Zhao Hui-Shuang, Ma Zhen, Jing Pu
Shanghai Food Safety and Engineering Technology Research Center, Bor S. Luh Food Safety Research Center, Key Lab of Urban Agriculture (South), School of Agriculture & Biology, Shanghai Jiao Tong University, Shanghai 200240, China.
Shanghai Food Safety and Engineering Technology Research Center, Bor S. Luh Food Safety Research Center, Key Lab of Urban Agriculture (South), School of Agriculture & Biology, Shanghai Jiao Tong University, Shanghai 200240, China.
Food Res Int. 2020 Sep;135:109289. doi: 10.1016/j.foodres.2020.109289. Epub 2020 May 5.
Betalain has been reported as water-soluble, nitrogenous pigments with biological activities. However, their sensitivity to thermal degradation limits their application during food processing. In this report, the interaction of betalain and soy protein isolate fibrils (SPI-F) was investigated through multiple microscopic and spectroscopic techniques and the thermal stability of betalain was assessed after heating treatment. AFM and TEM images showed that the complex of betalain and SPI-F was small, amorphous aggregate. Fluorescence spectroscopy revealed that SPI-F bound with betalain via hydrophobic interactions. Circular dichroism results showed the secondary structures of SPI-F was changed by betalain binding, with a decrease in α-helix (7.5-6.9%), β-turn (13.1-12.9%) and random coil (41.1-40.7%) and an increase in β-Sheet (38.3-39.5%). The addition of SPI-F decreased color loss and increased the thermal retention of betalain from 55.3% to 75.9%. These findings suggest that SPI-F has a protective effect on the thermal stability of betalain and facilitate the widespread application of betalain as natural colorants.
甜菜红素被报道为具有生物活性的水溶性含氮色素。然而，它们对热降解的敏感性限制了其在食品加工过程中的应用。在本报告中，通过多种显微镜和光谱技术研究了甜菜红素与大豆分离蛋白纤维（SPI-F）的相互作用，并在加热处理后评估了甜菜红素的热稳定性。原子力显微镜（AFM）和透射电子显微镜（TEM）图像显示，甜菜红素与SPI-F的复合物是小的无定形聚集体。荧光光谱表明，SPI-F通过疏水相互作用与甜菜红素结合。圆二色性结果表明，甜菜红素的结合改变了SPI-F的二级结构，α-螺旋减少（7.5-6.9%），β-转角减少（13.1-12.9%），无规卷曲减少（41.1-40.7%），β-折叠增加（38.3-39.5%）。SPI-F的添加减少了颜色损失，并将甜菜红素的热保留率从55.3%提高到75.9%。这些发现表明，SPI-F对甜菜红素的热稳定性具有保护作用，并有助于甜菜红素作为天然色素的广泛应用。
