热诱导大豆分离蛋白聚集对谷氨酰胺转氨酶交联乳液凝胶性质的影响

Effect of heat-induced soybean protein isolate aggregation on the properties of transglutaminase crosslinked emulsion gel

大豆分离蛋白(soybean protein isolate,SPI)基乳液凝胶在食品工业中应用广泛。在商品化SPI生产过程中,不可避免会发生一定程度的热变性和聚集,对谷氨酰胺转氨酶(transglutaminase,TGase)交联蛋白产生影响。为探究不同热变性程度的SPI对TGase诱导SPI乳液凝胶的影响,制备了不同热处理温度的SPI,研究其乳化性、凝胶强度、持水/油性、凝胶形态,以及SPI浓度、油浓度对SPI乳液凝胶性质的影响。结果表明:随着热处理温度的增加,SPI稳定乳液的乳化活性和乳化稳定性呈显著增加趋势。95℃热处理显著增强了乳液凝胶的凝胶性能,其凝胶硬度是天然蛋白乳液凝胶的2.2倍。对于95℃热处理的SPI乳液凝胶,随着蛋白浓度或油浓度的增大,凝胶强度显著增加,气孔逐渐增大;所有样品均具有优异的持水性和持油性。SPI在经过热变性(95℃)处理后有利于经TGase诱导形成SPI乳液凝胶。

Soybean protein isolate(SPI)based emulsion gels are widely used in the food industry.In the production process of commercial SPI,a certain degree of thermal denaturation and aggregation inevitably occurs,and the aggregation state of soybean protein is an important factor affecting the performance of SPI-based emulsion systems and SPI-based emulsion gel systems.Therefore,for the actual processing,it is necessary to explore the influence of the degree of thermal aggregation of soybean protein on the gel properties of transglutaminase(TGase)cross-linked emulsion gels.To investigate the effect of SPI with different degrees of thermal denaturation on TGase induced SPI based emulsion gels,SPIs with different heat treatment temperatures were prepared,and the effects of thermal aggregation of SPI on emulsifying property,emulsion stability,gel strength,water/oil holding capacity,gel morphology and other properties were studied.In addition,SPI based emulsion gels with different protein concentrations(8%-12%)and different oil concentrations(5%-20%)were prepared to explore the effects of SPI and oil concentration on the properties of SPI based emulsion gels.The results showed that the emulsifying activity and emulsifying stability of SPI stabilized emulsions increased significantly with the increase of SPI heat treatment temperature.The clarification index of the SPI-stabilized emulsion also decreased significantly with increasing SPI heat treatment temperature.With the increase of SPI heat treatment temperature,the number of pores of the emulsion gel increased accordingly,and the size of pores also increased.The heat treatment of SPI at 95°C significantly enhanced the gel properties of the emulsion gel,and its gel hardness was 2.2 times that of the native SPI emulsion gel.For the SPI heat-treated at 95°C,as the protein concentration increased from 8%to 12%,the hardness of the SPI emulsion gels increased from 861.4 g to 2830.2 g correspondingly.The pore size showed a gradually increasing trend.For the emulsion gel of heat-treated SPI at 95°C,as the soybean oil concentration increased from 5%to 20%,the hardness of the SPI based emulsion gels increased correspondingly from 991.4 g to 2830.2 g.With the increase of oil concentration,the pore size of the SPI emulsion gel showed a gradually increasing trend.In addition,all samples have excellent water and oil holding capacity.The results have demonstrated that the thermal denaturation(95℃)of SPI is beneficial to the formation of SPI emulsion gel induced by TGase.