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Separation of epigallocatechin-3-gallate from crude tea polyphenols by using Cellulose diacetate graft

Hong ZHU, Peiyong QIN

《化学科学与工程前沿（英文）》 2011年第5卷第3期页码 330-338 doi: 10.1007/s11705-010-1104-6

摘要： This study demonstrates a new Cellulose diacetate graft -cyclodextrin (CDA- -CD) copolymer asymmetric membrane prepared by a phase inversion technique for the separation of (-)-epigallocatechin-3-gallate (EGCG) from other polyphenols in crude tea. The graft copolymer, CDA- -CD, was synthesized by prepolymerization of cellulose diacetate (CDA) and 1,6-hexamethylene-diisocyanate (HDI), which was then grafted with -cyclodextrin ( -CD). Surface and cross-section morphologies of the CDA- -CD membranes were analyzed by using scanning electron microscopy (SEM). Fourier transform infrared spectroscopy (FT-IR) indicated that the -CD was grafted onto the CDA by chemical bonding. The influences of the HDI/CDA mass ratio and the catalyst mass fraction on the -CD graft yield were investigated. The optimum conditions of a HDI/CDA mass ratio of 0.35 g·g and a catalyst mass fraction of 0.18 wt-% produced a -CD graft yield of 26.51 wt-%. The effects of the -CD graft yield and the concentration of the polymer cast solution on the separation of EGCG were also investigated. Under optimum conditions of a -CD graft yield of 24.21 wt-% and a polymer concentration of 13 wt-%, the purity of EGCG increased from 26.51 to 86.91 wt-%.

关键词： (-)-epigallocatechin-3-gallate (EGCG) tea polyphenols CDA-β-CD

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Study on the microwave-assisted extraction of polyphenols from tea

Liyun WANG, Peiyong QIN, Yan HU,

《化学科学与工程前沿（英文）》 2010年第4卷第3期页码 307-313 doi: 10.1007/s11705-009-0282-6

摘要： This study demonstrated a promising method for quickly extracting tea polyphenol (TP) by microwave-assisted extraction (MAE) technology. Some influential parameters, including MAE temperature, microwave power, concentration of extraction solvent, MAE time and the solid/liquid ratio, were investigated. The optimum condition of MAE was obtained by dual extraction with 60% ethanol (v/v) and the solid/liquid ratio 1:12 g/mL at 80°C for 10 minutes under the microwave power 600 W. The yield of TP was 96.5% under the described condition. Compared with traditional methods, including hot reflux extraction (HRE), ultrasound-assisted extraction (UAE) and supercritical fluid extraction (SFE), the extraction time was saved 8 times than that of HRE, and the yield was increased by 17.5%. The extraction time at comparable levels of production was saved 2 times, and the energy consumption was one fourth that of UAE. The extraction time was saved 5 times than that of SFE, and the yield of TP was increased by 40%. Moreover, compared with MAE of TP studied by others, it decreased the solid/liquid ratio from 1 ∶ 20 to 1 ∶ 12 g/mL without 90-min pre-leaching time, and the yield of TP was increased by 6%–40%.

关键词： energy consumption microwave-assisted extraction optimum condition pre-leaching concentration

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Impact and inhibitory mechanism of phenolic compounds on the formation of toxic Maillard reaction products in food

Jing TENG, Xiaoqian HU, Ningping TAO, Mingfu WANG

《农业科学与工程前沿（英文）》 2018年第5卷第3期页码 321-329 doi: 10.15302/J-FASE-2017182

摘要：

As one of the dominant reactions occurring during thermal treatment of food, the Maillard reaction not only leads to the formation of aroma, browning color and taste compounds, but also contributes to the formation of some unpleasant toxic substances including acrylamide, heterocyclic amines and advanced glycation end products. Polyphenols, one of the most abundant antioxidants in the human diet, are contained in different kinds of foods. In this review, some recent studies on the impact of dietary polyphenols on the formation of acrylamide, heterocyclic amines and advanced glycation end products formed during the Maillard reaction are summarized, including the research work conducted with both chemical model systems and real food model systems; the possible inhibitory mechanisms of different polyphenols are also summarized and discussed in this review. Basically we found that some dietary polyphenols not only scavenge free radicals, but also react with reactive carbonyl species, thus lowering the formation of toxic Maillard reaction products. This review provides a useful theoretical foundation for the application of polyphenols in food safety, and suggests some directions for further study of natural products as inhibitors against the formation of toxic substances in thermally processed food.

关键词： advanced glycation end products acrylamide food safety heterocyclic amine Maillard reaction polyphenols