Simultaneous extraction and decaffeination process optimization of green tea-based beverage using Box Behnken design-response surface methodology

Green tea is a popular beverage consumed worldwide after water, but some people cannot consume it due to its high caffeine concentration. One of the easiest methods to reduce caffeine and retain the bioactive compounds in green tea is through the simultaneous extraction and decaffeination process using hot water. Thus, this work aimed to achieve high flavonoid and low caffeine with antioxidant activity (IC₅₀) in green tea powder-based beverages through simultaneous extraction and decaffeination processes by the Box Behnken design-response surface methodology. Three independent factors were studied, namely extraction time (10 to 30 mins), decaffeination time (1 to 5 hrs), and decaffeination temperature (50 to 100°C), with three observed responses (total flavonoid, IC_50, and caffeine content). Process parameters were analyzed and optimized using the Design Expert program. The analysis of variance (ANOVA) was used to detect significant independent factors in each response. The results demonstrated that the extraction and decaffeination parameters influenced the total flavonoid, IC_50, and caffeine content of green tea powder-based beverages. The extraction time of 29.17 mins, decaffeination time of 5 hrs, and decaffeination temperature of 50°C was predicted to produce the green tea powder-based beverages with the lowest caffeine and IC_50, and high total flavonoid, with total flavonoid of 100.18 mg QE/g, IC₅₀ of 32.64 ppm and the caffeine content of 1.54 mg/ g, respectively. Based on paired t-tests, the verification revealed no significant difference with model predictions with a confidence interval of 5%. In conclusion, the optimized simultaneous extraction and decaffeination process utilizing the Box Behnken design-response surface methodology successfully produced green tea powder-based beverages with reduced caffeine content, enhanced flavonoid levels, and potent antioxidant activity, offering a promising solution for individuals seeking a healthier alternative to traditional green tea consumption.