Whey is the serum or liquid part of the milk that is separated from the curd when making cheese. Whey is used in a wide variety of food industries as it has excellent nutritional properties. Whey is also used as a 'functional' food in health, slimming and clinical foods.
Due in part to increased environmental concerns about disposal, the traditional outlets for whey, such as returning it to the milk suppliers for cattle or pig feed, or use as a fertilizer, or simply dumping it into the rivers or drains, no longer viable or too expensive. In the recent years it has therefore been necessary to find alternative uses for whey which had always been regarded as a waste product. However, the why dry matter contains components of high nutritive value and new techniques have made it possible to extract and utilize these.
Fresh whey from conventional cheese production is approximately: 94% water, less than 1% protein, 4.5% lactose, less than 1% ash and less than 1% fat.