Study On Properties Of Self-emulsified Fish Oil Microcapsules

The self-emulsified fish oil microcapsules were produced by spray drying technique using low viscosity octenylsuccinate starch and maltodextrin as wall materials.On account of making fish oil into powder,it not only can inhibit the oxidation of fish oil,extend shelf life,and easy to use,transportation,storage of fish oil,but also to ensure that the fish oil health function is not lost.It is beneficial for the development of new products.In our previous study,the optimal wall material formula and spray drying process parameters of fish oil microcapsules were achieved by wall material screening,single factor and orthogonal experiments.In this paper,the fish oil microcapsules were prepared under the optimum conditions.And the physicochemical properties and stability of the fish oil microcapsules were investigated.Subsequently,the properties of microcapsules in vitro digestion were analyzed.The effects of storage temperature and p H on stability of microcapsules were studied by the traditional oxidation index and the multiple light scattering techniques.The main conclusions were as follows:(1)Sensory performances and basic physicochemical properties of the self-emulsified fish oil microcapsules were analysed.The fish oil microcapsules were the creamy white powder.They were uniform and delicate,had slight fish smell.The moisture content was 2.95%,bulk density 0.34 g/cm~3and angle of repose 32.8°.The microcapsules also exhibited excellent fluidity.After one year of storage at room temperature,the microcapsules still had good dispersion and solubility.The surface oil was 3.00%,the contents of EPA and DHA were 15.62 g/100 g and 17.75 g/100 g.The embedding efficiency reached 94.91%.And the peroxide value and acid value were 2.00 mmol/kg and 0.92 mg KOH/g,respectively.Except for surface oil content,other indexes met fish oil microcapsules standard stipulated by the Chinese aquatic industry.(2)The basic physicochemical properties of fish oil microcapsules were characterized by modern analytical techniques.The microcapsules were spherical as observed by optical microscopy and scanning electron microscopy.The structures of particles were compact and crack-free.The surface was partially wrinkled.Laser confocal microscopy showed that the holes in the wall materials were droplets of fish oil,and the fish oil microcapsules were typical multinucleated microcapsules.The particle size distribution was uniform(0.2-0.9μm).There was no significant change in average particle size after room-temperature storage for one month.The infrared spectra showed that there was no chemical reaction between the wall materials and the fish oil.The glass transition temperature of microcapsules was about 20.8℃,which indicated that the actual storage temperature should be lower than 20.8℃.Reconstituted emulsions of microcapsule exhibited shear-thinning behavior at low shear rate,and the behavior is conducive to the processing of emulsion,transport and storage.The results showed that the contents of EPA and DHA in fish oil were lower than those before microencapsulation,and the fish oil microcapsules were easily decomposed in the simulated gastric juice,which was beneficial for the digestion and absorption in the intestinal tract.(3)The effects of storage temperature and p H on the stability of fish oil microcapsules were investigated.The oxidation rate of fish oil microcapsules was the highest at 60℃and the lowest at 4℃.The oxidation value of the microcapsules at p H 6 and 7 was relatively lower than that atthe other p H.Before 18 h,the fish oil microcapsules exhibited higher stability at 25℃than 60℃.However,after 18 h,TSI was no longer suitable as an evaluation index for stability.There were no significant differences in the stability between the samples before 16 h.After 16 h,the stability of the sample decreased with decreasing p H.In summary,low temperature and neutral p H are more suitable for storage.