Oxidative stability and physical properties of mayonnaise fortified with zein electrosprayed capsules loaded with fish oil

This study investigated the oxidative stability and physical properties of low-fat mayonnaise fortified with electrosprayed zein capsules loaded with fish oil. A high encapsulation efficiency (EE) (83 +/- 1%) was achieved in the encapsulates and semi-spherical capsules with rough surface and mean diameter of 2.4 +/- 0.7 mu m were obtained. The amount of primary oxidation products of the zein capsules did not increase over the storage, even though the initial content was higher compared to neat fish oil. Cryo-SEM images revealed that the capsules remained intact when they were incorporated into a water-based food matrix like mayonnaise. This explained the lower content of hydroperoxides at the end of the storage for the capsule-enriched mayonnaise (Mayo-C) when compared to mayonnaise enriched with neat fish oil (Mayo-F) (2 meq/kg oil vs. 6 meq/kg oil, respectively). Even though, volatile compounds from the secondary oxidation of omega-3, such as 2-ethylfuran and 1-penten-3-one were found in higher amounts in Mayo-F, a higher overall increase in all other secondary oxidation products was observed in Mayo-C. This increase was attributed to the formation of oxidation volatile compounds from the zein material, together with the oxidation of un-encapsulated fish oil droplets. Moreover, Mayo-C presented higher viscosity and droplet size than Mayo-F, which also increased during storage, although no further alterations of the emulsion like creaming were observed. Overall, these findings indicate the benefits of using zein as hydrophobic shell material for the development of omega-3 loaded-electrosprayed capsules intended to the enrichment of water-based food matrices when compared to the use of hydrophilic wall materials.