Co-encapsulation of vitamin D3 and <i>Cordia myxa</i> fruit peel extract in nanoemulsions

Purpose This study investigated the production of free and encapsulated nanoemulsions using Cordia myxa fruit peel (CMFP) extract and vitamin D3. Design/methodology/approach The CMFP extract was obtained using an ultrasonic technique, and its characteristics such as total phenolic content (TPC), antioxidant activity, cytotoxicity and gas chromatography-mass spectrometry (GC/MS) analysis were assessed. CMFP was encapsulated in vitamin D3 oil droplets of nanoemulsion prepared by ultra-homogenization using calcium alginate polymer. The nanoemulsions were evaluated for 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging activity, antimicrobial activity, morphology, Fourier transform infrared (FTIR) analysis and release rate in a simulated gastrointestinal model. Findings The GC/MS results revealed that pyrocatechol, cholestanoids and propionaldehyde were the predominant compounds in the extract. The highest cytotoxicity effect of CMFP was observed at concentrations of 6.25 and 12.5 ppm of the extract. Encapsulated nanoemulsions exhibited the highest antimicrobial activity against Escherichia coli (ATCC 35218). The antioxidant activity of the free and encapsulated nanoemulsions ranged from 25.81 to 36.08 mg/100g and 49.25–55.7 mg/100g, respectively. Free nanoemulsions showed a higher release rate in the simulated gastric model compared to encapsulated ones. The FTIR spectrum allowed for the identification of functional groups responsible for antioxidant and antibacterial properties, indicating that these properties of the nanoemulsions were maintained. Originality/value This study demonstrates the successful co-encapsulation of CMFP extract and vitamin D3 in nanoemulsions, which significantly enhanced the stability, bioavailability and functional properties of both compounds. Encapsulated nanoemulsions exhibited higher antioxidant and antimicrobial activities compared to their free counterparts, with controlled release in simulated gastrointestinal conditions. These findings confirm that nanoemulsion-based encapsulation is an effective strategy to protect and enhance the bioactivity of plant extracts and vitamins, supporting their potential use in functional food products and therapeutic application.