Influencing lactose crystallization in whey powder processing

Introduction: The degree of crystallization of whey determines its process behaviour, since amorphous whey for example sticks to spray dryer walls. Further, whey composition affects the degree of crystallization and sesequently powder functionality. In this study, the effect of different seeding lactose crystals at different incubation temperatures were examined. Additionally, the impact of riboflavin on lactose crystallization was investigated.
Methods: Whey of the Emmentaler production was concentrated by vacuum evaporation. Crystallization was performed at laboratory scale, followed by spray drying done with the Büchi Mini Spray dryer B-290. The degree of crystallinity in the concentrate was determined before spray drying and particle size, water activity, and solubility of the powder analyzed.
Results: Without seeding, the pre-crystallization of lactose was significantly delayed. Seeding lactoses (GranuLac®70 and GranuLac®400) with different crystal sizes did not show a significant difference in the degree of crystallization. Riboflavin hindered crystallization. Crystallization at 15°C or 10°C did only lead to small changes of crystallization yield. Powder functionality parameters like solubility are affected by the different treatments.
Conclusion: The crystallization of lactose in whey is affected by riboflavin, temperature and the type of seeding lactose. We established a stable process for whey powder processing that can be used to determine effects of whey variability.