Mechanism for improved protection of whey protein isolate against the photodecomposition of folic acid

Proteins have been widely used to prepare effective carriers for the protection of bioactive components. There were rare studies on proteins' change during protection and its impact on the protection, albeit they are important for the choosing of suitable proteins used as carrier materials. Folic acid is a synthetic form of folate but decomposes under ultraviolet irradiation. In this study, improved protection of whey protein isolate (WPI) against the photodecomposition of folic acid was investigated by using fluorescence and HPLC. During the vitamin decomposition, WPI's change was characterized in term of composition, structure, interaction with the vitamin or its decomposition products. Folic acid decomposition photosensitized indirect oxidation of WPI, leading to unfolding, degradation in concurrence with oligomerization . The increase in the absorbance and antioxidant activity contributed to the protein improved protection for folic acid. WPI could thus be a good carrier material for the encapsulation and protection of folic acid.