Flavour encapsulation in milk proteins – CMC coacervate-type complexes

Beta-pinene containing microcapsules were prepared by complex coacervation of milk proteins, i.e sodium caseinate (CN) and whey protein isolate (WPI), with carboxymethylcellulose (CMC). Milk proteins – CMC interactions were followed by ζ-potential measurements, while the initial emulsions were characterised for droplet size and biopolymer amount present at the oil/water interface. Response surface methodology was applied to investigate the effects of encapsulation processing variables, including protein/polysaccharide (pr/pl) ratio and volatile compoundʹs mass, on encapsulation yield, loading and efficiency as well as the morphological characteristics of the produced microcapsules. The obtained results revealed that it was possible to encapsulate β-pinene with milk proteins and CMC by complex coacervation, while most of the characteristics evaluated were affected by the process variables. Coacervates prepared at the highest pr/pl ratio of 6.99 and β-pinene mass (6.99 g) were the most effective in encapsulating the flavour compound, something that was more evident in the case of WPI–CMC mixture. Additionally, microcapsule structure, evaluated by Scanning Electron Microscopy analysis, was noticeably affected by the protein/polysaccharide ratio being compact when pr/pl was low and “spongy”-like when it was high.