Soybean Protein Isolate
Soy protein isolate is a dry powder food ingredient that has been separated or isolated from the other components of the soybean, making it 90 to 95 percent protein and nearly carbohydrate and fat-free.
SPI (soybean protein insolate) is usually extracted from soybean defatted meal which is from normal hexane solvent extraction workshop. The used soybean is high quality, cleaned and husked. This defatted meal is called “white flake” in industry. Isolating soybean protein removes various nonprotein ingredients, retain protein and make dry basis protein content up to more than 90% ( Nitrogen*6.25 ).
There are mainly nine steps to produce SPI.
The first step is alkaline water extraction. Water temperature, PH value and dwell time is very important in this step.
The second step is separating extracted white flakes from solvent with the help of machines.
The third is acid precipitation with hydrochloric acid.
The fourth is separating whey from stick.
The fifth is adjusting to get multiple different functional protein isolate.
The sixth is neutralization with NaOH.
The seventh is heat treatment and stick adjusting.
The eighth is dehydration with spray drying.
The ninth is weighing and packing.
Nutritional and health benefits of soy protein isolate
Soy protein isolate is a complete vegetable protein. It contains all essential amino acids for growth and it is equal in quality to the protein in meat, milk and eggs. On the other hand, it has a very low fat content. Soy protein isolate may reduce the risk of coronary heart disease. There are also indications that soy protein can help in the prevention of osteoporosis, some cancers and menopausal symptoms. However, soy protein isolate may have less health benefits than whole soybeans or soy protein concentrates. During the production of soy protein isolate the protein is washed with alcohol, removing most of the isoflavones. The isoflavones have many health benefits such as improving arterial vasodilatation, lowering cholesterol and inhibiting atherosclerosis.