藜麦多肽与食品多酚复合物的制备、表征及功能性研究

Preparation,Characterization and Functional Study of Quinoa Polypeptide Complex with Food Polyphenols

研究常用食品多酚(茶多酚(TPs)、竹叶抗氧化物(AOB))对藜麦多肽(QPs)结构、抗氧化性和抑菌性的影响。采用荧光分光光度计、傅里叶红外光谱仪探究QPs和多酚复合过程的结构变化,运用ANS探针分析QPs表面疏水性,并通过粒径、电位等指标对复合胶粒进行表征。荧光光谱结果表明,QPs与多酚复合后,QPs的固有荧光发生猝灭,且随多酚添加量的增加而降低,固有荧光光谱的最大发射波长发生红移。QPs与TPs复合后,表面疏水性显著降低(P<0.05),QPs∶TPs添加比例为1∶2时,ANS荧光强度由(74.13±1.67)AU,降低至(62.14±1.36)AU;而QPs与AOB复合后,表面疏水性无显著变化(P>0.05)。二级结构分析表明,所有复合样品中QPs的β-折叠、α-螺旋、无规则卷曲的百分含量下降,β-转角的百分含量增加。QPs∶TPs为1∶2时,β-折叠、α-螺旋、无规则卷曲和β-转角的百分含量分别为43.58%,17.20%,12.92%和26.30%;QPs∶AOB为1∶2时,β-折叠、α-螺旋、无规则卷曲和β-转角的百分含量分别为49.60%,14.99%,9.79%和25.62%。此外,QPs与TPs、AOB复合后能够显著提高QPs的抗氧化活性和对大肠杆菌和金黄色葡萄球菌的抑制活性(P<0.05)。这些发现表明TPs和AOB在改善QPs功能特性方面可行,以及QPs-多酚复合物在食品配料及功能性食品体系中具有潜在用途。

The effects of tea polyphenols(TPs)and antioxidant of bamboo leaves(AOB)on quinoa polypeptides(QPs)properties were investigated.Polyphenols induced structural changes,affected antioxidant and antibacterial properties of the polypeptides.The structural changes of QPs with polyphenols in all the composite samples were studied by Fourier transform infrared and fluorescence spectroscopy.ANS probe was used to analyze the surface hydrophobicity of QPs,particle size and potential were used to characterize the QPs-polyphenol particles.The fluorescence results showed that the intrinsic fluorescence of QPs was quenched and decreased with the increase of the number of polyphenols added,and the maximum emission wavelength was red-shifted.Secondary structure analysis showed that the percentage of β-fold,α-helix and random coil of QPs decreased,while the percentage of β-turn increased in all composite samples.When the ratio of QPs to TPs was 1∶2,the percentages of β-fold,α-spiral,random crimp andβ-corner were 43.58%,17.20%,12.92%and 26.30%,respectively.When the ratio of QPs to AOB was 1∶2,the percentages of β-folding,α-helix,random curling andβ-corner were 49.60%,14.99%,9.79% and 25.62%,respectively.TPs significantly reduced the surface hydrophobicity of QPs(P<0.05),When the ratio of QPs∶TPs was 1∶2,the fluorescence intensity of ANS decreased from 74.131.67AU to 62.141.36AU;but AOB had no significant effect on the surface hydrophobicity of QPs(P>0.05).In addition,the combination of QPs with TPs or AOB significantly improve the antioxidant activity and inhibitory activity of QPs against Escherichia coli and Staphylococcus aureus(P<0.05).These findings demonstrate the feasible application of TPs and AOB to improve the functional properties of QPs and the potential use of QPs-polyphenol composites in food ingredients and functional food systems.