| The emulsion stability of oat protein(OPI)is not ideal and it can be improved effectively by compounding with polysaccharide,and its application in food field can be expanded.Therefore,OPI and chitosan(CS)were used as raw materials and their interaction mechanism was exploded,OPI-CS composite emulsion was prepared and characterized,the ability of it as a fat-soluble nutrient delivery system was explored.Main research contents are as follows:Firstly,the relationship between turbidity,ζ-potential and particle size of OPI and CS was investigated under different r(OPI: CS)and p H.When r=0.2 and p H 7,the electrostatic interaction between them was strongest,the absolute potential was smallest(-4.29 m V),the turbidity(1.41)and the particle size were largest(128.1±0.11 μm).At r=0.2and p H 4,high concentration of Na Cl inhibited the formation of the complex.At p H 4-5,electrostatic and hydrogen bond interactions are stronger than hydrophobic interactions,and at p H 6-8,electrostatic interactions are stronger.In secondary structure,the amide absorption peak and the stretching vibration zone of the double bond are shifted,andα-helix decreased while β-angle increased,indicating hydrogen bond existed in OPI-CS.In tertiary structure,adding CS improved the hydrophobicity of OPI and changed the spatial structure.The ΔH of ITC at p H 4 is-16.33±2.781 cal /mol,indicating that the binding is exothermic.Secondly,OPI-CS emulsion was characterized.Stability and BS showed that the charge is highest(50.06 m V)and the particle size is smallest(14.49 μm)when r=5:1,and the emulsion stability is best.Over the whole frequency range of 0.5 Pa,G’>G",indicating that its elasticity is much greater than viscosity,shear thinning leads to viscosity reduction,and the internal structure of emulsion is destroyed;When r=5:1 and p H 7,the contact angle closed to 90°,and the adsorption percentage of particle protein at the emulsion interface was 95.32%.Optical images and microstructure showed that the emulsion had good storage property.Finally,β-carotene was embedded in OPI-CS emulsion,and the embedding rate was up to 92.3% when r= 5:1 and p H 7,and the residual rate was more than 90% under the light and heat where β-carotene was easily decomposed.Results of in vitro simulated digestion experiment showed that the release rate of the emulsion with r= 5:1 and p H 7 decreased to27.34% in 2 h simulated gastric digestion with p H 1.2,and the release rate was only49.35% and the bioavailability reached 27.47% after 3 h simulated intestinal digestion with p H 7.4.In conclusion,when OPI-CS compound degree is strong,its emulsion has good stability and can protect β-carotene and other nutrients in light and heat environment,which can be applied in pharmaceutical industry and food nutrition field. |
