All About Soy
The Basics of Soy
The soybean is one of a large family of plants called legumes. Legumes tend to be higher in protein than other plant foods - in fact, the mature soybean is about 42% protein, 33% carbohydrate, 20% oil, and 5% hull.
Soy's Protein Power
Among all legumes, the soybean stands apart. Both mature and green soybeans are protein powerhouses. Compare the grams of protein in one-half cup of green or mature soybeans to the same size serving of several familiar plant foods, including other legumes like pinto, Lima, and kidney beans, black-eyed peas, and English peas. Not only does the soybean contain more protein than other plants, the protein it contains is of higher quality. In addition, the soybean is the only plant source of protein considered a complete protein. This means it not only provides all the essential amino acids your body must get from food, but these essential amino acids are also in the right balance to meet human needs.
From Soy Bean to Soy Shake
For many Westerners, eating soybeans or even traditional soy foods regularly would mean drastic changes in eating habits. Fortunately, today's soy protein ingredients allow people to get all the benefits of soy - in a wide variety of favorite foods like soy "burgers," drinks and shake mixes, soy protein bars and more.
All these soy foods contain soy protein ingredients, which include soy flour, soy protein.
When mature soybeans arrive in the processing plants, removed are the damaged beans and any foreign material. To remove the hulls the beans are cracked. The remaining soy chips process into flakes - these flakes retain the oil found in the soybean.
Soy Flour
Full-fat or natural soy flour is about 40% protein, based on dry weight. Grinding the full-fat soy flakes turns it into a powder. De-fatted soy flakes are the starting materials for making the three primary soy ingredients: soy flour, soy protein concentrate and isolated soy protein. Grinding the de-fatted soy flakes to a fine powder creates the de-fatted soy flour. At 50% protein (based on dry weight), de-fatted soy flour is the least refined of the three primary soy-protein ingredients.
Soy Protein Concentrates
Soy protein concentrates are 70% proteins, based on dry weight. These are made from de-fatted soy flakes that have had most of the sugars removed but have kept much of the soy fiber. Soy protein concentrate is lower in carbohydrate than soy flour.
You can remove the sugar from soy flakes in two different ways. The most common method uses alcohol, the other uses water.
When using alcohol to remove the sugar, removing the solvent is the first step before making soy protein concentrate. As you will soon see, the use of alcohol extraction in the manufacture of soy protein concentrate is an important issue. Alcohol processing not only removes the sugars from de-fatted soy flakes, it also removes valuable alcohol-soluble phytochemicals that naturally occur in soy.
However, when water removes the sugars from the flakes, there is a good retention of the naturally occurring phytochemicals in the final product. After the removing the sugar by the water washing process, drying the mixture makes the final product.
Isolated Soy Protein
At 90% protein (based on dry weight), isolated soy protein is the most concentrated form of soy protein. Manufacturers make most isolated soy protein using water to extract sugar from de-fatted soy flakes. The protein is then precipitated and dried.
Here again, excessive processing can wash away some of the phytochemicals that were originally present in the soybean.
The Facts about Phytochemicals
There are thousands of phytochemicals, or "plant chemicals" present in plants. The type of processing used to manufacture soy protein ingredients is getting a lot of attention. Alcohol processing or extensive water washing can remove substantial amounts of these substances - and that raises attention because a number of these phytochemicals are under study for their potential health benefits.
Learn About Labels
To make sure you are getting soy protein and naturally occurring bioactive components in your soy-based foods, read labels carefully. Be sure to choose products made with ingredients that retain these substances.
Check to see if the product contains isolated soy protein. Do not forget to compare the fat and calories. You want to be sure you are getting the most protein with the least amount of fat and calories.
