Encapsulation of echium oil by electrospraying and mono- or coaxial spray-drying using plant protein hydrolysates as emulsifiers

The development of echium oil-loaded nano-microcapsules by electrospraying, mono- and coaxial spray-drying was investigated. Brewers' spent grains (BT) or defatted grape seed flour (GT) hydrolysates were used as plant-based emulsifiers. The oxidative stability of the capsules was assessed by Electron Spin Resonance (ESR). Electrosprayed particles had narrow size distribution, mostly <1.5 μm, increased specific surface area and low encapsulation efficiency (EE =61%). On the contrary, capsules produced with mono- and coaxial spray-drying mostly ranged from 2 to 10 μm and had higher EE (>80%), showing higher oxidative stability. BT, exhibiting higher emulsifying capacity and leading to more viscoelastic interfacial films than GT, led to microcapsules with higher oxidative stability with no difference between mono- and coaxial processes. In contrast, coaxial spray-drying, resulting in capsules with core-shell structure, reduced oil leakage when using the less powerful emulsifier GT, enhancing oxidative stability when compared to the monoaxial process.