Impact of ultrasound‐assisted extraction of polyphenols and caffeine from green tea leaves using high‐performance thin‐layer chromatography

Abstract

AbstractTea is the most popular daily drink consumed globally, with a high concentration of caffeine and polyphenols. In this study, the effects of ultrasonic‐assisted extraction and quantification of caffeine and polyphenols from green tea were investigated and optimized using 23‐full factorial design and high‐performance thin‐layer chromatography. Three parameters were optimized to maximize the concentration of caffeine and polyphenols extracted using ultrasound: crude drug‐to‐solvent ratio (1:10–1:5), temperature (20–40°C), and ultrasonication time (10–30 min). The optimal conditions achieved from the model for tea extraction were as follows: crude drug‐to‐solvent ratio, 0.199 g/ml; temperature, 39.9°C; and time, 29.9 min; the extractive value was found to be 16.8%. Images from scanning electron microscopy showed that the matrix underwent a physical alteration and cell wall disintegration, which intensified and accelerated the extraction. This process might be simplified using sonication, which results in a higher extractive yield and a significant concentration of caffeine and polyphenols than the traditional approach, with a smaller quantity of solvent and faster analytical times. The result of high‐performance thin‐layer chromatography analysis proves a significant positive correlation between extractive value and caffeine and polyphenol concentrations.