What is Protein Isolate? Including Whey Protein & Soy Protein

As its name implies, protein isolate is a material in which the protein has been somehow isolated and concentrated. Protein isolates are rich in proteins, one of the major nutrients needed for proper nutrition. For example, soy protein isolate may have up to 90-95% of protein, almost no fat and little carbohydrates.

Although there are plenty of foods from which you can get your daily needs of proteins (meat, eggs, milk, cheese, etc.) sometimes you may need to get extra amount of protein. For example, if you are into body building you need to build muscle mass and lose fat to get the kind of body you are looking for. Also, you may need to add extra protein to your diet and, in this case, protein isolates are an easy way to get a lot of protein with little amount of food ingested.

Types of Protein Isolates

There are three available forms of products rich in protein: Hydrolysates, Concentrates and Isolates. Protein hydrolysates are protein rich products in which the protein has been partially broken is smaller pieces. Because of this, they are easily digested (in fact, they are pre-digested with enzymes). Protein concentrates have 29 to 89% protein but have higher concentrations of fat and carbohydrates. Protein isolates are higher in protein content 90-95% and have the lowest amount on non-protein compounds.

Examples of Protein Isolates

Any food product could be used to make a protein isolate. Meat, fish, milk, and vegetable protein isolates are possible. However, two products are worth mentioning here because of the broad availability of them in supermarkets and in health food stores: whey protein isolate and soy protein isolate.

Whey Protein Isolate (WPI)

During cheese manufacturing, milk is precipitated (coagulates) by means of enzymes (rennin), acidification or heating. The precipitate originates the cheese after processing. The liquid remaining from this process is called whey. The whey is removed from cheese manufacturing and used to make whey protein isolate. WPI is a mix of beta-lactoglobulin (~65%), alpha-lactoalbumin (~25%), and serum albumin (~8%). Globulins type of proteins are easily digested by the human digestive system.

Soy Protein Isolate (SPI)

Soy protein isolate is derived from the soy legume. The seed of soy stores protein to be used during germination. This protein is extracted from soy beans and purified as to get commercial SPI. During soybean processing (to extract oil) a flour remain which is rich in proteins. So, defatted soy flour is used to make SPI after removing all non-protein materials such as fats and carbohydrates. SPI may have up to 92% protein content on a dry basis. SPI is a complete protein. It has all essential amino acids needed for growth and it is equal in quality to the protein in meat, milk and eggs. For this reason is highly preferred by vegetarians.

There are other types of isolates that you can find in the market: pea protein isolates, milk protein isolates, wheat protein isolates, etc.

Sources:

Onwulata CI, Huth PJ (2008). Whey processing, functionality and health benefits. Ames, Blackwell Pub. IFT Press

Liu, K. (1997) . Soybeans : Chemistry, Technology, and Utilization. Springer.