文档介绍：Abstract
Epigallocatechin gallate (EGCG) is the most important catechin in green tea which
has many health benefits. But EGCG is very unstable and can be easy influenced by
various factors like temperature, pH and metal ions in the process of machining and
storing of tea occurred degradation and epimerization will change the
former biological activity of EGCG and also exert negative influence on the quality of tea
beverage. The effect of temperature on EGCG was studied and the chemical ics of
various EGCG reactions were effects of L-cys and L-Vc on the thermal
reaction of EGCG were also discussed. The pounds produced form the thermal
reaction of EGCG adding L-cys were purified and analyzed. Following conclusions were
obtained:
1 This degradation, epimerization, de-gallateand acid and oxidation reaction of EGCG
under different heat treatment were studied, and the related ic predicting models
were established by using Arrhenius results showed that Ea (activation
energy) and A (frequency factor) of the degradation, epimerization, de-gallate acid and
oxidation reaction of EGCG in predicting model were and ×104,
and ×1012, and ×1010, kJ/mol and ×1010,
respectively. It showed that the degradation of EGCG could be vulnerable occured and
the epimerization of EGCG was difficult, the de-gallate acid and oxidation reaction of
EGCG were close. The relative error between the model predicted value and actual value
was less than 13%. Therefore, the heating variation of EGCG could be predicted by
Arrhenius equation.
2 By adding L-cys and L-Vc to control the oxidation of EGCG, the experience found
that L-cys and L-Vc was not consistent. L-cys, promoted the epimerization while
inhibiting oxidation, however, L-Vc also inhibited the epimerization while inhibiting
oxidation. After adding L-cys and L-Vc with equal molar concentration (0