Effect of Spray Drying Conditions on Physical and Chemical Properties of Dried Green Tea Extract (Camellia sinensis var. Oolong No 12).

Abstract

The effect of spray drying conditions on physical and chemical dried green tea (Camellia sinensis var. Oolong No 12) extract were observed. Tea extract was prepared from milled dried tea, dissolved in hot water at temperature 90°C and ratio of dried tea to water 1: 20 (w / v). The time of extraction used was 60 minutes, and pH value was 5.0. Then, tea extract was concentrated with ice maker machine until reached 3, 6 and 9% of total solid, and dried with spray drier with condition inlet air temperatures were 180, 200, 220°C, outlet air temperatures was controlled 75°C, blower speed was adjusted in 2500 rpm. The physical analysis, such as bulk density, color, solubility, hygroscopicity, and the chemical analysis, such as moisture content, total polyphenols content, antioxidant activity (DPPH assay), catechins, and caffeine content were determined. Results showed that different solid concentration of 3, 6, 9% in feed and inlet air temperatures of 180, 200, and 220˚C affected the variation of physical and chemical properties of green tea powder. An increase inlet air temperature, resulted in a significant decrease (p<0.05) in bulk density, hygroscopicity, total polyphenols and antioxidant activity. An increase of solid concentration in feed gave an increase in tea powder solubility, L, a, b value, and antioxidant activity. However, the total polyphenols contents were not affected by the increase. The condition of feed concentrated to 3% and inlet temperature at 220˚C was evaluated with the highest of physical, chemical results and the highest of kg water removal/hour by spray dryer.