A novel controlled-release Zn2+ supplementation based on egg yolk phosvitin: Structural, physicochemical and release characteristics

Zinc supplements are a common remedy for zinc dysregulation, and the controllable-release characteristic is important for preventing gastric mucosal damage and improving zinc bioavailability. In this work, egg-derived phosvitin, the most highly phosphorylated protein in nature, was used to prepare a Zn-chelating system to control Zn²⁺ release process in gastrointestinal tract. The results showed that the PSV-Zn chelates were successfully prepared, with the maximum chelation rate of 66%. The UV spectrum, fluorescence spectroscopy, and infrared spectroscopy results suggested that Zn²⁺ mainly binds to phosphate groups and aromatic amino acids of PSV. The chelation reaction altered the original structure of PSV, leading to the aggregation of molecules and the changes in elemental composition in particle surface of PSV-Zn complex. The chelates exhibited synergistic antioxidant activities. Interestingly, the in vitro simulations showed that PSV-Zn chelates exhibited a low Zn²⁺ release rate in stomach and a good Zn²⁺ release property in small intestine. This meant that the PSV-Zn complex has good release controllability, and thus possesses a potential to protect gastric mucosa and improve zinc bioavailability in small intestine. Therefore, this work provides a theoretical reference for preparing novel controlled-release Zn²⁺ supplements based on functional proteins.