Effects of Nanoemulsions’ Droplet Size and Natural Antioxidants’ Hydrophilicity on Oxidative Stability and Mechanical Properties of Alginate Beads Filled with Linseed Oil Nanoemulsion

This study focused on fabricating linseed oil-in-water nanoemulsions (LON) at different pressures of 50 and 150 bar (named as LON50 and LON150, respectively) using a high-pressure homogenizer. Subsequently, these nanoemulsions were encapsulated in alginate hydrogel beads. It was observed that higher homogenizing pressure led to smaller droplet size (108.57 nm), harder beads (222.54 N), less LON release from the beads, and higher oxidation rate, as well as more reduction in α-linolenic acid content during the storage time. To increase the oxidative stability of LON150, natural antioxidants including clove essential oil (CEO), rosemary extract (RE), and a mixture of both (CEO+RE) were separately incorporated into the oil phase of LON (LON150-CEO), alginate aqueous dispersion (LON150-RE), and both lipid and aqueous phases (named as LON150-CEO+RE), respectively. It was shown that LON150-CEO+RE had weaker mechanical properties than LON150-RE and LON150-CEO. In addition, this sample (LON150-CEO+RE) showed the lowest oxidation rate and the minimum α-linolenic acid loss (9.82%) during storage. The highest LON release rate from the beads was related to LON150-RE. The results of this study might help in designing bioactive lipids-filled hydrogel beads with appropriate chemical stability and mechanical properties.