Surface characterisation of freeze-dried protein/carbohydrate mixtures

Differences in the physical state and thermal behavior of spray-dried and freeze-dried lactose and lactose/protein mixtures

“…Freeze-dried amorphous lactose/WPI, lactose/Na-caseinate, and lactose/gelatin resembled broken glass or flake-like structure similar to that of lactose. Similar type of structure was also observed by Millqvist-Fureby et al (1999) in other freeze-dried carbohydrate/protein mixtures. A significant change in particle structure was observed when lactose/protein mixtures were stored at RVP !…”

“…1). Millqvist-Fureby, Malmsten, and Bergenståhl (1999) showed that flake-like morphology was obtained in freeze-dried amorphous lactose and long rod-like structure in crystalline lactose. These observations agreed well with the present study.…”

An Aqueous Polymer Two-Phase System as Carrier in the Spray-Drying of Biological Material

“…78,000) is 71.7 mN/m (28), which also indicates that PVP would compete more favorably for the air/water interface in competitive adsorption. As shown previously for the spray-drying of protein/carbohydrate mixtures (19,20,29), the surface of the spray-droplet is preserved during drying and is thus reflected in the surface of the dried powder. It has also been shown for competitive adsorption in the spray-drying process that the more surface-active component tends to dominate the surface (29,30).…”

Evidence of partial unfolding of proteins at the ice/freeze-concentrate interface by infrared microscopy

“…There is a small but growing body of literature supporting the idea that loss of protein integrity during freezing is, at least in part, an interfacial phenomenon involving unfolding of protein molecules at the ice/freeze-concentrate interface. [3][4][5][6][7][8] The goal of this study is to attempt to gain a better understanding of freezing-induced damage to proteins as an interfacial phenomenon by measuring protein secondary structure in different microenvironments in a partially frozen system. A recent study reported interfacing a commercially available freeze-drying microscope stage with an infrared microscope for in situ measurement of protein secondary structure in the liquid, frozen, and freeze-dried states.…”