Development of ovalbumin-pectin nanocomplexes for vitamin D3 encapsulation: Enhanced storage stability and sustained release in simulated gastrointestinal digestion

Vitamin D3 (VD3) is a fat-soluble vitamin and easily degraded under acidic conditions, which will greatly reduce its bioavailability. The use of complexes formed by protein-polysaccharide to control release and protect active compounds has become a feasible way in the food field. In this work, ovalbumin (OVA) and high methoxyl pectin (PEC) were applied to fabricate OVA-PEC nanocomplexes to encapsulate and protect VD3. The encapsulation efficiency of VD3 by OVA-PEC complexes could reach to 96.37%, and the storage stability of VD3 was obviously improved after encapsulation. The in vitro simulated gastrointestinal experiments combined with SEM and SDS-PAGE were employed to observe the digestive behavior of OVA-PEC-VD3 nanocomplexes. A small amount of VD3 is released from OVA-PEC-VD3 nanocomplexes in simulated gastric fluid, while a large amount of VD3 is released in simulated intestinal fluid. The sustained release kinetic of VD3 from OVA-PEC-VD3 nanocomplexes was consistent with the law of Higuchi model. The preliminary molecular mechanism for VD3 encapsulation by OVA-PEC complexes was also investigated, and the formation of OVA-PEC-VD3 nanocomplexes is ascribed to the electrostatic interactions, hydrogen bonding and hydrophobic interactions among OVA, PEC and VD3. The results demonstrated that protein-polysaccharide complexes can effectively encapsulate VD3 and achieve the goal of sustained release in the simulated gastrointestinal tract, which have potential applications in food and medicine.