超声处理对大豆亲脂蛋白结构及溶解性的影响

Effect of Ultrasonic Treatment on Structure and Solubility of Soybean Lipophilic Protein

为探明超声处理对大豆亲脂蛋白(Lipophilic protein,LP)结构及溶解性的影响,将分离提取的LP在不同条件下进行超声处理,采用十二烷基硫酸钠-聚丙烯酰胺凝胶电泳(SDS-PAGE)、傅里叶变换红外光谱(FITR)、内源和外源荧光强度、差示扫描量热法(DSC)分析超声处理对LP结构及溶解性的影响。结果表明:SDS-PAGE显示,超声处理并不能改变LP的分子量分布,但能改变亚基的含量;红外光谱及内源、外源荧光光谱显示,不同的超声处理条件对LP的二、三级结构均会产生不同程度的影响,随着超声强度的增加,α-螺旋先减少、后增加,β-折叠先增加、后减少,在360 W超声功率下处理10 min时内源、外源荧光强度最强;在360 W超声功率下处理10 min和240 W超声功率下处理20 min时对LP的热稳定性、溶解性的改善效果最佳,变性温度提高6~7℃,溶解度提高约20个百分点,而超声功率过大时则会对LP的功能性质产生负面影响。通过试验得出最佳超声条件为:在360 W超声功率下处理10 min,LP理化性质最适合应用于食品工业。

Aiming to investigate the effects of ultrasonic treatment on the structure and solubility of soybean lipophilic protein(LP).The extracted LP was ultrasonically separated under different conditions,and the effect of ultrasonic treatment on the structure and solubility of LP was analyzed by using sodium dodecyl sulfate-polyacrylamide gel electrophoresis(SDS-PAGE),Fourier transform infrared spectroscopy(FITR),endogenous,exogenous fluorescence intensity and differential scanning calorimetry(DSC).The results showed that SDS-PAGE showed that the ultrasonic treatment could not change the molecular weight distribution of LP,but could change the content of subunits,infrared spectrum and endogenous and exogenous fluorescence spectra.It was showed that different ultrasonic treatment conditions had different effects on the second and third structures of LP.With the increase of ultrasonic intensity,α-helix was firstly decreased and then increased,β-fold was increased first and then decreased.The endogenous and exogenous fluorescence intensity was the strongest when treated at 360 W ultrasonic power for 10 min,and the thermal stability and solubility of LP were improved after treatment with 360 W ultrasonic power for 10 min and 240 W ultrasonic power for 20 min.The denaturation temperature was increased by 6~7℃,the solubility was increased by 20 percentage points,and it would have a negative impact on the functional properties of LP when the ultrasonic power was too large.Combined with the test results,it was concluded that the physicochemical properties of LP were most suitable for food applications after treatment at 360 W ultrasonic power for 10 min.