高强度超声处理对大豆7S和11S球蛋白结构和理化性质的影响

Effect of High Intensity Ultrasound on the Conformational and Physicochemical Properties of Soy 7S and 11S Globulin

以大豆7S和11S球蛋白为对象,研究了高强度超声处理(150、450、1350 W)在不同时间条件(15、30 min)下对7S和11S结构和理化性质的影响。结果表明:超声处理不改变7S和11S的一级结构,但能够使二级结构中各组分含量发生改变。同时,7S和11S的荧光强度在超声处理后降低,表面疏水性(H0)显著增加(P<0.05)。粒径分布测定显示7S和11S经超声处理后液滴粒径分布更加均匀,蛋白溶液的稳定性有所提升。DSC结果可以看出,超声后7S的焓值(ΔH)从1.22 J/g最多下降至0.17 J/g,11S从1.41 J/g最多下降至0.53 J/g,展开蛋白质结构所需的能量更少。在理化性质方面,超声处理后7S和11S的乳化活性和乳化稳定性显著增加(P<0.05),溶解度最多分别提高了12.85%和10.57%。此外,冷冻扫描电子显微镜(Cryo-SEM)观察微观结构显示,7S和11S超声后从较为有序的网状聚集状态转变为无序的状态。因此,采用高强度超声处理能够显著影响7S和11S的结构和理化性质。

The effects of high intensity ultrasound treatment(150,450,1350 W) on the conformational and physicochemical properties of soy 7 S and 11 S globulin for different durations(15,30 min) were investigated.The results showed that ultrasound treatment did not change the primary structures of 7 S and 11 S,but were able to change the content of the components in the secondary structure.Ultrasound treatment resulted varying degrees of reduction in fluorescence intensity and a significant increase(P<0.05) in surface hydrophobicity(H0) for 7 S and 11 S.Particle size distribution measurements showed that the droplets of 7 S and 11 S were more uniformly distributed after ultrasound treatment and that the stability of the protein solutions was improved.Differential scanning calorimetry(DSC) results showed that the enthalpy(ΔH) decreased from 1.22 J/g to 0.17 J/g for 7 S and from 1.41 J/g to 0.53 J/g for 11 S after sonication,requiring less energy to unfold the protein structure.In terms of physicochemical properties,the emulsification activity and emulsion stability of 7 S and 11 S increased significantly(P<0.05) after sonication,and the solubility increased by up to 12.85% and10.57%,respectively.In addition,cryo-scanning electron microscopy(Cryo-SEM) observations revealed that the microstructure of 7 S and 11 S changed after sonication from a more ordered reticular aggregated state to a disordered state.Thus,high intensity ultrasound treatment can obviously affect the structure and physicochemical properties of 7 S and 11 S.