Chemical oxidative phenolic browning reactions in a sinapic acid model system

In order to determine the influence factor of sinapic acid chemical oxidation, so as to provide the basis for better control of fruits and vegetables browning, sinapic acid chemical oxidation simulation system was established. The sinapic acid concentration and browning degree were investigated at 315 nm and 420 nm by ultraviolet visible spectrophotometer.Chemical oxidation of sinapic acid accords with First order reaction kinetics model by kinetic fitting. The rate of chemical oxidation of sinapic acid was maximum at p H10.0 ( 5.38 h^-1) .The results of orthogonal test showed that the effect of temperature at 0.05 level on the chemical oxidative browning of sinapinic acid was significant and the effect of p H at 0.1 level on the chemical oxidative browning of sinapic acid was significant. The effect of concentration of sinapic acid at 0.1 level on the chemical oxidative browning of sinapic acid was not significant.Sinapic acid was more prone to chemical oxidation at p H10.0 than p H3.7and p H7.0 and at 90 ℃ than 40 ℃ and 25 ℃.Sinapic acid is more susceptible to oxidative browning in high temperature and alkaline environment.For this feature, in order to as far as possible to avoid the occurrence of browning of fruits and vegetables, high temperature and alkali processing operations should be avoided.