Preparation And Characterization Of An Emulsion Based On Antarctic Krill Oil And The Properties Of Its Hydrogel System

Antarctic krill oil has high nutritional value,rich in n-3 polyunsaturated fatty acids,astaxanthin,vitamin A,vitamin E and other nutrients,and has higher bioavailability than fish oil.Antarctic krill oil has many biological activities,but has an unpleasant fishy smell,unsaturated fatty acids and other components of krill oil are easily oxidized and deteriorate.Meanwhile,krill oil has high viscosity and low water solubility,causing difficulties in processing.To solve this problem,the study used ultrasonic emulsification technology and selectd food-grade pea protein isolate as an emulsifier to prepare krill oil emulsion,which is different from conventional emulsions that rely on small molecule surfactants and can construct a safer and more stable emulsification system.Then,a hydrogel system embedded with PPI-krill oil emulsion was established to improve the stability of the product while realizing the slow release of biologically active components in the body.This paper screened the food-grade materials,emulsification methods and compound oil phase suitable for preparing krill oil emulsion,explored the effects of different process parameters on the properties of the emulsion and optimized them,and finally prepared emulsion-based hydrogel beads and studied stability and in vitro digestion characteristics of them.This study aims to provide scientific theoretical basis for improving the quality of krill oil products and broadening its application range.The main research contents and conclusions of this paper are as follows:1.Screened food-grade materials and emulsification methods for the preparation of Antarctic krill oil emulsion.Antarctic krill oil emulsions stabilized by 4 kinds of proteins and 2 kinds of polysaccharides were prepared separately.The particle size distribution,rheological properties,microstructure,X-ray diffraction,Fourier infrared scanning,thermodynamic behavior analysis and storage stability were used to select the most suitable food-grade material,pea protein isolate(PPI).The prepared emulsion had an average particle size of 6.29 nm and and remained stable without stratification after 21 days of storage.The PPI dispersion was emulsified using high-pressure microfluidization and ultrasound,respectively.Combined with atomic force microscopy,circular dichroism,and endogenous fluorescence spectroscopy,the effects of the two emulsification methods on the properties of the emulsion were compared.The results showed that the particle height and width obtained by ultrasound emulsification method were reduced to 1.2-6.2 nm and 7-20 nm,respectively.And the dispersion distribution was more uniform.Finally,from four common organic phases,isopropyl myristate was selected as the oil phase compounded with krill oil,and it was found that it can significantly improve the emulsion instability caused by pure krill oil as the oil phase,and significantly reduce the droplet size of the emulsion growth rate during storage.2.Optimized the PPI concentration,oil phase ratio and emulsification process parameters of Antarctic krill oil emulsion.A single factor experiment was conducted to explore the influence of PPI concentration,oil phase ratio and ultrasonic treatment on the stability of the emulsion system,and the formulation and process were optimized by response surface method.The results showed that the influence of each factor on the response value was PPI concentration> ultrasonic duration> ultrasonic power,and the optimal process parameter conditions are: PPI concentration 4.7%(w/v),ultrasonic power 500 W,and ultrasonic duration 15 min.The krill oil emulsion prepared under these conditions has the highest stability,with a particle size of 6.032 ± 0.008 nm.After being stored for 21 days,the particle size growth rate is only 9.20%.3.Established a hydrogel bead system based on Antarctic krill oil emulsion.The hydrogel beads based on PPI-krill oil emulsion were prepared by the ionic gel extrusion dripping method.Combined with multi-scale characterization methods,the effects of different preparation paraments on the size,microstructure,encapsulation efficiency,stability and in vitro release of the hydrogel beads were investigated.It was found that the diameter distribution of the hydrogel beads embedded with krill oil emulsion were1.03-2.07 mm,and the encapsulation efficiency of the emulsion reached more than 98%.The bead has good interface characteristics,a good hydrogel network structure is formed between the emulsion and the hydrogel bead matrix,has a strong fixing effect on the emulsion,and has excellent stability.In vitro digestion experiments showed that the release rate of the emulsion in the beads is significantly lower than that of the Tween 80 stabilized emulsion hydrogel beads,indicating that the sustained release effect was better.