Feng Jin, Cai He, Wang Hua, Li Chunyang, Liu Songbai
Department of Food Science and Nutrition, Fuli Institute of Food Science, Zhejiang Key Laboratory for Agro-Food Processing, Zhejiang R & D Center for Food Technology and Equipment, Zhejiang University, 866 Yuhangtang Road, Hangzhou 310058, China; Department of Functional Food and Bio-active compounds, Institute of Agro-food Processing, Jiangsu Academy of Agricultural Sciences, Nanjing 210014, Jiangsu, China.
Department of Food Science and Nutrition, Fuli Institute of Food Science, Zhejiang Key Laboratory for Agro-Food Processing, Zhejiang R & D Center for Food Technology and Equipment, Zhejiang University, 866 Yuhangtang Road, Hangzhou 310058, China.
Food Chem. 2018 Feb 15;241:60-69. doi: 10.1016/j.foodchem.2017.08.055. Epub 2017 Aug 18.
Conjugates of ovalbumin (OVA) with (+)-catechin (C), (-)-epigallocatechin (EGC) or (-)-epigallocatechin gallate (EGCG) were synthesized through a free-radical grafting approach. The covalent binding between OVA and catechins was confirmed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS). OVA-catechin conjugates were further characterized by a combination of steady-state fluorescence spectroscopy, differential scanning calorimetry (DSC), Fourier transform infrared (FTIR) spectroscopy and circular dichroism (CD) analyses. Results suggested that the conjugates contained less α-helix but more β-sheet secondary structure than OVA. The catechin-grafting reaction led to improved surface hydrophobicity and decreased tertiary conformation stability of OVA. Compared with that emulsified by OVA, fish oil emulsion coated by conjugates demonstrated smaller droplet size, better storage stability and less viscosity. Besides, conjugates inhibited the lipid oxidation in fish oil emulsion more effectively than OVA because of their higher antioxidant activity and interfacial accumulation.
通过自由基接枝法合成了卵清蛋白（OVA）与（+）-儿茶素（C）、（-）-表没食子儿茶素（EGC）或（-）-表没食子儿茶素没食子酸酯（EGCG）的共轭物。通过十二烷基硫酸钠-聚丙烯酰胺凝胶电泳（SDS-PAGE）和基质辅助激光解吸/电离飞行时间质谱（MALDI-TOF-MS）证实了OVA与儿茶素之间的共价结合。通过稳态荧光光谱、差示扫描量热法（DSC）、傅里叶变换红外（FTIR）光谱和圆二色性（CD）分析相结合的方法对OVA-儿茶素共轭物进行了进一步表征。结果表明，与OVA相比，共轭物含有较少的α-螺旋但较多的β-折叠二级结构。儿茶素接枝反应导致OVA的表面疏水性提高，三级构象稳定性降低。与由OVA乳化的鱼油乳液相比，由共轭物包被的鱼油乳液液滴尺寸更小、储存稳定性更好且粘度更低。此外，由于共轭物具有更高的抗氧化活性和界面积累，它们比OVA更有效地抑制了鱼油乳液中的脂质氧化。
