SORBATE DESTRUCTION AND NONENZYMATIC BROWNING IN MODEL AQUEOUS SYSTEMS

The effect of system composition on sorbate destruction and sensory da mage due to non-enzymatic browning was studied in aqueous model system s with a water activity (a(w)) of 0.91 and a pH of 5.0-6.0. The rate c onstants of sorbate destruction could be described by first order kine tics and those from non-enzymatic browning by zero order kinetics. Bot h reactions were found to be related not only to temperature and pH bu t also to the humectants (NaCl, glycerol) used to depress a(w). A high er preservative retention and a smaller amount of browning was produce d by the use of a mixture of 35.0 g/kg of NaCl and 220.0 g/kg of glyce rol as a humectant instead of one of them alone, citric acid instead o f phosphoric acid as the acidifying agent, and glass flasks instead of polyethylene containers. The non-enzymatic browning reactions were gr eatly influenced by sorbic acid destruction. The inclusion of glycine was responsible for the enhanced sorbate destruction and browning deve lopment.