Fermented Soy Foods

For more than 2,000 years, the modest little soybean (Glycine max (L.) Merr., Leguminosae) has provided us with nutrition and healing power. New research shows that we derive the greatest benefits from soybeans when they are prepared in
traditional ways, especially when fermented.

Traditional soy foods are usually divided into two groups: fermented products such as miso, soy sauce, tempeh, and natto, and non-fermented products such as tofu and soymilks. In the name of health, North Americans are increasingly developing a taste for this Old World staple, in both the traditional and newer forms.

Fermenting the Soybean

In the soybean fermentation process, end results such as miso, tempeh, natto, and soy or tamari sauce are produced by a host of beneficial yeast, mould, and bacteria. Whole-food, fermented soy powders, milks, and yogurts are also cultured with multiple species of beneficial bacteria.The many benefits of soybean fermentation include the following:

• Improved digestibility. Unfermented soybeans are difficult to digest, partly due to the high amount of protein enzyme inhibitors and hard-to-digest sugar structures. During the fermentation process, the enzymes produced by the beneficial bacteria and other microbes break down, or predigest, the specific complex carbohydrates (sugars) found in soy and most other legumes. This process also renders the proteins more digestible and easier to assimilate than those
  in the whole soybean. For those with a compromised digestive system or difficulty digesting protein, this is especially helpful.
• Enhanced nutrition. Soy fermentation converts minerals such as calcium, iron, magnesium, potassium, selenium, copper, and zinc into more soluble forms and can also increase vitamin levels in the final product. Some beneficial yeasts, such as Saccharomyces cerevisiae, are able to concentrate large quantities of thiamin, nicotinic acid, and biotin, thus forming an enriched product.
• Medicinal benefits. Substances in fermented soy foods have been found to alleviate the severity of hot flushes, to have a protective effect against the development of cancer, to cause a reduction in cholesterol, and to inhibit the progression of atherosclerosis. The probiotic bacteria produced during soy fermentation are known to enhance healthy intestinal flora and correct digestive tract imbalances.
• Increased bioavailability of isoflavones. Isoflavones (phytoestrogens naturally occurring in soy) are converted by the bacteria into their "free" or aglycone forms for improved absorption and more effective usage within the body.

The Soybean "Conquers" America
In October 1999, the modest little soybean received a great deal of attention in North America when the US Food and Drug Administration authorized use of health claims about the role of soy protein in reducing the risk of coronary heart disease. As a result of this and some overstated health claims from other studies, the multinational soy industry has multiplied its efforts to find alternative uses and new markets for soybeans and soy protein foods. Billions of dollars have gone into researching, manufacturing, and advertising soy-based products, including a custom-designed soybean. Many top scientists around the world are expressing their concerns about genetically manipulated soy and other crops.

Today's North American soy cuisine has developed into something very different from its Asian predecessor. On supermarket shelves today we can find soy in everything from breakfast cereals to burgers to frozen desserts. Yet very few of these are natural, whole-food products. The ancient soybean was, for centuries, the quintessential "candidate for fermentation" requiring time-sensitive, careful processing in the Eastern world. It has now become mass produced and over-processed in the West.

Some health experts, such as well-known author John Robbins, are questioning the validity of consuming these new, nonfermented soy products. Robbins states, "The best way to take advantage of soy's health benefits is to follow the example of the traditional Asian diets and stick with whole [organic] foods…These are the soy foods that I prefer to eat-rather than the soy products made with protein isolates, soy protein concentrates, hydrolyzed soy protein, partially hydrogenated soy oil, etc. Whole soy foods are more natural and are the soy foods that have nourished entire civilizations for centuries."

Getting the Most from Soy Products

Choose organic fermented soy products such as tempeh, miso, natto, tamari, shoyu, and fermented whole soybean powder, milk, and yogurt. Genetically manipulated soy ingredients should be avoided whenever possible. In the US and Canada, almost all soy that is not referred to on the label as organic has been genetically manipulated. It is best to avoid hydrolyzed soy (vegetable) protein. New research suggests that soy formulas may be unsafe for infants.

It is relatively easy to cook with tofu, tempeh, miso, tamari, shoyu, and natto. Fermented soy powder, milks, and yogurt can be made into nutritional shakes and smoothies or included in pancake mixes, muffins, breads, and other baked goods. Cookbooks and recipes can make using soy even easier. Traditionally prepared, fermented soy foods are a healthy protein source.

Guide to Popular Fermented Whole Soy Foods

Miso: A rich, salty, fermented paste (made from salted soybeans alone or mixed with grains such as wheat, barley, and rice) that is cultured and aged.

Shoyu (soy sauce): Originally a by-product drained off miso, this dark brown liquid is typically used in Asian dishes. Tamari soy sauce is a by-product of miso without added grains.

Tempeh: A popular Indonesian food made by combining soybean with either rice or millet and a mould culture for 24 hours. It's a hearty, chewy, meat-like cake that can be grilled as a burger or added to a main dish.

Natto: A sticky, pasty-textured, slightly sweet-tasting soy ferment, eaten for breakfast or dinner as a topping on rice or added to vegetable dishes.

Fermented tofu: First a tough-textured tofu is made from cooked pur? soybeans processed into a custard-like cake; it is then fermented to make a white, creamy food resembling semi-soft cheese.

Fermented soymilk or yogurt: Made from soymilk that is fermented by probiotic bacteria, it can be used as a dessert or to make sour cream, cream cheese, or a form of ice cream.

Fermented soy powder: A whole-food, bacteria-fermented powder used in nutritional shakes, bars, or in baking, with all the nutritional value of traditional fermented soy.