Effect Of Milk Fat Globule Membrane Protein On The Fat Stability Of Infant Formula Powder

By-products produced during milk-fat processing contain abundant milk fat globule membrane(MFGM)and are considered as sources of MFGM proteins.Previous studies have done a lot of in-depth analysis on the separation process and functional characteristics of MFGM protein.But mentioned separation methods are not suitable for the industrial production of MFGM protein products.In this paper,LS-MS/MS was used to evaluate MFGM protein enriched products derived from by-products during different stages of milk fat processing.Then the best raw material for commercial membrane protein products was chosen and applied to infant formula powder.The effect of MFGM protein on fat stability of infant formula powder was studied.Finally,the fat properties of infant formula with the best stability were compared with those of nine kinds of infant formula sold in the market.Five groups of products rich in MFGM protein were collected from different processing stages by simulating the industrial production process of cream,butter and anhydrous milk fat.The proteomics analysis of these products was carried out by LS-MS/MS.Samples obtained after phase inversion showed higher number of total protein and differential protein,and higher concentration of major MFGM proteins.Both the number and the concentration in samples collected after phase inversion increased with the fat content of cream.The LC-MS/MS results also showed the different distribution of MFGM proteins in samples collected from different processing stages,which may be caused by the asymmetric distribution of proteins on the membrane.The content of major MFGM proteins in the samples separated from skimmed milk was little.The buttermilk derived from cream with 14.62%fat could be the raw material for separating and purifying PP3;The buttermilk derived from cream with 41.33%fat was the best raw material for glycoprotein 2;Butter serum was the best raw material for the separation of intact MFGM protein product.The MFGM protein enriched product isolated from butter serum was added to infant formula.Proper amount of MFGM protein could reduce the size of fat globules,which protected against fat aggregation and promoted the fat stability.On the other hand,the addition of membrane proteins promoted the encapsulation of fat globules in the re-construction of MFGM,which formed a stable space layer and improved the fat stability.However,too higher content of MFGM protein had a negative effect on the stability of infant formula.When the addition amount was 1.6%,fat physical stability in infant formula was the best.By comparing the stable self-made infant formula with nine kinds of infant formula sold in the market,it was found that the addition of membrane protein could decrease the particle size of fat globule,improve the physical stability and oxidation stability of fat In addition,the results also showed there was a certain correlation(positive correlation,R2-0.86)between the size of fat globules and the TSI value of fat in infant formula,and a certain correlation(positive correlation,R2=0.92)between the content of free fat and the size of fat globules,and a certain correlation(positive correlation,R2=0.96)between the total oxidation value and the content of free fat.