Bovine Serum Albumin-Sugar Conjugates through the Maillard Reaction: Effects on Interfacial Behavior and Emulsifying Ability

Abstract

Bovine serum albumin (BSA) was employed as a model protein emulsifier to conjugate with aldohexose (D-glucose (Glc) or D-allose (All)) and sugar fatty acid ester (6-O-octanoyl-D-glucose (GlcC8)) through the Maillard reaction. It was found during the reaction that rate of decrease of free amino groups in BSA was almost the same for the BSA-sugar mixtures whereas browning and protein aggregation developed in the following order: Glc < All < GlcC8. It was thought that the rate of degradation of the Amadori compound could have been influenced by the OH-group stereochemistry at the C3 position of aldohexose, while denaturation of BSA by GlcC8 enhanced the browning and protein aggregation. To understand the emulsifying ability of the BSA-sugar conjugates, hexadecane-water interfacial tension and the oil droplet size of emulsions prepared by homogenizing hexadecane and aqueous solution of the conjugates were examined. BSA-GlcC8 showed greater improvement in interfacial and emulsifying activity than did BSA-Glc and -All. However, no improvement in emulsion stability was observed for any of the BSA-sugar conjugates, suggesting the weakness of the film formed at the oil droplet interface.