ENHANCEMENT OF THE FUNCTIONAL PROPERTIES OF COFFEE THROUGH FERMENTATION BY TEA FUNGUS (KOMBUCHA)

The antioxidant and starch hydrolase inhibitory activities and the polyphenol contents of three roasted coffee powders (fine-ground coffee - FGC, coarse-ground coffee - CGC and instant coffee - IC) were determined following fermentation by the Kombucha tea fungus for 7 days. A statistically significant decrease (P < 0.05) in the pH was observed in FGC from 5.0 to 4.1. The chlorogenic acid content statistically significantly increases (P < 0.05) in CGC and FGC with final values of 12.9 and 13.2 mg/L, respectively. The caffeic acid content showed statistically significant increases (P < 0.05) only in FGC with a final value of 28.4 mg/L. Statistically significant increases (P < 0.05) in both starch hydrolases were observed from day 5 onward in all three beverages. In conclusion, this study provided preliminary evidence on the enhancement of the antioxidant and starch hydrolase inhibitory potential of coffee beverages through fermentation with the tea fungus.