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A RESEARCH ON KINETIC MODELLING ON EXTRACTION OF TOTAL POLYPHENOL FROM OLD TEA LEAVES

In this study, kinetic modeling by investigating the effect of material sizes, water/material ratios and temperatures was conducted. Polyphenol concentration increased with reducing size, increasing the water/material ratio and temperature. The results showed that under extraction conditions such as the material size of 0.3 mm, the water/sample ratio of 15/1, the extracting temperature of 60 o C, and extracting time of 40 minutes, the polyphenol content obtained was of 77.33 mgGAE.g -1 with value of initial extraction rate reached 50.90 mgGAE.g -1 .min -1 and the activation energy was determined as 16.162 kJ/mol. Polyphenol extraction dynamic model from the old tea leaves relied on the assumption of the quadratic function has been successfully constructed to predict the extraction process and mechanism. Based on the kinetic equation, extraction parameters, including Ce extraction ability, extraction velocity, extraction constant k, and activation energy E can be determined, facilitated optimization, designed, simulated and controlled significant industrial projects.