Problems related to lactose crystallization

Dried milk and whey. Lactose is the major component of dried milk products whole-milk powder, skim-milk powder and whey powder contain c. 30, 50 and 70% lactose, respectively. Protein, fat and air are dispersed in a continuous phase of amorphous solid lactose. Consequently, the behaviour of lactose has a major impact on the properties of dried milk products. 

Concentrated lactose syrup LACTOSE GLASS (Non-crystalline) 

The state of lactose has a major effect on the properties of spray-dried whey powder manufactured by conventional methods, i.e. preheating, condensing to about 50% total solids and drying to less than 4% water. The powder is dusty and very hygroscopic, and when exposed to ambient air it 

Problems arising from the crystallization of lactose in milk and whey powders may also be avoided or controlled by pre-crystallizing the lactose. Essentially, this involves adding finely divided lactose powder which acts as nuclei on which the supersaturated lactose crystallizes. Addition of 0.5 kg of finely ground lactose to the amount of concentrated product (whole milk, skim milk or whey) containing 1 tonne of lactose will induce the formation of c. 10 crystals ml about 95% of which will have dimensions less than 10 jum and 100% less than 15 m, i.e. too small to cause textural defects. 

Thermoplasticity of lactose. Unless certain precautions are taken during the drying of whey or other solutions containing high concentrations of lactose, the hot, semi-dry powder may adhere to the metal surfaces of the dryer, forming deposits. This phenomenon is referred to as thermoplasticity. The principal factors influencing the temperature at which thermoplasticity occurs ( sticking temperature ) are the concentrations of lactic acid, amorphous lactose and moisture in the whey powder. 

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