Extraction of Catechins from Green Tea Using Ultrasound

Abstract

Recently, hazardous properties of synthetic substances contained in foods and medicines have been observed. Therefore, the pharmacological actions of natural substances became the focus of attention. Catechins, which are polyphenols, are abundant in green tea. To extract green tea catechins, there are two types of method: extraction using hot water and organic solvents. In the extraction using hot water, green tea quality deteriorates and catechins are destroyed due to the heat applied. Accordingly, the extraction of catechins at low temperatures is appropriate, although the efficiency is low. Therefore, we attempted to increase the amount of catechins extracted with ultrasonic irradiation.

Optimization of ultrasound‐assisted water extraction conditions for the extraction of phenolic compounds from black mulberry leaves (Morus nigra L.)

“…For this purpose, extraction techniques have been researched and modified to obtain the catechins with minimum loss (Pasrija & Anandharamakrishnan, ; Vuong et al, ). Thermal degradation of polyphenols at high temperatures is one of the disadvantages of conventional solvent extraction method (Yue et al, ) High temperature may cause changes in quality and losses of catechins due to degradation and mainly to the epimerization of their structure (Chen et al, ; Koiwai & Masuzawa, ; Vuong et al, ). Koiwai and Masuzawa () showed that catechin extraction in green tea could be increased by ultrasonic irradiation at low temperature decreasing the risk of degradation of compounds compared with hot water extraction.…”

“…Thermal degradation of polyphenols at high temperatures is one of the disadvantages of conventional solvent extraction method (Yue et al, ) High temperature may cause changes in quality and losses of catechins due to degradation and mainly to the epimerization of their structure (Chen et al, ; Koiwai & Masuzawa, ; Vuong et al, ). Koiwai and Masuzawa () showed that catechin extraction in green tea could be increased by ultrasonic irradiation at low temperature decreasing the risk of degradation of compounds compared with hot water extraction. The results we obtained were similar to those of the other studies in which the amount of catechins in UAWE extracts was high when compared with CE extracts.…”

Antioxidant and Antimicrobial Activities of (‐)‐Epigallocatechin‐3‐gallate (EGCG) and its Potential to Preserve the Quality and Safety of Foods

“…Several methods have been evaluated for the extraction/isolation of EGCG or other tea polyphenols. The most widely used methods for the extraction have been water extractions (Demir, Serdar, & Sökmen, ; Kumar, Thakur, & De, ; Lee & Lee, ), solvent‐based extractions (Dong, Ye, Lu, Zheng, & Liang, ; Perva‐Uzunalić et al., ; Tay, Tan, Abas, Yim, & Ho, ; Ye, Li, Lu, Zheng, & Liang, ), microwave‐assisted extractions (Li & Jiang, ; Nkhili et al., ; Quan, Hang, Hai Ha, De, & Tuyen, ), and ultrasonic‐assisted extractions (Koiwai & Masuzawa, ; Lee et al., ; Sousa et al., ; Xia, Shi, & Wan, ). Polyphenols and especially EGCG are very susceptible to light, high extraction temperatures for prolonged periods of time, and alkaline conditions, causing their oxidation and degradation during extraction and food processing (Ananingsih, Sharma, & Zhou, ; Li, Taylor, Ferruzzi, & Mauer, ; Su, Leung, Huang, & Chen, ).…”

Processing Technologies for the Extraction of Value-Added Bioactive Compounds from Tea

“…UAE has been in use for a long time to extract bioactive compounds from various tea leaves, as referred to in Table 1. Most of the research work was on green tea leaves [121,[134][135][136][137][138][139][140][141][142][143] and Black tea [31, [136][137][138]143]. In addition, research has been carried out to extract bioactive from tea infusions [39], matte leaves [144,145], tea solids [146][147][148], tea seeds [131], yellow tea [122], white tea [136,137,149], and Oolong tea [136,137].…”