Rennet casein - functions and properties

What is rennet casein?

Rennet casein is a protein product that is created when rennet is added to pasteurized skim milk causing coagulation and precipitation of the casein protein. The general composition of is 80.5 percent protein, 0.5 percent lactose, 8 percent ash, 1 percent fat, and 10 percent moisture, all of which vary slightly by manufacturer. Rennet is a set of proteolytic enzymes that produced in the stomach lining of ruminant animals, but plant and microbially based rennet is commonly used in modern times. Rennet contains lipases, pepsins and most importantly chymosin that coagulates the casein proteins in milk.

How is rennet casein made?

Skim milk that has been pasteurized is heated and coagulated by rennet enzymes leading to precipitation of the casein protein. Once the milk has coagulated, the whey is drained off and the curds are washed thoroughly with water. The casein curds are pressed, ground down thoroughly, and dried with heat which evaporates out the remainder of the water left in the curds to form a powder.

What is rennet casein used for?

The primary use for rennet casein is as an additive in processed cheese and cheese analogues. Rennet casein is used to improve the texture, the stretch, and the ability of melting in processed cheeses. Through the addition of rennet casein into a processed cheese, the protein content can be increased, and the fat and sodium levels can be decreased. The addition of rennet casein can also aide in extending shelf life through its water retention properties. The same water retention properties of rennet casein that are used in the food products are utilized in industry in other non-food related items like paint, paper, and plastics.

What does rennet casein taste like?

Rennet casein overall has a very bland flavor profile in its most perfect form. Rennet casein more commonly has a tortilla and animal note with a sour taste. Towards the end of the rennet caseins’ shelf-life, the product starts to have stronger cardboard and paper notes. The mouthfeel is somewhat gritty as rennet casein is generally not soluble in water unless further treatments are added to modify the product. Rennet casein can have more aroma and some brothy or barny off flavors than other milk powders.

What are the functional properties of rennet casein?

The benefits of rennet casein are numerous in terms of processed cheese production. In a processed cheese, the addition of rennet casein aides to increase the texture, stretch and melting capabilities of the product. Rennet casein is used as an additive to improve nutritional benefits of a food by increasing the protein content. Rennet casein can also help to reduce the sodium and fat content of a food by reducing the use of additional emulsifying salts in processed cheese production. In industrial applications, rennet casein helps form films that can help to create strength in the product.