Optimisation of wall material composition of freeze–dried pumpkin seed oil microcapsules: Interaction effects of whey protein, maltodextrin, and gum Arabic by D–optimal mixture design approach

D–optimal mixture design approach was used for optimisation of wall material composition including whey protein concentrate (WPC), maltodextrin, and gum arabic to effectively encapsulate cold–pressed pumpkin seed oil (CPPSO) by freeze–drying. Interaction and/or synergistic effects of these wall materials on the rheological and physical properties of oil–in–water emulsions and some physicochemical characteristics of microcapsules were examined. Rather than individual effects of each wall material component, effects of their interactions were dominant on the quality attributes of emulsions and microcapsules. Microencapsulation by freeze–drying decreased α–, γ– and total tocopherols and total phenolic contents (TPC) of CPPSO. Two wall material compositions (12.28% WPC + 5% maltodextrin +2.70% gum arabic or 10% WPC + 5% maltodextrin +5% gum arabic) with increased emulsion stability, encapsulation efficiency, solubility, total polyunsaturated fatty acids (PUFA) content and decreased wettability time and total saturated fatty acids (SFA) content were predicted by optimisation tool.