Department of Engineering, Aarhus University, Gustav Wieds vej 10, Aarhus 8000, Denmark; Department of Dairy Science, Faculty of Agriculture, Cairo University, Giza 12613, Egypt.
Department of Dairy Science, Faculty of Agriculture, Cairo University, Giza 12613, Egypt.
Food Chem. 2018 Feb 15;241:281-289. doi: 10.1016/j.foodchem.2017.08.101. Epub 2017 Sep 1.
Multi-functional phenolic emulsifiers were prepared by covalently coupling β-Lactoglobulin (βLg) to caffeic acid (CA) using crosslinker chemistry at different pH conditions (pH 2.5, 6.0, and 8.5). The resulting bioconjugates were characterized by MALDI-TOF MS, differential scanning calorimetry (DSC), fluorescence-quenching, infrared and circular dichroism spectroscopies. Furthermore, the emulsifying and antioxidant properties of βLg-CA conjugates were evaluated and compared to native β-Lactoglobulin and the non-covalent β-lactoglobulin/caffeic complex (βLg/CA). Results showed: 1) An optimal molar ratio (8:1) of caffeic acid to βLg was obtained at pH 6; 2) DPPH activity of βLg-CA increases as the number of CA units coupled increases; 3) βLg-CA conjugates displayed comparable or superior water solubility than native βLg and βLg/CA. Moreover, DSC results showed that coupling of CA with βLg significantly increased the thermal stability of βLg. In summary, βLg-CA conjugates can act as effective antioxidant emulsifiers and stabilizers and may find application in food and cosmetic industries.
多功能酚类乳化剂是通过在不同 pH 值条件（pH 2.5、6.0 和 8.5）下使用交联化学将β-乳球蛋白（βLg）共价偶联到咖啡酸（CA）上来制备的。所得的生物缀合物通过 MALDI-TOF MS、差示扫描量热法（DSC）、荧光猝灭、红外和圆二色性光谱进行表征。此外，还评估和比较了βLg-CA 缀合物的乳化和抗氧化性能，以及天然β-乳球蛋白和非共价β-乳球蛋白/咖啡酸复合物（βLg/CA）。结果表明：1）在 pH 6 时，CA 与βLg 的最佳摩尔比（8:1）；2）βLg-CA 的 DPPH 活性随着偶联的 CA 单位数量的增加而增加；3）βLg-CA 缀合物的水溶性与天然βLg 和βLg/CA 相当或更高。此外，DSC 结果表明，CA 与βLg 的偶联显著提高了βLg 的热稳定性。总之，βLg-CA 缀合物可以作为有效的抗氧化乳化剂和稳定剂，可能在食品和化妆品行业中得到应用。
