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Developing a new production process for high-porosity lactose particles with high degrees of crystallinity

Ebrahimi, Amirali, Saffari, Morteza, Langrish, Timothy
Powder technology 2015 v.272 pp. 45-53
citric acid, crystal structure, ethanol, lactose, porosity, powders, scanning electron microscopes, spray drying, stickiness, surface area, temperature, texture, whey protein isolate
Highly porous lactose with a high degree of crystallinity has been prepared by a new production process. A solution containing lactose, whey protein isolate, and citric acid as a template has been dried using a Buchi-B290 mini spray dryer with an inlet temperature of 180°C. Samples have been treated with ethanol to dissolve the citric acid and simultaneously increase the crystallinity of the spray-dried lactose. The resulting powder structure is a lactose network with significant porosity and a high surface area of 28.9±0.7m²/g, while maintaining the strong stability of a highly crystalline powder. It has been demonstrated that textural properties, such as surface area and pore volume of the resultant lactose, can be tuned by varying the concentration of citric acid. Increasing the citric acid content decreases the surface area of the ethanol-washed powders beyond a citric acid concentration of 2%, which may be connected with the decrease in the amount of incorporated citric acid molecules due to the increase in the degree of crystallinity for the spray-dried lactose powders. The scanning electron microscope micrographs were consistent with the results of BET surface area measurements. It has been also found that adding citric acid to the lactose and to the lactose/WPI solutions decreases the yield of the spray-drying process due to stickiness. The results allow excipients to be produced with significant concentrations of surface asperities and large specific surface areas for use in direct compression tableting techniques.