The effect of chitosan hydrogen bonding on lactose crystallinity during spray drying

The effect of chitosan on the crystallization behavior of lactose has been studied during the spray drying of lactose/chitosan solutions. Solutions with different ratios of lactose and chitosan have been spray dried at an inlet temperature of 160 °C using a laboratory-scale spray dryer. Water-induced crystallization, X-ray diffraction analysis and differential scanning calorimetry have been used to study the crystallinity of the spray-dried lactose/chitosan powders. Results show that, despite the ability of chitosan to retain moisture for a longer time during spray drying, the spray-dried powders were in the amorphous form. Moisture-induced crystallization and differential scanning calorimetry results suggest that the presence of chitosan delays lactose crystallization. This finding may be due to the high glass-transition temperature of chitosan, despite its ability to hydrogen bond with water, which was suggested previously by other researchers to be a reason for crystallizing lactose during spray drying in the presence of polyethylene glycol.