Encapsulation of Olive Leaf Extract by Double Emulsion Method for Enriched Bakery Products: Enhancing Stability and Functionality

Abstract

Encapsulation of bioactive compounds is promising for enhancing their stability and functionality in food products. This study investigates the encapsulation of olive leaf extract using double emulsions, with a focus on their integration into cake formulations. Pea flour at varying concentrations (15%, 20%, 25%) was used as an emulsifier at the outer phase, aiming to optimize the encapsulation process for enhancing the stability and functionality of the core material. Characterization of double emulsions was done through analysis of droplet size and rheology of the emulsions as well as their influence on storage stability. Morphology of the double emulsions was investigated through optical microscopy and encapsulation efficiency was determined. Results revealed that a 25% pea flour concentration provided the lowest droplet size with a mean diameter of 6.16 ± 0.586 μm and a span value of 8.18 ± 0.438. Rheological analysis demonstrated non-Newtonian, shear-thinning behavior, with the highest apparent viscosity observed at 25% flour concentration, indicating a strong and stable emulsion matrix. The higher viscosity and smaller droplet size of the emulsions prepared using higher pea flour concentrations contributed to the stability of the emulsions. Subsequently, the incorporation of these double emulsions into cake formulations was investigated. Evaluation of cake properties, including color attributes, in vitro digestion kinetics, and baking stability, demonstrated the potential improvements in retention of the encapsulated extract with only minor changes in the product quality. Overall, this study highlights the use of double emulsions for encapsulating olive leaf extract and its applicability in enhancing the nutritional and functional properties of bakery products.