Crystallisation kinetics of lactose in the absence of lactose phosphate

This paper studies three approaches based on experimental data to define the constants of a power law function describing the crystallisation kinetics of pure lactose: growth rate(G) = kg *(driving force)n . Seeded-batch crystallisations of lactose were conducted at different temperatures and median sizes of seeds. The syrup fed to each batch was prepared from crystals free of lactose phosphate, produced by a patented process. The first two approaches used a single curve fitting technique. The third approach employed a nonlinear least squares dynamic optimisation technique. The value of n was found to be constant and equal to 2.8 but kg increased with increasing temperature and decreasing seed size. The results indicated that the kinetics differed for a pure feed compared to a commercial feed. The new relationship will be used as a reference for ongoing crystallisation studies with different quantities of lactose phosphate added to the pure lactose syrup.