Factorial design optimization of natural biopolymer-based emulsions for the co-encapsulation of vitamins A and E

The fortification of food products with lipophilic vitamins represents an effective strategy to address nutritional deficiencies. However, the susceptibility of vitamins A and E to degradation during processing and storage limits their direct incorporation into food matrices. Emulsion-based encapsulation systems have emerged as promising delivery vehicles to improve the stability of these bioactive compounds while maintaining their functionality.⁽¹⁾

This study aimed to optimize oil-in-water emulsions for the co-encapsulation of vitamins A (retinyl palmitate) and E (α-tocopheryl acetate). A factorial experimental design comprising twelve formulations was employed to evaluate the influence of three biopolymers (pea protein, gelatine and sodium alginate), two emulsifiers (Tween 80 and soy lecithin), and the presence or absence of calcium chloride as a crosslinking agent on the emulsion stability. All formulations contained sunflower oil as the lipid phase and were coated with a 0.2% chitosan solution to enhance protection against acidic conditions.⁽²⁾

The emulsions were characterized in terms of particle size, zeta potential and sedimentation index. In addition, physical stability was assessed through a qualitative visual scoring system developed for this study and by accelerated stability testing under alternating storage conditions (4^°C/40^°C) over seven days.⁽³⁾

The results demonstrated that formulation composition significantly affected microcapsules suspension stability. Among the evaluated systems, sodium alginate-based emulsions stabilized with soy lecithin and prepared without calcium chloride exhibited the highest physical stability, maintaining lower sedimentation, favourable colloidal properties and no significant phase separation throughout the study conditions. These findings suggest that the combination of sodium alginate and soy lecithin provides an effective stabilization mechanism without the need for ionic crosslinking. The optimized formulation represents a promising encapsulation system for the incorporation of vitamins A and E into fortified food products, contributing to the development of functional ingredients with improved physical stability and potential application in bakery products.

Acknowledgments: This work was financed by European Regional Development Fund through the Program CENTRO2030 of Portugal 2030, project CENTRO2030-FEDER-01197600| HAPPYBREAD. FCT is also acknowledged for the financial support through the Strategic Research Center Project UIDB/00102/2020 (DOI: doi.org/10.54499/UIDB/00102/2025 and DOI: doi.org/10.54499/UID/PRR/00102/2025).

Margarida Oliveira holds a Master’s degree in Chemical Engineering, specializing in Process, Environment and Energy, from the University of Coimbra. Her MSc dissertation focused on the valorization of lignin for the production of bio-based polymer composites, contributing to research on sustainable materials and circular economy strategies. She is currently a research fellow at the Department of Chemical Engineering of the University of Coimbra within the HAPPYBREAD project, where she develops innovative functional bread formulations using sustainable regional ingredients. Her research interests include sustainability, biomass valorization, and environmentally conscious technologies.