Types of Casein

Casein is a protein that makes up roughly 80 percent of the protein in cow's milk. It digests slowly and contains all of the essential amino acids people must obtain from their diet. Casein makers use centrifugal force to separate milk into butterfat for cream and butter, and skim milk for casein. They add enzymes and other natural substances to the skim milk to develop specific caseins.

Casein's Properties

• Though casein and its derivatives come in several forms, all types of the protein have the same properties. Caseins are not water-soluble, and must be paired with an alkaline solution such as bean protein before use. Caseins' ability to absorb water helps the proteins thicken soups or improve the texture of baked goods. And caseins all have the eight essential amino acids that the human body can't make on its own, including tryptophan and phenylalanine. That acid profile makes casein a nutritious protein.

Rennet

• Traditional rennet is casein made from combining skim milk with milk-clotting enzymes found in milk-fed calves' or lambs' stomachs. Home cheese-makers use rennet casein in liquid or powder forms to thicken and curdle milk into cheeses. Commercial cheese-makers use genetically modified microbial rennet in their production process. Vegetable rennet extracted from mold is used to make vegetarian cheeses.

Acid Caseins

• These caseins use acids as thickening agents for the protein's skim milk base. Lactic acid, hydrochloric acid and sulphuric acid are the primary thickeners in acid caseins. Food makers add caseins to processed products as a nutritional supplement or to thicken or otherwise change a food's physical properties. Consumers will find acid caseins in coffee creamers, yogurt, ice cream, instant breakfast cereals, nutrition bars, pharmaceuticals, soups, whipped toppings and sport drinks. Industrial manufacturers add nonfood-grade acid caseins to adhesives and water-based paints.

Casein Proteins for Bodybuilding

• Because casein is a slow-release protein, athletes and bodybuilders say it's an ideal supplement for strength training and muscle development. Casein-based muscle supplements mix the protein with alkaline solutions to create water-soluble derivatives called caseinates. The three derivatives in muscle-building formulas are calcium caseinate, micellar casein and milk protein isolate. Trainers advise clients to take caseinates not only before workouts, but before sleep. Casein sustains the body's protein levels through the night, reducing muscle wasting from inactivity.