Cooling and Evaporative Crystallization of α-D-Galactose from a Highly Viscous Industrial Side Stream

An industrial side stream containing mainly glucose and galactose was used to crystallize α-D-galactose. The dynamic viscosity of samples containing galactose and glucose solutions was measured and compared with pure glucose and galactose solutions. Various crystallization conditions were investigated in terms of temperature range and batch times in cooling crystallization and their influence on the product crystal properties. The obtained results were compared with the results of evaporative crystallization. Several characterization methods were used for studying crystal size and shape, crystal structure, and purity. The overall crystallization time of α-D-galactose was shortened by cooling crystallization based on stepwise temperature decrease and the desired crystal properties were achieved.