Study on extraction and purification of Polyphenols from dried green tea (Camellia sinensis) with microwave treatment

Abstract

The study on extraction and purification of polyphenol from dried green tea (Camellia sinensis) were investigated. The raw materials (dried green tea) were tested to determine the moisture, ash and fiber content with the results 3.06%, 5.72%, 2.03%, respectively. These samples were ground and sieved into discrete range of particle sizes and the range of 0.5-1mm was used in all experiments in report. Three parameters (type of solvent system, duration of microwave treatment and extraction temperature) were studied to find out the best conditions for polyphenol extraction from dried green tea. The best condition in each experiment was determined based on total polyphenol content (TPC) and extraction yield. TPC was quantified by a Spectrophotometric method. The results showed that extraction yield, TPC varied significantly, depending on the extraction solvent system, extraction temperature and microwave treatment duration. Highest TPC was obtained by using the methanol-in-water system (50%v/v) at 60oC with microwave treatment for 40 seconds (5.30gGAE/100gDW). Another important point of this study was that using chloroform and ethyl acetate to remove caffeine and un-wanted components and purify crude polyphenol of the extracts. The results showed that 92.5% of caffeine was removed and 98.3% polyphenol was retained in the final product.

Key words: Green tea Microwave treatment Total polyphenol content Caffeine content Decaffeination