Wang Yongchao, Sun Long, Peng Jianhong, Wang Zhengxuan, Zhao Tianrui, Cao Jianxin, Liu Yaping, Cheng Guiguang, Brennan Charles
Faculty of Food Science and Engineering, Kunming University of Science and Technology, Kunming, 650500, China; Yunnan International Joint Laboratory of Green Food Processing, Kunming 650500, China.
Faculty of Food Science and Engineering, Kunming University of Science and Technology, Kunming, 650500, China.
Food Chem. 2025 Oct 15;489:145010. doi: 10.1016/j.foodchem.2025.145010. Epub 2025 Jun 2.
Protein-polyphenol complexes have attracted increasing attention in the development of novel food ingredients owing to their potential health benefits. Purple rice (Oryza Sativa L.) is rich in proteins and polyphenols, particularly anthocyanins. This study investigated the effects of two extraction methods, alkaline extraction (0.2 % NaOH) and α-amylase degradation, on the structure, compositional components and physicochemical properties of purple rice proteins (PRP). Chemical analysis revealed that PRP extracted by alkaline solution (PRPA) and α-amylase degradation (PRPE) contained phenolic acids, flavonoids, hydrophobic amino acids, with cyanidin-3-O-glucoside identified as the predominant anthocyanin in these natural protein-polyphenol complexes. Notably, PRPA, characterized by its darker pigmentation, exhibited significantly higher total phenolic content (TPC) and total flavonoid content (TFC) compared to PRPE, indicating superior polyphenol retention in the protein-polyphenol complex. Furthermore, PRPA displayed higher protein content, enhanced thermal stability, and increased surface hydrophobicity, along with elevated levels of hydrophobic amino acids, total sulfhydryl groups, disulfide bonds, and ordered secondary structures (α-helix and β-sheet). In contrast, PRPE had superior solubility, higher β-turn content, and more exposed sulfhydryl groups. Scanning electron microscopy (SEM) revealed PRPA presented a compact, smooth surface, whereas PRPE exhibited a porous microstructure. Functionally, PRPE had enhanced water and oil absorption capabilities than PRPA. Although PRPA initially exhibited better foaming and emulsifying properties, PRPE displayed greater stability in these functionalities over time. Molecular docking studies further elucidated the mechanism of protein-polyphenol complex formation through hydrogen bonding, hydrophobic interactions, and π-π stacking between proteins and cyanidin-3-O-glucoside, with a binding energy of -8.1 kJ/mol, explaining the higher polyphenol retention in PRPA and its unique functional properties. These findings highlighted the potential of PRP as a natural protein-polyphenol complex for multifunctional ingredients in food applications.
由于其潜在的健康益处，蛋白质-多酚复合物在新型食品成分的开发中越来越受到关注。紫米（Oryza Sativa L.）富含蛋白质和多酚，尤其是花青素。本研究考察了两种提取方法，即碱性提取（0.2% NaOH）和α-淀粉酶降解，对紫米蛋白（PRP）结构、组成成分和理化性质的影响。化学分析表明，通过碱性溶液提取的PRP（PRPA）和通过α-淀粉酶降解提取的PRP（PRPE）含有酚酸、黄酮类化合物、疏水氨基酸，矢车菊素-3-O-葡萄糖苷被鉴定为这些天然蛋白质-多酚复合物中的主要花青素。值得注意的是，PRPA色素沉着较深，与PRPE相比，其总酚含量（TPC）和总黄酮含量（TFC）显著更高，表明蛋白质-多酚复合物中多酚保留能力更强。此外，PRPA蛋白质含量更高，热稳定性增强，表面疏水性增加，同时疏水氨基酸、总巯基、二硫键和有序二级结构（α-螺旋和β-折叠）水平升高。相比之下，PRPE具有更好的溶解性、更高的β-转角含量和更多暴露的巯基。扫描电子显微镜（SEM）显示PRPA呈现致密、光滑的表面，而PRPE呈现多孔微结构。在功能方面，PRPE的吸水和吸油能力比PRPA更强。虽然PRPA最初表现出更好的起泡和乳化性能，但随着时间的推移，PRPE在这些功能方面表现出更大的稳定性。分子对接研究进一步阐明了蛋白质与矢车菊素-3-O-葡萄糖苷之间通过氢键、疏水相互作用和π-π堆积形成蛋白质-多酚复合物的机制，结合能为-8.1 kJ/mol，解释了PRPA中更高的多酚保留率及其独特的功能特性。这些发现突出了PRP作为一种天然蛋白质-多酚复合物在食品应用中作为多功能成分的潜力。
