Can natural pigments in different emulgel phases stabilize each other against UV radiation? Anthocyanin and β-carotene co-loaded in an emulgel based on soy protein isolate-gellan gum conjugates

Despite poor stability of natural pigments against degradation, using these colorants have attracted great interest due to their various beneficial effect on human health. Accordingly, in the present study, an emulgel based on soy protein isolate-gellan gum conjugate was fabricated via Millard reaction. Then, the effectiveness of emulgel on improving the stability of anthocyanin (ACN) and β-carotene (BC) with different loading concentration (5, 10, and 15 mg/mL) against UV-C irradiation was investigated. Degradation kinetic results exhibited the higher stability of ACN upon co-loading with BC, as the half-life of ACN in free aqueous solution, loaded and co-loaded in emulgel was found to be 0.698, 2.648 and 3.164 days, respectively. The emulgel effectively improved the stability of BC, as well, and no degradation was observed during storage time. The release studies of the pigments showed Fickian diffusion mechanism. Furthermore, their release patterns were found to be independent and differences among the release from individual or simultaneous loaded system were rather small. Overall, our findings elucidated the promising potential of co-loading within emulgel as a safe delivery system in stability enhancement of natural pigments.