Milk and its properties as an object of separation

Abstract

Separation is one the essential processes in dairy products processing. In the article, properties of milk that are determining the value of milk separability as a disperse system, namely the density of plasma and disperse particles, the viscosity of plasma and disperse structure of disperse phases are considered. Correlation of density and viscosity of the milk components with a temperature is reviewed. Distribution of fat globules in milk, milk-fat globule membrane (MFGM) thickness and influence of mechanical impact (pump-ing, mixing, centrifugal purification) on disperse structure of fat in milk are also reviewed. Milk is considered as a low-concentration finely combined (emulsion + suspension) dispersion system. As the separation remains one of the most used method of clarification and purification of milk, it is necessary to know curtain properties of milk components. The efficiency of milk separation process relies on knowledge of such properties, such density and viscosity of milk plasma, density of milk fat globules, thickness of milk fat globule membrane, distribution of fat globules by the size. The ways of calculation of these properties are presented. In addition, mechanical impact on milk properties in the course of its receiving and processing is reviewed. Calculation of separability of disperse systems ‘milk fat globule-milk plasma’ and ‘milk mechanical impurities – milk plasma’ is presented. The separability values of milk fat globules and milk mechanical impurities in dependence on milk temperature, in the range 30 – 70 °C and 5 – 75 °C respectively, are presented in the article and could be used in calculations of separators-clarifiers and separators-pu-rifiers. The properties of separators sludge, which is created in course of whole or skim milk purification, and the sizes of its particles are still to be discovered