摘要
以接种外源优势菌黑曲霉发酵的云南普洱茶为原料,通过有机溶剂萃取得到茶褐素(TB),采用紫外(UV-vis)、红外光谱分析(IR)、凝胶色谱(GPC)等方法,对普洱茶发酵过程中茶褐素分子性质、光谱学性质的变化进行分析。结果表明:茶褐素分子结构组成中含有羧基和羟基,而且随发酵时间的延长,羧基含量增加,羟基含量减少,不同翻堆样茶褐素的化学结构有较大差异。各翻堆样茶褐素的重均分子量(Mw)均较大,而四翻样的数均分子量(Mn)最大,说明各翻堆样的茶褐素均为高分子聚合物,且四翻样中茶褐素高分子组分含量较多。一到四翻的茶褐素的紫外-可见光谱较为相似,在200、280、975nm附近有较强吸收峰,说明茶褐素组分中可能含有结合的蛋白质。不同翻堆样茶褐素红外光谱主要吸收峰大体上也是一致的,主要吸收为羟基信号,但仍可看出结合的蛋白质与多糖的信号。通过研究为普洱茶品质的形成与调控研究奠定了基础。
This research use the theabrownin,which extract from the Yunnan pu-erh tea ferment with foreign dominant bacteria Aspergillus niger,as research object,use ultraviolet spectrophotometry（UV）,infrared spectrophotometry（IR） and gel permeation chromatography（GPC） to analyze the changes of molecular and spectroscopy properties of theabrownin of pu-erh tea during the ferment.The results show that：the molecular structure of theabrownin contains carboxyl and hydroxyl,as the ferment time extend,content of carboxyl increase and content of hydroxyl decrease,the chemical structure of different pile-up all differ from each other.Weight-average molecular weight of different pile-up all large,the number-average molecular weight of four pile-up was the largest,these results show that the theabrownin of different pile-up were all high polymers,and the high polymers composition in four pile-up was higher than the others.The ultraviolet spectrophotometry of one to four pile-up were all similar,they all have strong absorption peak at 200 nm,280 nm and 975 nm,and indicate the composition of theabrownin may contain binding protein.The main absorption peak of infrared spectrophotometry of different pile-up theabrownin also similar to each other,the main absorption peak was hydroxyl signal,and there also have the signal of binding protein and polysaccharides.This research establishes the base on formation and control of the character of pu-erh tea.
出处
《食品科技》
CAS
北大核心
2013年第4期53-57,共5页
Food Science and Technology
基金
国家自然科学基金项目(30960241
30760152)
关键词
普洱茶
茶褐素
分子结构
光谱学性质
pu-erh tea
theabrownin
molecular structure
spectral properties
