Effect of glycerol on water sorption of bovine gelatin films in the glassy state

The addition of low molecular weight compounds to a biopolymer in the glassy state can generate changes in macrostructural properties of the matrix. This work studied the effect of glycerol on water sorption properties of gelatin films in the glassy state. Bovine gelatin-glycerol (0-10% dry basis, db) films were equilibrated to moisture contents (MC) in the range of 5 - 30% (db). Results show that the addition of glycerol generated differences in sorption behaviour by the decreasing of sorption parameters (GAB, BET and Freundlich), indicating complex glycerol-matrix interactions. Gas pycnometry showed a densification of the matrix suggesting a reduction in sorption site availability when glycerol content increased.