Study On Extensively Hydrolyzed Infant Formula Milk Powder And Its Allergenicity

Milk is the main food protein source for infants to replace breast milk,but it is recognized as one of the eight foods causing allergy by the World Health Organization/World Food and Agriculture Organization.The incidence rate of milk protein allergy in infants is 2%-6%,and the main allergen in milk is β-Lactoglobulin,αS1-casein,etc.Enzymes can effectively hydrolyze these proteins to destroy their antigen epitopes,and the enzymatic hydrolysis conditions are mild,the process is simple,and has the advantages unmatched by other methods.It is the main method to produce extensively hydrolyzed infant formula milk powder.In this paper,concentrated whey powder was used as raw material to prepare milk protein powder,so that the composition of casein and whey protein was similar to that of breast milk.The basic physical and chemical properties of extensively hydrolyzed protein prepared by enzymatic hydrolysis of milk protein(in which the ratio of casein to whey protein was 4:6)and its application in milk powder were studied.Finally,the sensitization of extensively hydrolyzed infant formula milk powder was evaluated based on mice model.Milk protein was hydrolyzed by alkaline protease and neutral protease to prepare extensively hydrolyzed protein.The optimum hydrolysis conditions were as follows: time 3h,temperature 50℃,p H 8.5,ratio of enzyme to substrate(E/S)6000 U/g.Compared with the non-hydrolyzed milk protein,the antigenicity reduction rates of β-lactoglobulin and casein in deeply hydrolyzed protein were 34.82% and 31.82%,respectively,the particle size became smaller and more uniform,the water content decreased,the ash content increased,there was no macromolecular complete protein,and the proportion of peptides with molecular weight less than 3000 Da was 97.90%.Scanning electron microscopy showed that the extensively hydrolyzed protein particles were spherical,with a small amount of depressions and folds.According to the general rules of infant formula for special medical purposes(GB25596-2010),extensively hydrolyzed protein was used to prepare extensively hydrolyzed infant formula milk powder.Compared with ordinary cow’s milk infant formula milk powder,extensively hydrolyzed infant formula milk powder had uniform particle size,good preparation performance and slightly bitter taste.The color of the reconstituted milk was light yellow,the texture was slightly thin,the average particle size increased,and the stability was poor.The sensitization of extensively hydrolyzed infant formula milk powder was evaluated by animal experiment.Compared with cow’s milk formula milk powder,the contents of Treg and Th1 cells in the extensively hydrolyzed infant formula milk powder group were significantly increased,while the contents of Th2 cells,serum specific Ig E and Ig G1 antibodies,plasma histamine and serum mast cell enzyme were significantly decreased.The mice in cow’s milk infant formula milk powder group had jejunal erosion,intestinal recess shrinkage,villi swelling,necrosis and shedding,and goblet cell loss.A few blood vessels in the lungs were swollen and congested,and some bronchus were deformed,while the structure of jejunal villi of mice in extensively hydrolyzed infant formula milk powder group was complete,and only a small amount of rupture occurred.The pulmonary alveoli were clean and tidy without foreign bodies and blood vessels were not swollen.The above results showed that the sensitization of extensively hydrolyzed infant formula milk powder was less than that of cow’s milk infant formula milk powder.