基于红外光谱分析热处理对牛乳蛋白质二级结构的影响  

Effect of Heat Treatments on the Secondary Structure of Milk Proteins Analyzed by Fourier Transform Infrared Spectroscopy

作　　者：孙佳悦 钱方[1] 姜淑娟[1] 妥彦峰[1] 牟光庆[1,2] 

机构地区：[1]大连工业大学食品学院,辽宁大连116034 [2]东北农业大学食品安全与营养协同创新中心,黑龙江哈尔滨150030

出　　处：《食品科学》2017年第23期82-86,共5页Food Science

基　　金：辽宁省自然科学基金面上项目(201602053);"十二五"国家科技支撑计划项目(2013BAD18B04);国家自然科学基金青年科学基金项目(31501513);国家自然科学基金面上项目(31571813)

摘　　要：运用傅里叶变换红外光谱技术对乳蛋白及其酰胺Ⅰ带进行解析,进一步用红外解谱法对其二级结构进行表征。以原料乳为对照,研究65℃/30 min(低温长时巴氏杀菌)、80℃/15 s(高温短时巴氏杀菌)、95℃/5 min(酸乳热处理)、137℃/5 s(超高温灭菌)等不同热处理条件对乳中蛋白质二级结构的影响。结果表明,热处理会导致乳蛋白间发生相互作用,乳蛋白原空间结构受到破坏,导致分子内氢键被破坏。不同热处理程度的乳蛋白酰胺Ⅰ带均向低波数方向发生了不同程度的红移,表明乳蛋白变性过程中疏水氨基酸残基暴露形成分子间氢键。同时热处理后乳蛋白各二级结构比例发生明显改变。α-螺旋含量显著降低(P<0.05),无规卷曲含量显著升高(P<0.05),β-转角及β-折叠含量在加热过程均呈先增加后减少变化趋势,表明热处理程度增强导致部分有序结构向无规卷曲结构转化,蛋白质热变性后会发生热聚集现象,且β-折叠、β-转角结构在热聚集体的形成过程中具有重要作用。Fourier transform infrared spectroscopy was used to investigate protein conformation changes in pasteurized milk （65 ℃/30 min and 80 ℃/15 s）, yoghurt （95 ℃/5 min） and ultra-high temperature sterilized milk （137 ℃/5 s） in comparison with raw milk as a control. The aim was to examine the effect of heat treatments on the secondary structure of milk proteins. The results showed that heat treatments could cause interactions between milk proteins, resulting in damage to the spatial structure of milk proteins and intramolecular hydrogen bonds. Different heat treatment conditions could result in different degrees of red shift of milk protein amide Ⅰ bands to lower wavenumbers, suggesting that intermolecular hydrogen bonds were formed between hydrophobic amino acid residues exposed during denaturation. Meanwhile, the secondary structure composition of milk proteins changed significantly after heat treatments; α-helix content decreased significantly （P 〈 0.05）, random coil content increased significantly （P 〈 0.05）, and both β-sheet and β-turn content decreased after an initial increase, indicating that the ordered structure was partially transformed to random coil. Protein aggregation occurred after thermal denaturation, and β-sheet and β-turn played an important role in the formation of heat-induced protein aggregates.

关 键 词：傅里叶变换红外光谱 热处理 乳蛋白 热聚集 二级结构 

分 类 号：TS252.1[轻工技术与工程—农产品加工及贮藏工程]