Extraction of caffeine and catechins using microwave-assisted and ultrasonic extraction from green tea leaves: an optimization study by the IV-optimal design.

Abstract

In this research, optimal conditions for extraction of caffeine and polyphenols were established from Iranian green tea leaves. In the first step, caffeine was extracted with efficacy about 86% versed to 4.5% of EGC+EGCG. The EGCG+EGC was extracted from partially decaffeinated green tea leaves through microwave-assisted extraction (MAE) and ultrasound-assisted extraction (USE) with efficiency levels of 95 and 85%, respectively. The best results for the MAE process were obtained with 7.8min and three number of extraction cycles and for the USE process were as followed: time 57min, temperature 65°C, and the number of extraction cycles 3. The total phenol content values at the best conditions of MAE and the USE processes were 125±5 and 96±6mg gallic acid/g DW. The 50% inhibition (IC50) on 1,1-diphenyl-2-picrylhydrazyl (DPPH) were 56 and 66mg/g of phenol for the MAE and USE processes.