Carbohydrate and Protein in Milk

Carbohydrate in Milk

Lactose, or milk sugar, is the primary carbohydrate found in milk – 12 grams per 8-ounce cup. When bacteria in milk metabolize lactose, lactic acid is produced. The flavor of cheese and fermented milk products such as yogurt and sour cream is, in part, derived from the lactic acid. Lactose tends to be less soluble than sucrose, which may cause it to crystallize into limps in nonfat dried milk and to produce a sandy texture in ice cream. Some people suffer from lactose intolerance caused by a deficiency of the lactase enzyme, which is required to digest lactose. For people with this problem, fermented milk products are usually more easily digested.

Protein in Milk

The protein in milk is a complete protein; that is, it contains all the essential amino acids in adequate quantities necessary to support growth and the maintenance of life. A cup of milk contains approximately 8 grams of protein. Two servings of milk or milk products a day provide almost half the protein recommended for a healthy adult woman, and one-third that for a man.

The two predominant types of protein found in milk are casein and whey. Casein accounts for almost 80 percent of the protein in milk, while whey proteins constitute about 18 percent. Whey proteins consist primarily of lactalbumin and lactoglobulin. The nutritious whey proteins can be isolated by putting the whey through an ultra filtration process. These whey protein concentrates are extensively used by the food industry as emulsifiers and as foaming and gelling agents. Adding milk proteins to other foods generally improves their texture, mouthfeel, moisture retention, and flavor.