Abstract:

Glucosamine sulfate samples were heated at 60, 70, 75 and 80 ℃ for 10 h, respectively. The changes in browning index (absorbance at 420 nm), contents of 5-hydroxymethyfurfural (5-HMF) and glucosamine sulfate and pH value were determined to estimate the extent of nonenzymatic browning during the heating process. Then zero-order kinetics was applied to describe the results. It was found that with the increase of heating temperature and time, 5-HMF content and browning index increase, while glucosamine sulfate content and pH value decrease. The nonenzymatic browning reactions of glucosamine sulfate accord with zero-order kinetics model, and the activation energies of changes of browning index and 5-HMF content are 85.127 kJ/mol and 136.973 kJ/mol, respectively. Moreover, NaHSO3 shows certain inhibitory effects against nonenzymatic browning of glucosamine sulfate.

Key words: glucosamine sulfate, nonenzymatic browning, 5-hydroxymethyfurfura (5-HMF)