Co-encapsulation of vitamin D3 and curcumin in plant protein-based nanoemulsions: formulation optimization, characterization, and in vitro digestion

Abstract

This study aimed to develop plant-based nanoemulsions (NE) for co-encapsulation of vitamin D₃ and curcumin, comparing the emulsifying properties of pea and potato proteins. Different oil and protein concentrations were tested, and formulations with the smallest particle size were characterized and submitted to harmonized static in vitro digestion. Formulations prepared with the highest protein concentration (10%) and lowest oil concentration (1%) led to NE with smallest particle size and lowest polydispersity index (PDI). Curcumin and vitamin D₃ were successfully co-encapsulated in both protein NE. During digestion, NE showed instability, particularly in the gastric phase, in which an increase in particle size was observed. Pea protein NE exhibited higher curcumin bioaccessibility (76.06 ± 12.05%) than potato protein NE (42.88 ± 3.58%), while the bioaccessibility of vitamin D₃ did not show significant differences. Curcumin stability was also higher in pea protein NE (21.44 ± 1.97%) compared to potato protein NE (12.38 ± 1.97%). These results showed that pea protein is more suitable for produced plant-based NE for co-encapsulation of these bioactive compounds. This work contributes to the development of plant-based NE as promising carriers for the co-encapsulation of bioactive compounds, envisaging the fortification of food products, especially plant-based foods, in response to the growing demand for sustainable alternatives.