THE EFFECT OF HUMIDITY AND TEMPERATURE ON TOTAL POLYPHENOL CONTENT AND ANTIOXIDANT ACTIVITY OF BLACK GARLIC PRODUCED FROM PEELED CLOVES OF GARLICS

Abstract

Recently, using peeled cloves of garlics for produce black garlic has been investigated, but the effect of humidity and temperature on antioxidant activity and polyphenol content of black garlic produced from peeled cloves of garlic have not been studied yet. In this study, peeled cloves of garlics were fermented in a variety of temperatures (70oC, 75oC, 80oC, and 85oC), humidity (70%, 80%, and 90%), and aging time (6 days, 15 days, and 20 days), then total polyphenol contents and antioxidant activities of samples were analyzed. The data showed that humidity did not affect polyphenol contents and antioxidant capacities of final products but affected antioxidants formation rate instead. Furthermore, temperature has noticeable impact on polyphenol content and antioxidant capacity. At lower temperatures (70oC and 75oC), polyphenol contents and antioxidant activities were gradually increased during the fermentation. On the contrary, polyphenol contents and antioxidant activities of black garlics incubated at 80oC and 85oC rapidly increased at early stage, then they were stable or decrease during later stage. The optimal conditions (75oC, 90% relative humidity, and 15 days) to produce black garlic with high polyphenol concentration and antioxidant capacity is determined (8.07 ± 0.21 g GAE∙kg-1 DW and 82.21 ± 0.88%, respectively).