Kinetics of Lactose Crystallization

Abstract

The effects of certain variables on α-lactose crystallization were examined. The temperature for optimum crystallization rate varied with the initial supersaturation. Crystallization rate was not directly proportional to seed crystal surface area, probably because of false graining or because mutarotation has a limiting effect on rate as surface area is increased. When the position of the isomer balance (relative proportions of α- and β-lactose present in solution during crystallization) was studied, mutarotation rate was found to determine crystallization rate under conditions of high surfaee area. In the latter stages, however, crystallization rate itself was limiting, rather than mutarotation. Low pH's (about pH 1) increased crystallization rate greatly as a result of increased mutarotation rate, increased rate of orientation of lactose molecules into the crystal, or both. Only in certain instances did the crystallization of lactose follow first-order diffusion kinetics. Rate of crystallization increased with some power of supersaturation greater than one. © 1968, American Dairy Science Association. All rights reserved.