Microencapsulation of green coffee oil by complex coacervation of soy protein isolate, sodium casinate and polysaccharides: Physicochemical properties, structural characterisation, and oxidation stability

This study developed a combination method between protein-polysaccharide complex coacervation and freezing drying for the preparation of green coffee oil (GCO) encapsulated powders. Different combinations of soy protein isolate, sodium caseinate, sodium carboxymethylcellulose, and sodium alginate were utilised as wall materials. The occurrence of complexation between the biopolymers were compared to the final emulsion of the individual protein and confirmed by fourier transform infrared spectrometry and X-ray diffraction. The mean diameter and estimated PDI of GCO microcapsules were 72.57-295.00 mu m and 1.47-2.02, respectively. Furthermore, the encapsulation efficiency of GCO microcapsules was between 61.47 and 90.01 %. Finally, oxidation kinetics models of GCO and its microcapsules demonstrated that the zero-order model of GCO microcapsules was found to have a higher fit, which could better reflect the quality changes of GCO microcapsules during storage. Different combinations of proteins and polysaccharides exhibited effective oxidative stability against single proteins because of polysaccharide addition. This research revealed that soy protein isolate, sodium caseinate combined with polysaccharides can be used as a promising microencapsulating agent for microencapsulation of GCO, especially with sodium carboxymethylcellulose and sodium alginate, and provided useful information for the potential use of GCO in the development of powder food.