EXTRACTION PROFILE OF FLAVAN-3-OLS FROM INTACT GRAPE SEEDS WITH AQUEOUS ETHANOL AND COMPARISON OF GRAPE SEED EXTRACTS FROM INTACT AND PULVERIZED SEEDS

Effect of ethanol concentration, temperature and time course on the extraction of (+)-catechin, (-)-epicatechin, and polymeric proanthocyanidins (PAs) from intact grape seeds was investigated. The optimum ethanol concentration was 60 and 40% for fresh and dried grape seeds, respectively. The higher the temperature showed the higher extraction effectiveness. The extraction rate of flavan-3-ols with ethanol/water (60:40, v/v) at 60°C was high up to 6 hours, where the recovery reached 90%. After 6 hours the extraction rate became slow, and the recovery reached 95% after 24 hours. Flavan-3-ols content in three lots of seeds from the factory appeared to be lower than that in the seeds manually prepared in the laboratory. On the contrary, the ratios of polymers to monomers in the seeds from the factory were remarkably higher than those in the dried seeds prepared in the laboratory. The high value of the ratio suggests that monomers may elute more rapidly than polymers into the juice during grape juice production. The comparison between grape seed extracts from intact and pulverized seeds were investigated. Both recovery and content of PAs in the extracts from intact grape seeds were relatively higher than those from pulverized seeds at more than 90 and 80%, respectively. The content of PAs in the grape seed extract from intact grape seeds was 9-34% higher than that of pulverized seeds. These results suggested that intact grape seeds are superior to pulverized seeds in the production of grape seeds extract.