Drying of Milk and Milk Products

Abstract

Milk is extremely perishable, yet for a number of reasons it is desirable to preserve it for later consumption. Today, drying is the most important method of preservation. The advantage is that using modern techniques, it is possible to convert the milk to powder without any loss in nutritive value, i.e. milk made from powder has the same food value as fresh milk. The disadvantage is that drying consumes a lot of energy; in fact, no other process in the dairy industry has a higher energy demand per tonne of finished product. This is due to the fact that approximately 90 per cent of milk is water, and all the water has to be removed by evaporation using heat. Modern membrane techniques make it possible to remove some of the water mechanically, without heat, but this method has limitations so it is not widely used in practice. Nevertheless, the sharp increase in the cost of energy has caused significant developments in process and equipment, making it possible today to convert milk into powder with an energy consumption per tonne of finished product approximately half that required years ago.