Optimizing the extraction parameters of epigallocatechin gallate using conventional hot water and ultrasound assisted methods from green tea

Abstract

Epigallocatechin gallate (EGCG) is the main polyphenol present in green tea and is also known to possess various beneficial health effects. Extractions of EGCG, epigallocatechin (EGC), epicatechin gallate (ECG), and epicatechin (EC) from green tea were investigated by both conventional hot water extraction and ultrasound assisted extraction (UAE) with water and ethanol. Response Surface Methodology was used in order to optimize the extraction conditions for obtaining maximum amount of EGCG in the extracts. Pilot scale conventional hot water extraction and UAE with water in continuous flow mode were also conducted for industrial use. UAE with ethanol was significantly (p <0.05) efficient to extract more EGCG, EGC, ECG, and EC than conventional hot water extraction and UAE with water. At optimum conditions, almost 100 and 50% more EGCG content was obtained in UAE with ethanol than conventional hot water extraction and UAE with water, respectively. The optimal conditions for UAE of EGCG with ethanol were 66.53 degrees C, 43.75 min and, 67.81% ethanol. Conventional hot water extraction can easily be scaled up to a pilot scale and can be used for green tea beverage production. UAE should also be scaled up to a pilot scale by an efficient design either using an ultrasound probe in a larger volume continuously or ultrasound probes on each side of the extractor tank with an agitation system. (C) 2018 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.