Enhancing the stability of protein-polysaccharides emulsions via Maillard reaction for better oil encapsulation in spray-dried powders by pH adjustment

Lipid oxidation remains a major problem faced by the dairy industry. The bio-active ingredient (oil/milkfat) can be shielded by encapsulation within a secondary material. Emulsion stability is one of the main requirements for the production of oil/fat microcapsules with low levels of free surface fat and better encapsulation efficiency. This study focused on the use of sodium caseinate (NaCas)-lactose complex; conjugated via the Maillard reaction, as encapsulating materials, and investigated the effect of pH on the stability of protein-polysaccharide oil-in-water (O/W) emulsions. Subsequently, the properties of spray dried oil microcapsules, including encapsulation efficiency, insolubility, wettability, and microstructure, were analysed. The results demonstrated that better NaCas-lactose interactions were achieved at pH 11, with enhanced adsorption of the conjugates at the oil droplet particles and subsequently better emulsifying properties and stability. Additionally, a better oil entrapment (95.2 ± 3.7%) by the cross-linked protein and lactose was achieved when the pH of NaCas-lactose mixture was adjusted to 11 as compared to a pH of 7.5 (73.1 ± 2%). The outcome showed that it was possible to achieve stable microcapsules with oil loading as high as 80%, and with similar functional properties as those with 40% oil loading.