Non-enzymatic browning and the kinetic model of 5-hydroxymethylfurfural formation in residual solution of vinegar soaked-soybean

Non-enzymatic browning of vinegar soaked-soybean residual solution was investigated using a model solution. A glycine-fructose-gallic acid model system was proposed by analyzing reducing sugars, amino acids, total phenolics, and pH value of the vinegar soaked-soybean residual solution. Based on the proposed model, the kinetics of 5-hydroxymethylfurfural (5-HMF) formation was also studied. The results showed that Maillard reaction and sugar pyrolysis might be the accurate mechanisms of non-enzymatic browning in vinegar soaked-soybean residual solution. The formation of 5-HMF in the model solution exhibited characteristics of the first-order kinetic model at temperature from 60 to 140 °C. The frequency constant k f was 450.65 /h, and the apparent activation energy E a was 20.15 kJ/mol. Acetic acid, Fe 2+ , and Fe 3+ significantly enhanced the browning rate and 5-HMF formation; whereas Ca 2+ , Mg 2+ , Na + , glucose oxidase, and H 2 O 2 inhibited the browning rate.