大豆蛋白及其水解物的界面流变学行为和搅打性质
Interfacial Rheological Behavior and Whipping Properties of Soy Protein and Its Hydrolysates
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摘要: 为研究不同结构大豆蛋白在空气-水界面处的吸附行为,探究其与搅打起泡性质的关系,本文对大豆分离蛋白(SPI)、β-伴大豆球蛋白(7S)、大豆蛋白选择性水解产物(SPSH)和大豆蛋白限制性水解产物(SPLH)进行了聚丙烯酰胺凝胶电泳(SDS-PAGE)、界面剪切流变学和搅打起泡性的测定。SDS-PAGE表明SPI由7S和11S组成,SPSH选择性水解后11S亚基带消失,仅保留了7S亚基,SPLH水解度1%,仅留下分子量约10 kDa的多肽链。界面剪切流变学行为表明SPI和7S的吸附速度较慢,SPLH可快速吸附至界面上。SPSH同时存在7S和多肽,既可快速吸附至界面,又能形成粘弹性强的界面膜。搅打实验表明SPSH和SPLH的泡沫膨胀率明显增加,分别从450%增至680%和700%。水解可以降低大豆蛋白的分子量,加快蛋白质吸附至界面的速度,从而增加泡沫膨胀率。本研究为大豆蛋白在充气食品的应用提供实际意义。Abstract: This article investigated soy protein isolate (SPI),β-conglycinin (7S),soy protein selective hydrolysate (SPSH) and soy protein limited hydrolysate (SPLH) by polyacrylamide gel electrophoresis (SDS-PAGE),interfacial shear rheology and whipping experiment to measure the adsorption behavior of different structural soy proteins at the air-water interface and to explore their relationships with whipping properties. SDS-PAGE indicated that SPI was consisting of 7S and 11S. After the selective hydrolysis,the 11S subunit band of SPSH disappeared and the 7S subunit of SPSH remained. The hydrolysis degree of SPLH was 1% with the molecular weight was about 10 kDa. The interfacial shear rheological behavior showed that the adsorption speed of SPI and 7S were slow and SPLH could be adsorbed quickly to the interface. 7S and peptides existed in SPSH,which made SPSH not only could be adsorbed to the interface quickly but also could form a viscoelastic interfacial film simultaneously. The whipping experiment results showed that the foam expansion of SPSH and SPLH increased significantly from 450% to 680% and to 700%,respectively. Hydrolysis could reduce the molecular weight of soy protein and accelerate the adsorption of protein at the interface,which resulted in the increase of foam expansion. This research provides practical significance for the application of soy protein in aerated foods.