超声波处理对糯米粉中蛋白质特性的影响

Effect of ultrasonic treatment on protein properties in waxy rice flour

经超声波处理的糯米粉凝胶特性得到明显改善,研究其中淀粉的颗粒结构和特性未发现显著变化,提取经超声波处理的糯米粉中的蛋白质(protein extracted from ultrasound treated waxy rice flour,P-UT-WRF)与原糯米粉中的蛋白质(protein extracted from waxy rice flour,P-WRF),并进行对比,研究超声波功率、超声波时间和料液比对蛋白质的特性、结构和形貌的影响。结果表明:相比于P-WRF,当超声波功率为130 W、超声波时间为10 min、料液比为1∶2 g/mL时,P-UT-WRF特性变化最为显著,β-折叠和无规卷曲分别增加9.21%、39.60%,α-螺旋和β-转角含量分别降低29.16%、10.60%,变性温度(T d)和焓值(ΔH)分别降低10.74%、10.72%,溶解度和表面疏水性分别增加39.83%、16.16%,游离巯基含量增加38.84%,二硫键含量降低4.37%,355 nm处的荧光强度增加21.98%;P-UT-WRF的扫描电镜图显示其结构松散,孔洞密集。超声波处理破坏了糯米粉中蛋白质的形态结构和构象,使糯米粉的凝胶特性得到改善。

The gel properties of waxy rice flour treated by ultrasound were significantly improved,while there was no significant change for the starch.The protein extracted from ultrasound treated waxy rice flour(P-UT-WRF)was compared with the native protein extracted from the waxy rice flour(P-WRF),and the effects of different ultrasonic power,ultrasonic time and solid-liquid ratio on the morphology,structure and characteristics of protein were studied.Compared with P-WRF,the ultrasonic power was 130 W,ultrasonic time was 10 min,and the ratio of material to liquid was 1∶2 for P-UT-WRF,and the effect on the properties of the protein from waxy rice was the most significant.Compared with P-WRF,theβ-folding and random coil of P-UT-WRF increased by 9.21%and 39.60%,theα-helix andβ-angle content decreased by 29.16%and 10.60%,the denaturation temperature(T d)and enthalpy(ΔH)decreased by 10.74%and 10.72%,the solubility and surface hydrophobicity increased by 39.83%and 16.16%,the free sulfhydryl group increased by 38.84%,the disulfide bond decreased by 4.37%,and the fluorescence intensity at 355 nm increased by 21.98%,respectively.Scanning electron microscopy(SEM)showed that the morphology of P-UT-WRF had loose structures and dense holes.Therefore,the conformation change of proteins caused by ultrasonic treatment improved the gel properties of waxy rice flour.