酶法改性对甘薯蛋白质结构及理化性质的影响

Effect of enzymatic modification on structure and physicochemical properties of sweet potato protein

为研究酶解处理后甘薯蛋白质(sweet potato protein,SPP)结构及理化性质的变化,选用5种蛋白酶(碱性蛋白酶、中性蛋白酶、木瓜蛋白酶、胰蛋白酶和胃蛋白酶)对SPP进行酶解处理,分析蛋白酶酶解产物结构变化,测定其水解度、溶解度、持水性、乳化性等理化指标。结果表明:木瓜蛋白酶和碱性蛋白酶处理后SPP水解度较其他3种蛋白酶处理后更高;SDS-PAGE凝胶电泳图谱显示,经酶解后SPP中处于高分子量的条带被降解为25 ku的低分子量条带;FTIR光谱分析表明,在5种蛋白酶酶解产物的二级结构中α-螺旋和β-转角是其主要结构;木瓜蛋白酶和胰蛋白酶处理后SPP溶解度较高;碱性蛋白酶、木瓜蛋白酶和中性蛋白酶酶解产物持油性、乳化性及起泡性优于其他蛋白酶酶解产物,而胰蛋白酶酶解产物持水性较佳。综上,这一研究可为SPP活性研究及新产品开发提供理论基础。

The physicochemical properties and structural changes of sweet potato protein(SPP)after enzymatic hydrolysis were studied.5 different proteases(alkaline protease hydrolysate,neutral protease hydrolysate,papain hydrolysate,trypsin hydrolysate and pepsin hydrolysate)were used to enzymatically hydrolyze sweet potato protein,further to analyze the structural changes of proteolysis products,and determine its hydrolysis,solubility,water retention,emulsification and other physical and chemical indicators.The results showed that the hydrolysis degree of SPP treated with papain and alkaline protease was higher than that treated with other three proteases.SDS-PAGE gel electrophoresis showed that the high molecular weight bands of sweet potato protein were degraded to 25 ku low molecular weight bands after enzymolysis.FTIR spectroscopic analysis showed thatα-folding andβ-turning were the main secondary structures of the hydrolyzed products of 5 proteases.The solubility of SPP was higher after papain and trypsin treatment.The hydrolytic products of alkaline protease,papain and neutral protease had better oil retention,emulsification and foaming properties than those of other proteases,while the hydrolysis products of trypsin had better water holding capacity.This study provides a theoretical basis for the discovery of sweet potato protein activity and the development of new products.