Plant and Animal Protein Mixed Systems As Wall Material for Microencapsulation of Mānuka Essential Oil: Characterization and in Vitro Release Kinetics

Combination of plant and animal protein diet is becoming a valuable source of nutrition in the modern diet due to the synergistic functional properties inherent in these protein complexes. Moreover, the synergy between animal and plant proteins can contribute to the high stability and improved solubility of the encapsulated bioactive ingredients (e.g., essential oils). Therefore, the study was designed to evaluate the plant (pea protein (PP) and lupine protein (LP)) and animal protein (whey protein, WP) mixed systems as a wall material for microencapsulation of mānuka essential oil, as an example of bioactive compound. Moreover, physicochemical properties and in vitro release profile of encapsulated mānuka essential oil were studied. Mānuka essential oil microcapsules exhibited low moisture content (5.3–7.1 %) and low water activity (0.33–0.37) with a solubility of 53.7–68.1 %. Change in wall material ratio significantly affected the color of microcapsules, while microcapsules prepared with 1:1 protein/oil ratio demonstrated a high encapsulation efficiency (90.4 % and 89.4 %) for protein mixed systems (PP + WP and LP + WP), respectively. Microcapsules further showed low values for lipid oxidation with a high oxidative stability and antioxidant activity (62.1–87.0 %). The zero order and Korsmeyer–Peppas models clearly explained the release mechanism of encapsulated oil, which was dependent on the type and concentration of the protein mixed used. The findings demonstrated that the protein mixed systems successfully encapsulated the mānuka essential oil with controlled release and high oxidative stability, indicating the suitability of the protein mixed systems as a carrier in encapsulation and application potential in development of encapsulated functional foods.