based, fermented food and beverage production. According to the company, the strains are dairy, lactose, allergen and soy free, and are not genetically modified.

 

A new trend is to reformulate some of the traditional fermented foods to make them more appealing to today’s consumers or create new formulations. My favorite example is koji, which is traditionally used in Oriental cuisine to add flavor to grains. An enzyme-rich sauce or liquid, shio-koji is produced by growing koji, which is an edible mold, on a grain such as rice and then dipping it in brine. The final product is used as a seasoning or marinade to break down food proteins and carbohydrates into flavor-enhancing molecules. Koji is being transformed to boost the umami flavor of nontraditional foods without using additives. For example, koji has been used to make a miso-like paste from sunflower seeds, pistachios and chickpeas instead of the traditionally used soybean. Another example is to produce flavors ranging from soy sauce-like to chocolate, coffee and caramel by roasting koji infused grains.

 

Although koji has long been used to add flavor, there are claims it can also be used to enhance health benefits of some foods. Some argue the enzymes, proteases and amylases released by koji potentially could remain active even after ingestion and still function in the acidic conditions of the stomach, helping the digestion of foods.

 

As the interests in fermented foods are increasing, we see numerous recipes and kits for preparing fermented foods at home on social media and the internet. It is very important to understand many things can go wrong if you do not have the right supplies and do not follow appropriate procedures. If the preparation conditions are not right, desirable edible organisms may not grow, but most importantly, spoilage or food poisoning microorganisms may invade the preparation. For example, Listeria monocytogenes, a foodborne pathogen, has been isolated from various plant foods and fermented materials. Insufficient acid production and anaerobic fermentation conditions may create conditions that promote growth of harmful bacteria Clostridium botulinum that can produce fatal neurotoxin. The toxin causes botulism, a serious paralytic illness that is considered a medical emergency. It also is helpful to keep the utensils and the preparation area in good sanitary condition to ensure safety of the final fermented product.