The purpose of this study was to determine the optimum re-extraction conditions of ethanol from catechin in Korean green tea (Camellia sinensis L.) using response surface methodology (RSM). The experiments were carried out according to a five level and two variable central composite design (CCD). The two independent variables were solvent ratio to sample content (1, 4, 7, 10, 13 mL/g) and extraction temperature (-20, -10, 0, 10, 20℃) on the dependent variables including yield, epigallocatechin (EGC), epicathchin (EC), epigallocatechingallate (EGCG), epicatechingallate (ECG), total catechin and caffeine. ANOVA results showed that Coefficients of determination (R 2 ) of estimated models for dependent variables were ranged from 0.9054~0.9778, while R 2 of caffeine were estimated 0.8770. The optimum ranges for the maximized extraction including yield, EGC, EC, EGCG, ECG, caffeine and total catechin were 4.5~7.5 mL/g in ratio of ethanol to sample and -8~8℃ in extraction temperature. The actual values of yield, EGC, EC, EGCG, ECG, caffeine and total catechin, respectively, at the optimized conditions were 35.02%, 13.31%, 3.978%, 19.11%, 4.29%, 5.30% and 40.68% Key words：green tea, Camella sinensis L., optimization, response surface methodology, catechin 서 론 1) 녹차는 차나무(Camella sinensis L.)에서 어린잎을 채취하 여 가공한 것으로 전 세계적으로 많이 음용되고 있는 기호 식품중의 하나로 다양한 생리활성 효과도 있는 것으로 알려 져 있다(1). 녹차의 성분은 채엽 시기(2), 품종(3), 재배환경 (4) 등에 따라 차이가 난다고 알려져 있으며 특히 녹차에 함유되어있는 카테킨 화합물의 양이나 질은 pH, 온도, 효소 처리 등의 추출조건이나 방법에 따라서 크게 좌우된다고 보고되고 있다(5). 차는 당, 유기산, 질소화합물, polyphenol,