CRYSTALLISATION RATE OF LACTOSE IN MILK SUGAR PRODUCTION

LJHANN

Abstract

From the analysis of literature it follows that further improvement of lactose crystallisation is necessary, which should be carried out taking into account theoretical justifications. One of the main parameters necessary for the development of a rational mode of crystallisate cooling in the production of milk sugar is the crystallisation rate. Therefore, the aim of the work was to experimentally determine the crystallisation rate of lactose in molasses obtained under conditions of membrane purification of feedstock.The object of research was a model crystallisate obtained from molasses and milk sugar crystals.The studies were carried out in the temperature range t=10-80°C with an interval of 10 degrees centigrade. During the studies at intervals of 1, 2 and 6 hours the mass fraction of solids and lactose, as well as the average linear size of crystals were measured. The benignity of the intercrystalline solution was Db=58-83%. From the data obtained on the amount of crystallised lactose, crystal surface area and time interval, the crystallisation rate was calculated. The activation energy of the crystallisation process was 59.387 kJ/mol.The dependence of crystallisation rate on temperature has been found to be exponential in nature. The obtained value of activation energy indicates that the complex of non-sugars present in molasses prevents lactose crystallisation. The established regularity should be taken into account when developing the crystallisate cooling regime in milk sugar production.