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Soybean Nutrition

Nutritional and Health Benefits of Soybeans

Soybeans contain all three of the macro-nutrients required for good nutrition: complete protein, carbohydrate and fat, as well as vitamins and minerals, including calcium, folic acid and iron.

Soybeans are the only common plant food that contain complete protein. Soybean protein provides all the essential amino acids in the amounts needed for human health. The amino acid profile of soy protein is nearly equivalent in quality to meat, milk and egg protein.

One Serving* of Soy

*Always check the nutrition facts label of the product you purchase. Soymilk and tofu, for example, can vary widely in nutrient content depending on the type and brand.

Nutritional Analysis:

• Soybean Oil
• Soy Protein
• Soy Protein Products
• Soy Fiber
• Whole Soybean Foods
• Traditional Asian Soy Products
  

Soybean Oil - Nutritional Analysis

Soybean oil is 61% polyunsaturated fat and 24% monounsaturated fat which is comparable to the total unsaturated fat content of other vegetable oils (~ 85%). Like other vegetable oils, soybean oil contains no cholesterol.

• Polyunsaturated vs Saturated Fats
  Excessive intake of any fat is undesirable. Nutrition experts recommend limiting total fat consumption to 30% or less of the total daily calories and limiting saturated fats to 10% or less. Saturated fatty acids raise blood cholesterol which can thicken arterial walls and increase the risk of heart disease.

In both clinical trials and population studies, polyunsaturated fats in the diet have been shown to actively lower serum cholesterol levels (Hegstad et al., 1992).

Other research collected over many years from around the world has shown that populations with diets low in saturated fats have the lowest death rates.

As a result, the replacement of saturated fats with reasonable amounts of polyunsaturated fats, such as those found in soybean oil, is recommended.

• Essential Fatty Acids
  Soybean oil is rich in polyunsaturated fatty acids, including the two essential fatty acids, linoleic and linolenic, that are not produced in the body. Linoleic and linolenic acids aid the body's absorption of vital nutrients and are required for human health. These two essential acids are also precursors to hormones that regulate smooth muscle contraction, blood pressure, and the growth of healthy cells.

  Pure soybean oil is about 50% linoleic acid and 8% linolenic acid.

• Hydrogenated Soybean Oil
  Hydrogenation is used to solidify soybean oil for the manufacture of margarine. This process increases stability of oils and to raises the melting point of soybean oil shortening. Hydrogenation changes the chemical composition and physical properties of oils and affects the nutritional value. The degree of change in nutritional value depends upon the amount of hydrogenation necessary to produce the final product and the reduction of polyunsaturates that occur.

  The hydrogenation process also creates trans fatty acids from cis unsaturates by rearranging hydrogens around the double bonds in a monounsaturated or polyunsaturated fatty acid.

Soy Protein – Nutritional Benefits

Almost 40% of the calories in soybeans are derived from protein causing soybeans to be higher in protein than other legumes and many animal products. The quality of soy protein is highly notable and approaches the quality of meat and milk. Unlike many other good sources of protein, soybeans are low in saturated fat and are cholesterol-free.

Soy Protein Products

Defatted soy flakes, a product resulting from the oil extraction process of soybeans, are the basis of a variety of soy products including soy flour, soy concentrates, and soy isolates.

• Defatted soy flours are about 86% protein and have very little moisture. They contain no fiber, carbohydrates or fat. Soy flours are very different from wheat flour and can not be substituted directly fro all the wheat flour in a recipe. Replacing about 15% of the wheat flour with soy flour gives a nutty flavor, darker crust, and moister crumb.
  
• Soy concentrates contain about 65% protein and retain most of the soybean's dietary fiber. Concentrates also add texture and help foods retain moisture.
  
• Soy isolates contain about 90% protein and are the most versatile of all the soy protein products. Isolates are used to add juiciness, cohesiveness, and viscosity to a variety of meat, seafood, and poultry products. Soy isolates are the chief component of many dairy-like products, including cheese, soymilk, infant formula, non-dairy frozen desserts and coffee whiteners. They are used to add texture to meat products and are valued for their emulsifying properties. Soy isolates absorb five times their weight in water. Isolates can be used to enhance both the nutritional quality and taste of meat products. This is especially true for soy used to enhance the flavor and nutritional quality of tough meat. Soy isolate is excellent for improvement of sensory attributes of whole meat products. Roasts and hams that contain soy isolates are juicer and more nutritional. Soy isolates can also be used as an ingredient to supplement or replace milk powder. In addition, isolates are commonly used in dairy products such as beverages, frozen desserts and imitation cheeses.

Soy Fiber

Soybeans, especially the outer hull, are an excellent source of dietary fiber (6 grams fiber per 1 cup cooked soybeans).

During processing, the soybean hull is typically removed. This extracted hull can be further process to create a fiber additive for breads, cereals and snacks.

Soybeans contain both soluble and insoluble fiber. Soluble fiber may help lower serum cholesterol and control blood sugar. Insoluble fiber increases stool bulk, may prevent colon cancer, and can help relieve symptoms of several digestive disorders.

Whole Soybean Foods

• Full fat flour is made from whole soybeans and therefore has the same fat, protein and dietary fiber content as the whole bean. Full fat flour is used for doughnut mixes, pie crusts, pancake batters and other baked goods.
  
• Soymilk is made from ground soybeans that are mixed with water to form a milk-like liquid. Soy milk can be consumed by people who are dairy sensitive or by strict vegetarians who eat no animal proteins. Soymilk is an excellent source of protein, B-vitamins and iron, and if fortified, provides adequate calcium. It has low levels of saturated fat and no cholesterol.

Traditional Asian Soybean Foods

For centuries, soybean have been mainstays of healthy diets throughout Asia and the East. today, Asian whole soybean foods are slowly gaining acceptance in the West as a unique source of nutrition that can help reduce saturated fat in the diet.

Whole soybean foods are high in protein, fiber and unsaturated fat, and rich in vitamins and minerals. They also show many anticarcinogenic properties related to the unique benefits of soy isoflavones, phytochemicals which exert biological effects in humans and other aminals.

• Tofu (soybean curd) is a bland, cheese-like cake formed from soymilk by adding a coagulant (typically calcium sulfate) to the milk to form curds that are shaped and pressed into cakes. Depending on the coagulant used, tofu is rich in minerals and is an excellent source of high-quality protein, polyunsaturated fats (including linoleic and linolenic acids) & B vitamins. Versatile and nutritious, tofu can be used in soups, salads, pastries, sandwiches, and spreads. It can also be used as an alternative to yogurt or soft cheese.
  
• Miso is a thick, high-protein paste made from soybeans, salt and a fermenting agent (usually an Aspergillus oryzae mold culture), that is similar in taste and color to soy sauce. Sometimes a grain, such as rice and barley, is fermented with the soybeans for additional flavor. Miso is popular as a soup and breakfast drink in Japan.
  
• Natto is made of fermented, cooked whole soybeans, and offers nutritional values similar to those found in miso. It has a sticky, viscous coating and is strong-smelling, with a cheesy texture. It is used as a spread or in soups.
  
• Tempeh is made of whole, cooked soybeans infused with a culture to form a dense, chewy cake. It is a good source of fiber protein, polyunsaturated fats and lecithin, as well as useful amounts of calcium, iron, magnesium, potassium, and some B vitamins.
  
• Soybean sprouts are rich in vitamins A, B and C, and are eaten raw in salads or cooked.
  
• Soy sauce is the most widely recognized soybean food. Soy sauce is fermented for about 18 months as a mixture of whole soybeans, wheat flour, and fermenting agents, such as yeast. The resulting liquid is extracted and processed. Soy sauce adds sodium and flavor to foods.