Co-delivery of retinol and catechin encapsulated in O/W nanoemulsion and cycloamylose synergistically improved oxidative stability and bioavailability.

Abstract

Co-delivery of multiple bioactives with distinct physicochemical properties remains a critical challenge in food systems. A novel co-delivery system was developed to simultaneously encapsulate retinol and catechin (CT) by integrating an oil-in-water (O/W) nanoemulsion with cycloamylose (CA)-based inclusion complexes. Inclusion complexation with CA significantly enhanced the aqueous solubility and physicochemical stability of CT. Incorporation of the CA-CT complexes into the nanoemulsion simultaneously improved CT stability and retinol protection by suppressing lipid oxidation during storage while maintaining CT functionality. Among the formulations, EM/CA5-CT (containing 5% CA) exhibited the highest storage stability, extending the retinol half-life by 3.43-fold compared with the control emulsion. After in vitro digestion, EM/CA5-CT showed the highest retinol bioaccessibility, resulting in 2.59- and 2.38-fold increases in cellular uptake and antioxidant activity, respectively. This study presents an effective and mechanistically supported strategy for the co-delivery of multiple bioactives for functional food and nutraceutical formulations.