Kinetics of L-ascorbic acid degradation and non-enzymatic browning development in hot-compressed water

The effect of reaction conditions, which comprised the reaction temperature (150-190 degrees C), processing time (0.50, 0.75, 1.00, 1.25, 1.50, 2.00, and 2.50 h), pH (5.0, 7.0, and 9.5), and concentration (0.03-0.07 mol/L) of L-ascorbic acid (ASA), on the degradation of ASA was investigated in hot-compressed water (HCW). The degradation kinetics of ASA and generation kinetics of browning products (BPs) were studied. The results showed that ASA degradation conformed to the pseudo-first-order kinetics, and the formation of BPs was closely related to the concentration of H3O+ in HCW. The acidic condition (pH = 5.0) and lower concentration of ASA (0.03 mol/L) were more favorable for ASA degradation. In HCW, the average apparent activation energy (Ea) of ASA was 15.77, 31.70, and 47.53 kJ/mol at pH 5.0, 7.0, and 9.5, respectively. The possible degradation mechanisms of ASA and the generation of BPs in HCW were proposed based on the experimental results.

Automated summary

The study investigated the degradation of L-ascorbic acid (ASA) and the generation of browning products (BPs) in hot-compressed water (HCW) by adjusting the reaction conditions. It was found that ASA degradation followed pseudo-first-order kinetics and the formation of BPs was closely related to the concentration of H3O+ in HCW. The acidic condition (pH=5.0) and lower concentration of ASA (0.03 mol/L) were found to be more favorable for ASA degradation.