Effects of brewing time period on Physical and Chemical Quality, Antioxidant activity and Sensory quality of Gynostemma pentaphyllum Tea

Abstract

            The purpose of this research was to determine the physical qualities, chemical qualities, antioxidant activity, and sensory quality of the Gynostemma pentaphyllum tea different brewing time 5, 7, and 9 minutes at 90 °C. The results showed that the lightness (L*), the green color (a*), the yellow color (b*), total soluble solid (TSS), pH, total phenolic content, and total chlorophyll were increased over the brewing time.  The concentrations of citric acid, malic acid, and tartaric acid were constant throughout the 9-minute brewing. Antioxidant activity (IC₅₀) of tea brewing at 9 minutes was 3.01 ppm. The sensory evaluation scores (Hedonic scale 1-5) on color, taste, aroma, and overall acceptance of tea brewing at 9 minutes were 4.00, 2.18, 4.00, and 4.18, respectively.