Kinetics of degradation of sorbic acid in aqueous glycerol solutions

Degradation of sorbic acid in aqueous glycerol solutions at pH 4·0 over the a_w range 0·71–1·00 and the temperature range 40°–60°C was found to follow first-order reaction kinetics and to conform to the Arrhenius equation. Activation energy values obtained were 5·8 kcal mol^?1 and 7·8 kcal mol^?1 for systems at 0·80 a_w with and without added Co⁺⁺, respectively. The rate of sorbic acid degradation was observed to increase with decreasing a_w (i.e. increasing glycerol concentration). The presence of added Co⁺⁺ decreased the rate of sorbic acid breakdown at any particular a_w or temperature. Browning of sorbate solutions during storage was markedly inhibited by Co⁺⁺.