Improving the Extraction of Catechins of Green Tea (Camellia sinensis) by Subcritical Water Extraction (SWE) Combined with Pulsed Electric Field (PEF) or Intense Pulsed Light (IPL) Pretreatment

Abstract

The aim of this study was to find the optimum condition of pulsed electric field (PEF) and intense pulsed light (IPL) for the enhancement of subcritical water extraction (SWE), which is an eco-friendly extraction method, for extracting tea catechins from green tea leaves (Camellia sinensis). The leaves were treated with PEF under conditions of electric field strength (1, 2 and 3 kV/cm) during 60 s. Moreover, IPL was applied at various voltages (800, 1000, and 1200 V) for 60 s. The SWE was performed for 5 min at varying temperatures (110, 130, 150, 170, and 190 °C). The maximum yield of total catechin was 44.35 ± 2.00 mg/g dry green tea leaves at PEF treatment conditions of 2 kV/cm during 60 s, as well as the SWE temperature of 130 °C. In the case of IPL treatment, the largest amount of total catechin was 48.06 ± 5.03 mg/g dry green tea leaves at 800 V during 60 s when the extraction temperature was 130 °C. The total catechin content was increased by 15.43% for PEF and 25.09% for IPL compared to the value of untreated leaves. This study verified that PEF and IPL had a positive effect on the enhancement of tea catechins extraction from green tea leaves using SWE.