Optimization of spray-drying process to manufacture green tea powder and its characters

Tea leaves (Camellia sinensis) have many health benefits due to their abundance of polyphenols with antioxidant activity, most notably epigallocatechin-3-gallate (EGCG). To protect those bioactive compounds, the spray-drying technique of green tea-extracted solution is conducted because of encapsulating. This study aimed to optimize the spray-drying condition using the response surface methodology (RSM) with respect to the maximal polyphenol content of the product. Furthermore, the characterizations of resulting powder were determined. The results showed that optimal spray-drying temperature, input flow rate, and whey protein isolate (WPI) content were evaluated at 136℃, 6.8 rpm, and 10.3% of dry basis, respectively. The obtained green tea powder products, which got from optimal spray-drying process, achieved total polyphenol content (TPC), EGCG, and caffeine content of 322.06 mg GAE/g, 11.4%, and 2.8% of dry basis, respectively. This result revealed the feasibility of green tea leaves to produce tea powder rich in EGCG and polyphenols by spray-drying technique, potentially contributing to the diversification of tea products.