以大豆分离蛋白为基础原料,运用多种蛋白分析检测手段,深入探讨70、80、85、90、100℃热处理条件对大豆分离蛋白体外模拟消化特性影响。从蛋白质水解度(thedegreeofhydrolysis,DH)曲线来看,随着热处理温度的升高,DH曲线呈现先上升后下降的变化趋势,而长时间也会使DH呈现下降的趋势。傅里叶转换红外光谱及拉曼光谱图分析显示,经不同温度热预处理样品的消化产物二级结构中α-螺旋结构含量较未经预处理样品的高,而β-折叠结构含量降低,β-转角与无规卷曲结构含量变化不明显;随着时间的延长,α-螺旋结构含量呈先升高后降低的变化趋势,而β-折叠结构含量先降低后升高。拉曼光谱中酪氨酸峰变化较小且不规律,热处理使色氨酸残基更趋近于“包埋态”。
The effect of thermal pretreatments at different temperatures (70, 80, 85, 90, and 100 ℃) on the in vitro digestibility of soy protein isolate (SPI) was investigated using various protein analytical techniques. The curves of degree of hydrolysis (DH) showed an upward and then downward trend with pretreatment temperature or time. FTIR and Raman spectral analysis showed that thermal pretreatments resulted in a higher α-helix content and a lower β-sheet content in digestion products of SPI compared with the un-pretreated sample, while no significant changes in β-turn or random coilwere observed. The α-helix content rose firstly and then fell, whereas the opposite trend was noted for β-sheet content. The Raman spectral peaks of tyrosine revealed small and irregular changes, leading to a conclusion that heat-treated tryptophan residues were more close to “embedding state”.