Emulsifying properties of bovine serum albumin-galactomannan conjugates.

Bovine serum albumin (BSA)-galactomannan conjugates were prepared through the Maillard reaction. To 1 mol of BSA was bound 2.5-7 mol of galactomannan. Conjugates could be grouped into two fractions, on the basis of the weight-average molar mass measured with a multiangle laser light-scattering detector, the main one with 220 000-250 000 Da and the other one with a very small amount of aggregates over 1 000 000 Da. Spectroscopic analysis suggested that the surface of the conjugate was covered with galactomannan and the conformation of the hydrophobic interior and the secondary structure were not significantly changed. The emulsifying activity index of the conjugates increased greatly as compared with that of BSA alone. All conjugates showed better stability than BSA, presumably due to the physical protection introduced by the viscoelastic galactomannan layer. The average particle sizes of the emulsions were similar. The interfacial properties of the BSA-galactomannan conjugates were improved, possibly due to the reduced hydrophobic interaction between the droplets and the viscoelastic interfacial properties of galactomannan.