Microencapsulation of niger seed oil: Impact of protein types, maltodextrin ratios, and drying methods on stability and functional properties

In this study, the influence of protein isolate types (whey, soy, and pea protein isolates), protein-to-maltodextrin (MLD) ratios (1:1, 1:2, 1:3, and 1:4), and drying methods (freeze drying and spray drying) for enhancing stability and functional properties of microencapsulated niger seed oil (MNO) was investigated. The protein isolate type and MLD ratio significantly influence the physicochemical properties, encapsulation efficiency (EE), and oxidative stability of MNO. The whey protein isolate (WPI) exhibited superior solubility, emulsifying capacity, and rehydration properties than the soy and pea protein isolates. The MLD ratio impacted viscosity, bulk density, and oxidative stability, with the higher MLD ratios (1:4) resulted into lower viscosity and bulk density while higher flowability. The spray drying produced microcapsules with smaller particle sizes, higher EE, and enhanced oxidative stability while freeze drying resulted in more porous structures with lower EE. The encapsulation process significantly improved the oxidative stability of niger seed oil, with WPI-based microcapsules exhibiting the highest stability. The results suggest that the optimization of protein-to-MLD ratio and drying method are important in maximizing the EE, particle size, and stability of MNO powder.