Study On The Mechanism Of Casein In The Reconstruction Of Milk Fat Globule Membrane

Dairy products have high nutritional value,functional characteristics and refreshing taste,as people's living standards improved,it has been favored by consumers.But in the storage process,fat is unstable,prone to fat floating,seriously affecting consumer acceptance and the desire to buy.The stability of the milk system is closely related to the fat globule membrane.The stability of the fat globule membrane mainly depends on its structure and composition.Homogenization and other processing conditions will cause the re-construction of the fat globule membrane.In the process of re-construction of fat globule membrane,casein,as the main membrane material in milk system,will adsorb on the surface of fat globules and form new fat globule membranes to maintain the stability of the reconstructed system.Therefore,the change of casein in the process of re-construction of fat globule membrane will affect the stability of milk system.The purpose of this paper is to study the changes of binding modes,components and contents of casein in fat globule membrane under different homogeneous pressures and different fat contents,and to explore the effect of casein on the stability of milk system.On this basis,the high oil whey powder was developed.The effect of casein on the stability of the system was verified in the high oil whey powder system.By SDS-PAGE gel electrophoresis,the combination of casein and fat globule membrane in milk system was mainly divided into three types:indirect adsorption on the surface of fat globule in the form of casein micelles,directly adsorbed on the surface of fat globules,,combined with protein on the surface of fat globule by covalent bond.In the form of casein micelles indirectly adsorbed on the surface of the fat globule accounted for the vast majority.And the higher the homogenization pressure and fat content,the more casein was involved.It was found by Nitrogen Kjeldahl method that with the increase of homogenization pressure and fat content,the interfacial protein content of fat globule membrane increased gradually,and the casein micelle adsorbed on the surface of fat globule also increased gradually.It was found by liquid chromatography-mass spectrometry that asi-casein and K-casein decreased with the increase of homogeneous pressure,and ?s2-casein and ?-casein increased with the increase of homogenization pressure.Through the temperament detection and multivariate equation,the formula of blending oil was obtained:corn germ oil 8%,rapeseed oil 45%,soybean oil 47%.By measuring the stability coefficient and particle size,the optimum preparation technology of high oil whey powder was as:homogeneous pressure 35 MPa,emulsifying temperature 80? emulsifier addition 1.25%,emulsifier ratio 3:1(monoglyceride:sucrose ester).By measuring the stability coefficient and physical and chemical properties,the spray-drying conditions were obtained:the shape content was 30%,the inlet air temperature was 180?,and the outlet air temperature was 90-100?.By measuring the effect of sodium casein content on the high oil whey powder system,it was found that:when the content of sodium caseinate was 10%,the stability coefficient TSI was the smallest,the particle size of emulsion was the smallest,the surface oil content was low,whey powder granules were round and full,and the shape was relatively good.