Study on the binding interaction and stability of whey protein concentrate-80 with folic acid

The aim of this study was to evaluate the effects of whey protein concentrate-80 (WPC80) and folic acid (FA) on protein structure, functional properties, and on the stability of FA through non-covalent interactions. The effect of FA on the structure of WPC80 was analyzed by intrinsic fluorescence spectroscopy, ultraviolet absorption spectroscopy, and circular dichroism. The results showed that FA induced changes in the local conformation and secondary structure content of WPC80. Moreover, the particle size distribution of the system showed a tendency to become smaller and the absolute value of the zeta potential increased; the surface hydrophobicity and free sulfhydryl content of WPC80 decreased with the increase of the FA concentration, and the foaming and emulsifying properties gradually improved with the increase of the FA concentration. This indicates that FA combined causes changes in the functional properties of WPC80. Meanwhile, the binding capacity of FA to WPC80 gradually increased with its concentration, and the combination enhanced the storage stability of FA under different temperatures, aerobic and ultraviolet irradiation. This study will provide a theoretical basis for the application of FA-fortified foods.