Abstract: Immobilized polyphenol oxidases (IPPO) was applied for the synthesis of theaflavins using tea catechins as substrates. A Response Surface Methodological (RSM) study was conducted using a five-level, five-variable, central composite rotation design (CCRD) to select the optimum catalysis conditions for theaflavin transformation from tea polyphenol through immobilized enzyme membrane. Five important variables were considered, namely, incubation duration, enzyme/substrate ratio (E/S, Activity Units/ml-AU/ml), aeration volume, concentration of tea polyphenols, and the pH value of the reaction system. The highest theaflavins concentration of 0.766βmg/ml was predicted under the conditions as with 49βmin for the incubation duration, 128.7 for E/S ratio, 23.81βml/min ventilation for air volume, 5.95βmg/ml for catechins concentration, and pH 4.3. The measured theaflavins concentration was 0.754±0.017βmg/ml under the same condition, which suggested that the prediction model was practical and the selected conditions were reasonable.

Key words: Response surface method, Catechin, Theaflavins, Immobilized enzyme membrane, Polyphenol oxidases