Herein, 1 wt% quinoa protein isolate (QPI) was exposed to sonication using a 20 kHz ultrasonicator equipped with a 6 mm horn (14.4 W, 10 mL, up to 15 min) or high hydrostatic pressure (HHP, up to 600 MPa, 15 min) treatments at pH 5, pH 7, and pH 9. The changes to physicochemical properties were probed by SDS-PAGE, FTIR, free sulfhydryl group (SH), surface hydrophobicity (H0), particle size and solubility. As revealed by SDS-PAGE, substantial amounts of 11S globulin participated in the formations of aggregates via S-S bond under HHP, particularly at pH 7 and pH 9. However, protein profiles of QPI were not significantly affected by the sonication. Free SH groups and surface hydrophobicity were increased after the sonication treatment indicating protein unfolding and exposure of the embedded SH and/or hydrophobic groups. An opposite trend was observed in HHP treated samples, implying aggregation and reassociation of structures under HHP. HHP and sonication treatments induced a decrease in ordered secondary structures (random coil and β-turn) accompanied with an increase in disordered secondary structures (α-helix and β-sheet) as probed by FTIR. Finally, the sonication treatment induced a significant improvement in the solubility (up to ∼3 folds at pH 7 and ∼2.6 folds at pH 9) and a reduction in particle sizes (up to ∼3 folds at pH 7 and ∼4.4 folds at pH 9). However, HHP treatment (600 MPa) only slightly increased the solubility (∼1.6 folds at pH 7 and ∼1.2 folds at pH 9) and decreased the particle size (∼1.3 folds at pH 7 and ∼1.2 folds at pH 9). This study provides a direct comparison of the impacts of sonication and HHP treatment on QPI, which will enable to choose the appropriate processing methods to achieve tailored properties of QPI.

在此，使用配备 6 mm 喇叭（14.4 W，10 mL，长达 15 分钟）或高静水压（HHP，高达 600 MPa， 15 分钟）在 pH 5、pH 7 和 pH 9 下进行处理。通过 SDS-PAGE、FTIR、游离巯基 (SH)、表面疏水性 (H0)、粒径和溶解度来探测理化性质的变化。 SDS-PAGE 显示，大量 11S 球蛋白在 HHP 下通过 SS 键参与聚集体的形成，特别是在 pH 7 和 pH 9 下。然而，QPI 的蛋白质谱并未受到超声处理的显着影响。超声处理后游离的 SH 基团和表面疏水性增加，表明蛋白质解折叠和嵌入的 SH 和/或疏水基团的暴露。在 HHP 处理的样品中观察到相反的趋势，这意味着 HHP 下结构的聚集和重新结合。通过 FTIR 探测，HHP 和超声处理导致有序二级结构（无规线圈和 β 转角）减少，同时无序二级结构（α 螺旋和 β 折叠）增加。最后，超声处理导致溶解度显着提高（pH 7 时高达~3 倍，pH 9 时~2.6 倍），粒径减小（pH 7 时高达~3 倍，pH 9 时~4.4 倍）。 9).然而，HHP 处理 (600 MPa) 仅略微增加了溶解度（pH 7 时约 1.6 倍，pH 9 时约 1.2 倍）并减小了粒径（pH 7 时约 1.3 倍，pH 9 时约 1.2 倍）。本研究直接比较了超声处理和 HHP 处理对 QPI 的影响，这将使我们能够选择适当的处理方法来实现 QPI 的定制特性。