不同提取方法对葡萄渣凝缩类单宁化学组成的影响（英文）

Influence of different extraction methods on the chemical composition of grape pomace condensed tannins

分别采用酸沉淀法和冷冻干燥法从葡萄渣中提取凝缩类单宁,借助碳核磁共振波谱法(13C-NMR)和基质辅助激光解吸/电离飞行时间质谱法(MALDI-TOF),分析不同的提取方法对凝缩类单宁提取物化学结构和组成的影响。结果表明:这两种单宁提取物以原花青定类凝缩单宁为主,少量的原花青定上含有葡萄糖基取代基和没食子酸取代基,单宁单体间以C4-C8键连接;酸化凝缩类单宁分子聚合度高于冻干凝缩类单宁;同时,酸化凝缩类单宁的中碳水化合物含量低于冻干凝缩类单宁,但儿茶酸含量高于冻干凝缩类单宁。

Condensed tannins were extracted from grape pomace by acid precipitation and lyophilisation, respectively. Influence of the recovery methods on the chemical structure and composition of tannin extracts was investigated by using Carbon Nuclear Magnetic Resonance （ 13 C-NMR ） and MatrixAssisted Laser Desorption/Ionization Time of Flight （ MALDI-TOF） Mass Spectrometry. The results showed that the procyanidin units played a dominait role in two kinds of condensed tannin extracts, and small proportion glucose and gallic acid substitutions bonded in procyanidin units which was linked together by C4-C8 bond. The polymerization degree of acidified condensed tannins was higher than that of lyophilized condensed tannins. In addition, relatively low carbonhydrate and high catechinc acid content in acidified condensed tannins were observed compared with lyophilized condensed tannins. Different extraction methods had great influence on the chemical composition of grape pomace tannin extracts.