热处理对高温煎煮和低温酶法提制绿茶多糖的影响

采用复合酶法提取和二乙基氨基乙基（DEAE）-纤维素52（DE-52）柱层析纯化制得茶多糖复合物TPC-1；采用煎煮提取、Sephadex G-200柱层析纯化获得茶多糖(TPC)复合物TPC-2。 高效液相凝胶渗透色谱 蒸发光散射检测表明，TPC-1和TPC-2经98 ℃水浴处理5 h后，TPC-1的主要均一性组分TPC-1a裂变为TPC-1a-1和TPC-1a-2 2个组分；圆二色（CD）谱显示TPC-1在194 nm呈现1个正Cotton效应峰，热处理后在216 nm处增加1个正Cotton效应峰；TPC-2经热处理后其中2种均一性组分TPC-2a和TPC-2b未变化，CD谱显示TPC-2在203、215和272 nm处均呈现显著的的正Cotton效应峰，经热处理后前2个峰消失。 98 ℃水浴热处理改变了低温复合酶法提制的茶多糖复合物TPC-1溶液构象和均一性组分的分布，未改变沸水煎煮提制的TPC-2的均一性组分的分布和凝胶色谱行为，但影响了其溶液构象。

Thermal Treatment on Tea Polysaccharide Conjugates Prepared from Green Tea by Extraction of Decoction and Complex Enzyme

Tea polysaccharide conjugates(TPC) named TPC-1 were prepared from low-grade green tea by extraction through complex enzymes method and purified by diethylaminoethyl(DEAE) cellulose(DE-52) column chromatography, while TPC-2 was prepared by extraction with boiling water and purified by Sephadex G-200 column chromatography. TPC-1 and TPC-2 were incubated respectively at 98 ℃ for 5.0 h. A single symmetrical peak corresponding to the main homogeneous component, TPC-1a in the chromatogram of high performance gel permeation chromatography(HPGPC) was split into two adjacent peaks representing two different components of TPC-1a-1 and TPC-1a-2. Circular dichroism(CD) spectra showed an additional positive Cotton effect for the peak at 216 nm along with the peak at 194 nm. HPGPC showed that incubation in water at 98 ℃ for 5.0 h has no effects on TPC-2 that contained two homogeneous components of TPC-2a and TPC-2b. The CD spectra of the treated sample revealed that the positive Cotton effects for peaks at 203 and 215 nm disappeared, while it retained for the one at 272 nm. The solution conformation and homogeneous component distribution of TPC-1 had been changed by heat treatment. But only solution conformation had been changed for TPC-2.