An in vitro model fermentation system, containing tea catechins and crude pear polyphenol oxidase from pear fruits has been used to determine the effect of tea catechin mixtures of different proportions & physico-chemical conditions on the formation of theaflavin. The optimum condition of theaflavins is 30℃ and The pH optima for theaflavin formation were 5.5. The tea catechins(EGC>200 mg/g, EGCG>200 mg/g, total catechins>500 mg/g) concentration is 5 mg/ml and the concentration of enzyme is 75 ml/1 000 mg. p...