Self-assembly of soy proteins into nanofibrils is gradually considered as an effective method to improve their technical and functional properties. Ultrasound is a non-thermal, non-toxic and environmentally friendly technology that can modulate the formation of protein nanofibrils through controlled structural modification. In this research, the effect of ultrasound pretreatment on soy protein isolate nanofibrils (SPIN) was evaluated by fibrillation kinetics, physicochemical properties and structure characteristics. The results showed that the optimum ultrasound condition (20% amplitude, 15 min, 5 s on-time and 5 s off-time) could increase the formation rate of SPIN by 38.66%. Ultrasound reduced the average particle size of SPIN from 191.90 ± 5.40 nm to 151.83 ± 3.27 nm. Ultrasound could increase the surface hydrophobicity to 1547.67 in the initial stage of nanofibrils formation, and extend the duration of surface hydrophobicity increased, indicating ultrasound could expose more binding sites, creating more beneficial conditions for nanofibrils formation. Ultrasound could change the secondary and tertiary structure of SPIN. The reduction of α-helix content of ultrasound-pretreated soy protein isolate nanofibrils (USPIN) was 12.1% (versus 5.3% for SPIN) and the increase of β-sheet content was 5.9% (versus 3.5% for SPIN) during fibrillation. Ultrasound could accelerate the formation of SPIN by promoting the unfolding of SPI, exposure of hydrophobic groups and formation of β-sheets. Microscopic images revealed that USPIN generated a curlier and looser shape. And ultrasound reduced the zeta potential, free sulfhydryl groups content and viscosity of SPIN. SDS-PAGE results showed that ultrasound could promote the conversion of SPI into low molecular weight peptides, providing building blocks for the nanofibrils formation. The results indicated that ultrasound pretreatment could be a promising technology to accelerate SPIN formation and promote its application in food industry, but further research is needed for the improvement of the functional properties of SPIN.

将大豆蛋白自组装成纳米原纤维逐渐被认为是提高其技术和功能特性的有效方法。超声波是一种非热、无毒且环保的技术，可以通过受控的结构修饰来调节蛋白质纳米原纤维的形成。在本研究中，通过原纤化动力学、理化性质和结构特征评估了超声波预处理对大豆分离蛋白纳米原纤维（SPIN）的影响。结果表明，最佳超声条件（20%振幅、15 min、开启时间5 s、关闭时间5 s）可使SPIN的形成率提高38.66%。超声波将 SPIN 的平均粒径从 191.90 ± 5.40 nm 减小到 151.83 ± 3.27 nm。超声可以在纳米纤丝形成初期将表面疏水性提高至1547.67，并延长表面疏水性增加的持续时间，表明超声可以暴露更多的结合位点，为纳米纤丝的形成创造更有利的条件。超声波可以改变SPIN的二级和三级结构。在原纤维化过程中，超声预处理的大豆分离蛋白纳米原纤维 (USPIN) 的 α 螺旋含量减少了 12.1%（SPIN 为 5.3%），β 片层含量增加了 5.9%（SPIN 为 3.5%）。超声可以通过促进SPI的展开、疏水基团的暴露和β-折叠的形成来加速SPIN的形成。显微图像显示，USPIN 生成了更卷曲且更宽松的形状。超声降低了SPIN的zeta电位、游离巯基含量和粘度。 SDS-PAGE结果表明，超声波可以促进SPI转化为低分子量肽，为纳米原纤维的形成提供基础材料。结果表明，超声预处理可能是加速SPIN形成并促进其在食品工业中应用的一项有前途的技术，但需要进一步研究以改善SPIN的功能特性。