Study On The Preparation Of Multilayer Emulsion And Microcapsule Of Linseed Oil

Linseed oil contains more than 50% α-linolenic acid, and it is an excellent source of α-linolenic acid for nutrition needs. However, linseed oil can be easily oxidized because of its high concentration of unsaturated acids, which can create harmful products and reduce the product shelf life. This study prepared multilayer emulsions by electrostatic layer-by-layer(Lb L) self-assembly, and spray-dried them with corn syrup solids to prepare microencapsulated linseed oil. Microencapsulation is an effective technology for inhibiting the oxidation of linseed oil during the processing, transportation and consumption.And microcapsule can control the releaserate of linseed oil in the body.This study investigated the preparation of multilayer emulsions by electrostatic layer-by- layer deposition. The final composition of the primary emulsion was 10.0% linseed oil and 0.9% WPC; secondary emulsion was 5.0% linseed oil, 0.45% WPC and 0.2% pectin; and the tertiary emulsion was: 2.5% linseed oil, 0.225% WPC, 0.1% pectin, and 0.2% chitosan.The stability of emulsions at different p H and salt concentrations were examined. Primary emulsion stabilized by WPC was highly unstable and would lead to droplet aggregation at p H 4 or p H 5. However, a secondary emulsion stabilized by WPC-pectin layer showed to be stable from p H 4 to 8. The tertiary emulsions was stable from p H 3 to 5, but became unstable at higher p H values.The strength of the electrostatic interaction and van der Waals will decrease in the presence of salt due to the reduction of the electrostatic screening effects and the Hamaker function, so the salt concentration in emulsions may affects the stability of the emulsions, showing as the decreasing of the ζ-potential value and the increasing of the mean particle size. It also showed that the outer layer plays a major role in determining particle charge and stability in the multilayer emulsions, emulsions with different layers had different stability at the same p H and salt concentration.The emulsions were spray dried with corn syrup to make microcapsules. The results of microcapsulation efficiency showed that powdered linseed oil produced by multilayer emulsions had high microencapsulation efficiency. The fatty acid composition would not change during the process.The samples were evaluated as to stability at 60 °C for 30 days compared to non encapsulated linseed oil. During the storage, surface oil content of the the microcapsule with three layers change slightly; and the acid value and peroxide value rose slightly, the oxidative stability decreased a little. It showed that the multilayer linseed oil microcapsule had excellent stability against oxidation as measured by storage study.The results of in vitro digestion model showed that the multilayer structure can retard lipid hydrolysis, which may be used for sustained release of the oil.