Soy Protein Concentrate
Soy protein concentrate is made by removing a portion of the carbohydrates (sugars) from dehulled and defatted soybeans. Normally, about 750 kilograms of soybean protein concentrate can be obtained from one metric ton of defatted soybean flakes. There are different soy protein production methods
. The most frequent method used is alcohol extraction although this method results in most loss of the soy isoflavones. However, when the water extraction method is used to remove the sugars, there is a good retention of the isoflavones in the final product. Soy protein concentrate retains most of the fiber of the original soybean. Soy protein concentrate is very digestible and therefore suited for children, pregnant and lactating women and elderly. It is in pet foods and milk replacers for calves and pigs.
Use of soy protein concentrate
Soy protein concentrate is widely used as functional or nutritional ingredient in a wide variety of food products, mainly in baked foods, breakfast cereals and in some meat products. Soy protein concentrate is used in meat and poultry products to increase water and fat retention, and to improve nutritional values (more protein, less fat). It is even used for some non-food applications.
Soy protein concentrate should contain at least 70% protein on a moisture free basis. The protein can have different solubility characteristics, depending on the extraction method. Some applications, such as drinks, require a highly soluble protein. The soy protein concentrate made with the alcohol wash will have low solubility which can be increased by further processing, for example by neutralization of acid washed concentrate with alkali. Soy protein concentrate can be found in different forms: granules, flour and spray dried. Most of the characteristic beany flavour is usually removed by the extraction process, resulting in bland tasting end products. The flatus-producing sugars raffinose and stachyose can also be removed by the solvents used in the production of soy protein concentrates.