부산대학교 도서관

Wheatgrass, the mature sprout of wheat seeds, is rich in nutrient components and antioxidant activity. Meanwhile, fermentation of the sugared black tea decoction with a symbiotic culture of yeast and acetic acid bacteria has also been proved to improve its nutrition and the in vivo antioxidant activity. In this study, a sugared black tea decoction supplemented with wheatgrass juice was used as a fermentation substrate. A starter comprising of yeast (Dekkera bruxellensis) and acetic acid bacteria (Gluconacetobacter rhaeticus and Gluconobacter roseus) was inoculated at 20% (v/v), and fermented statically at 29 ± 1oC for 12 days. Effects of ratios of wheatgrass juice to black tea on viable cell counts, pH, contents of organic acids, and water soluble vitamins during fermentation were investigated. The results showed that the pH values decreased gradually from 4.0 to 2.9 with time. Viable counts of yeast and acetic acid bacteria reached their maximum values 7.2 log cfu/mL at Day 6, and 5.1 log cfu/mL at Day 3, respectively. All fermented products were characterized as having increased amounts of organic acids (acetic acid, gluconic acid, and tartaric acid) and water-soluble vitamins (B1, B2, and pantothenic acid), but decrease in sugar contents after 12 days of fermentation. Contents of vitamins B1, B2, and pantothenic acid are 31.15-76.45 mg/100mL, 44.71-76.10 mg/100mL, and 5.97-15.88 mg/100mL, respectively. Consequently, fermentation of a wheatgrass juice supplemented black tea at ratio of 1 : 1 (v/v) (contains ca. 4% sucrose, w/v) for 6 days not only resulted in significant increase of organic acids and water soluble vitamins, but also had mild taste and better palatability. Our results suggest that intake of fermented black tea enhanced with wheatgrass juice is advantageous over unfermented one in terms of its nutritive values.