Effects of temperature and pH on the enzymatic degradation of parishins from Gastrodia elata

This study investigated effects of temperature, pH, and time on enzymatic degradation of parishins in three systems (simple parishin A, complex G. elata matrices and verification systems). The regulation mechanisms governing the enzymatic changes in seven phenolics (parishins A, B, C, E, gastrodin, p -hydroxybenzylalcohol and p -hydroxybenzaldehyde) were elucidated. By increasing temperature and pH, the carboxylesterase activity overall presented parabolic trends, with peaking at 50 °C and pH 6, respectively. Phenolic variation at 40 °C–60 °C and pH 4–6 was dominated by enzymolysis, while parishin degradation was characterized by potential joint effect of “enzymatic + thermal/alkaline hydrolysis” at 70 °C–90 ℃ and pH 7–8. Verification with 0.01%–1% carboxylesterase revealed that carboxylesterase could drive phenolic metabolism by hydrolyzing ester-linkages. By regulating concentration and time of carboxylesterase at 50 ℃ and pH 6, preliminary directional modulation of phenolic profiles can be realized to produce diverse processed G. elata products enriched with specific target phenolic components. This study provided a theoretical basis for the oriented regulation of bioactives in G. elata .