The soybean (Glycine max) is often called the miracle crop and is the world’s foremost provider of protein and oil. Soybeans are high in protein and contain beneficial phytochemicals, such as isoflavones. The mature soybean is about 38% protein, 30% carbohydrate, 18% oil, and 14% moisture, ash, and hull.
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 vegetable that contain complete protein.
Soy processors convert soybeans into products made from whole soybeans, such as tofu, tempeh, miso, natto, soy sauce, some soy flours, soy nuts, and soymilk. Other soybeans destined for more traditional food and technical products are graded, cleaned, dried, and cracked to remove the hull. Soybean hulls are further processed for animal feed or fiber additives for breads, cereals, and snacks.
Processors convert the remaining part of the soybeans, after the hulls are removed, into full-fat flakes that may be used in animal feed or processed into full-fat flour for a variety of commercial food uses. Immersing the full-fat flakes into a solvent bath extracts the crude soybean oil that is then degummed to separate lecithin from the oil. Lecithin is an emulsifying agent and when further processed is used in baked goods, dairy products, and instant foods. The extracted soybean oil, referred to as refined soybean oil is used to produce cooking oil, margarine, and shortening.
After the oil is extracted, the solvent is removed and recycled and the flakes are dried, creating an essentially oil-free, high protein product known as defatted soy flakes. Defatted soy flakes are ground into soybean meal and used to produce feed for animals, primarily poultry, swine, cattle, and aquaculture.
The defatted soy flakes are also the basis of a variety of soy protein products including soy flour, soy concentrates, and soy isolates.
Soy flour is produced by grinding and screening defatted flakes. Soy flour adds protein, improves crust color, and increases the shelf life of products of baked goods.
Soy concentates, used in protein drinks, soup bases, and gravies contain about 70 percent protein and retain most of the soybean’s dietary fiber.
Soy isolates, which yield at least 90 percent protein with little moisture, add texture to meat products and are used for their emulsifying qualities in many dairy-like products including cheese, milk, nondairy frozen desserts, and coffee whiteners. Isolates are also the primary protein sources in a variety of dietary beverages.