Study On Production Of Hypoallergenic Milk By Biological Methods

Milk contains a variety of essential amino acids which were needed by the human and a source of high quality protein.Meanwhile,the vast majority of milk proteins have potential allergens.Of them ?-LG not contained in human milk is considered as the major allergen.in this study,skim milk were treated with biological methods such as protease hydrolysis and Lactic acid bacteria fermentation).to lower the allergenicity.p-LG inhibition rate was detected by ELISA,which can indirectly reflect milk allergenicity.then the most suitable conditions for production of hypoallergenic milk with protease hydrolysis and Lactic acid bacteria fermentation were studied in more detail.Three kinds of different proteases with neutral pH were uesd to hydrolyze skim milk.The degree of hydrolysis(DH)4%as criterion,the most suitable conditions for producing hypoallergenic milk with proteases(trypisn,neutral protease,papain)were determined respectively:the temperature 40?,45?,55?,enzyme concentration 1600U/g protein,1770U/g protein,2400U/g protein and hydrolysis time 0.5h,1.1h,0.9h.Single protease hydrolysis study showed that,the most suitable proteasefor producing hypoallergenic milk is trypsin,when skim milk was hydrolyzed,for 3h,the highest ?-LG inhibition rate detected by ELISA was 48.41%,and the hydrolysate had the least allergens.Therefore,trypsin is selected as the main protease,neutral protease and papain are as auxiliary proteases,which were uesd to double enzyme hydrolysis study.Study showed that the degree of hydrolysis(DH)4%as criterion,double enzyme system consisting of trypsin and papain was the optimal system,their most suitable hydrolysis conditionswere temperature 45?,enzyme concentration 1600U/g protein,the ratio 2:1.when skim milk was hydrolyzed under the most suitable condition of trypsin and papain for 3h,the highest ?-LG inhibition rate detected by ELISA was 53.91%,and the hydrolysate has the least allergens.Lactic acid bacteria fermentation study showed that hypoallergenic milk can be produced by,fermentation with double strains(Streptococcus thermophilus 6038 and Lactobacillus bulgaricus 6047).Taking the viable count,pH,?OD340 of fermented milk as criterion,the most suitable fermentation conditions for producing hypoallergenic milk with double strains were temperature 42?,inoculated amount 3%,inoculated proportion 1:1.When skim milk was fermented under the most suitable fermentation condition,for 20h,the highest?-LG inhibition rate detected by ELISA was 37.87%,andthe hydrolysate has theleast allergens.These results suggest that protease hydrolysis has a more abvious effect to reduce the allergenicity comparing with Lactic acid bacteria fermentation.