Continuous lactose recovery from acid whey by mixed suspension mixed product removal (MSMPR) crystallizer in the presence of impurities

The continuous crystallization approach provides the opportunity to intensify production and improve the quality of crystals manufacturing. This study examined the effect of impurities on lactose crystallization in the continuous mixed suspension mixed product removal (MSMPR) crystallizer. Two impurities usually present in acid whey, protein and lactic acid, were examined. The continuous process was evaluated based on the time required to reach a steady state operation, particle size distribution (PSD), purity, and yield. Impurities increased the time for the continuous system to achieve a steady state condition. This effect was more pronounced in the presence of protein (>13 residence time). In the acidic environment, lactose crystals tended to promote caking and agglomeration during the filtration process, resulting in the formation of larger crystals and a wider PSD. The protein incorporation in the continuous process was 1.5 times higher than in the batch process due to the in-efficiency of the filtration stage caused by the aggregated denatured protein particles, which entrapped the mother liquor between the void area of the agglomerated crystals. Understanding impurity effects on lactose crystals in continuous crystallization can be used as a fundamental study to intensify the process and improve the quality of the crystals.