Targeted regulation of hygroscopicity of soybean antioxidant pentapeptide powder by zinc ions binding to the moisture absorption sites

- The soybean antioxidant peptide (SAP) could possess zinc-chelating activity.
- Zinc ions chelated with moisture absorption sites of SAP.
- Hygroscopicity of SAP and SAP-zinc complex powders was investigated by DVS and LF-NMR.
- At 93.4% RH, moisture sorption capacity of SAP decreased after zinc ion chelation.

In the present study, a targeted regulation of hygroscopicity of soybean antioxidant pentapeptide (SAP) powder was explored by zinc ions binding to its moisture absorption sites. Scanning electron microscopy, X-ray diffraction analysis, Fourier transform infrared spectroscopy and an energy-dispersive X-ray spectroscope were used to confirm the formation of the SAP-zinc complex. The results showed that morphology of SAP-zinc complex belonged to crystalline nanoparticles. The moisture sorption/desorption kinetics of the SAP-zinc complex changed compared to that of the SAP. In particular, the moisture sorption capacity of the SAP decreased and the distribution of adsorbed water changed after zinc chelation. Based on the binding of zinc ions to the moisture absorption sites, the hygroscopicity of SAP powder could be target regulated. Thus, this study could provide a new method to regulate the hygroscopicity of peptide powder.