Establishment of oyster protein hydrolysate-chitosan oligosaccharide-zinc delivery system and its characterization, digestion & absorption in-vitro and in-vivo

Zinc deficiency highly influences human health while the effects of some zinc supplements (peptide-zinc complex) would be negatively attenuated by human gastrointestinal environments. Therefore, it is necessary to develop the embedding methods to improve the stability and absorption effects of zinc supplements. In this study, the chitosan oligosaccharide (COS) was used to react with oyster protein hydrolysates (OPH) for the formation of new zinc carrier. The selected conditions for preparing the OPH-COS-Zn complex were 4 mg/mL, 30°C and 80 min by testing the zinc-chelating capacity. The main binding sites of OPH-COS complex with zinc were presumed to be involved in amino, carboxyl and carbonyl groups. The OPH-COS-Zn delivery system showed high zinc ion release rate (57.04%) by offering high soluble zinc amounts (61.07%) and remained stable in gastrin phase but partially degraded in intestinal phase in gastrointestinal digestion in-vitro. Furthermore, the delivery system was successfully absorbed and carried zinc ions to the serosal side (0.3027 mg/L) in everted rat gut sacs model. The OPH-COS-Zn delivery system showed better in-vivo temporary dynamic absorption of zinc (7.63 μmol/dL) than OPH-Zn (7.07 μmol/dL) and ZnSO4 (6.09 μmol/dL), showing slow-release effects of zinc ions. This experiment provided the theoretical foundation for further study of embedding effects of peptide-based zinc supplements.