title: Crystallization and X-ray diffraction of spray-dried and freeze-dried amorphous lactose.
abstract: Crystallization of spray-dried and freeze-dried amorphous lactose over different relative vapor pressures (RVP) and storage times was studied. Crystallization was observed from increasing peak intensities in X-ray diffraction patterns. Lactose was crystallized in the samples stored at RVP of 44.1% and above in both types of dehydrated powders. The rate of crystallization increased with increasing RVP and storage time. Similar crystallization behavior of both spray-dried and freeze-dried lactose was observed. Lactose crystallized as alpha-lactose monohydrate, anhydrous beta-lactose, and the anhydrous form of alpha- and beta-lactose in a molar ratio of 5:3 and 4:1 in both spray-dried and freeze-dried forms. Peak intensities of X-ray diffraction patterns for anhydrous beta-lactose were decreased, and for alpha-lactose monohydrate increased with increasing storage RVP and time. The crystallization data were successfully modeled using Avrami equation at RVP of 54.5% and above. The crystallization data obtained is helpful in understanding and predicting storage stability of lactose-containing food and pharmaceutical products.
authors.affiliation: Department of Food and Nutritional Sciences, University College Cork, Cork, Ireland.
authors.forename: Md Kamrul
authors.initials: MK
authors.lastname: Haque
authors.forename: Yrjö H
authors.initials: YH
authors.lastname: Roos
mesh_terms: D003460:Crystallization; D005612:Freeze Drying; D007700:Kinetics; D007785:Lactose / Q000737:chemistry*; D014961:X-Ray Diffraction
chemical_list: D007785:Lactose