Method of modifying lactoalbumin by enzymatic method and its application

[0025] Example 1

[0026] The fresh milk is separated by a centrifuge to remove fat to obtain skim milk. Skim milk is adjusted by ion and heated: Ca is used in the ratio of 1~2:1~2:1 2+ , K + And Na + The solution adjusts the ion concentration to make the pH reach 7.0-7.5; the protein concentration in the solution is 3.1%, heated to 70-90°C through a heat exchanger, maintained for 5-15s, and then cooled to 45-65°C. Immobilized composite enzyme enzymolysis: the enzyme species are papain and trypsin, the ratio of the two enzymes is 4:6, the carrier is sodium alginate, the concentration of sodium alginate solution is 5%, and the enzyme/carrier mass ratio is 1:25. Glutaraldehyde was added dropwise to make the glutaraldehyde concentration in the solution 0.6%, and the reaction was stirred at 35° C. for 10 hours to obtain an immobilized composite enzyme. Enzymatic hydrolysis conditions are: enzyme dosage is 1‰ of milk protein quality, enzymatic hydrolysis at 55℃ for 2.5h, α s -The modification rates of casein and β-lactoglobulin reach 85% and 95% respectively. Then filter to remove the immobilized complex enzyme. The immobilized composite enzyme collected by filtration can be reused more than 20 times.

[0027] Example 2

[0028] The fresh milk is separated by a centrifuge to remove fat to obtain skim milk. Desalted whey powder is added to skimmed milk at a mass/volume ratio of 5%. After ion adjustment and heating treatment: Ca is used in a ratio of 1~2:1~2:1 2+ , K + And Na + The solution adjusts the ion concentration to make the pH reach 7.0-7.5; the protein concentration in the solution is about 3.7%, heated to 70-90°C by a heat exchanger, maintained for 5-15s, and then cooled to 45-65°C. Enzymatic hydrolysis of immobilized composite enzyme: the enzymes are papain and pepsin, the ratio of the two enzymes is 5:5, the carrier is chitosan, the concentration of chitosan solution is 3.5%, and the chitosan should be 1%-2% Dissolve the acetic acid solution, adjust the pH to 7.5 with 6mol/L NaOH, drain and wash with pH 7.5 phosphate buffer, then add the enzyme solution, stir and absorb for 30-40 min, the enzyme/carrier mass ratio is 1:50, Glutaraldehyde was added dropwise to make the glutaraldehyde concentration in the solution 0.8%, and the reaction was stirred at 25°C for 7 hours to obtain an immobilized composite enzyme. Enzymatic hydrolysis conditions are: enzyme dosage is 0.5‰ of milk protein quality, enzymatic hydrolysis at 45℃ for 1h, α s -The modification rates of casein and β-lactoglobulin are 75% and 87%, respectively. The immobilized complex enzyme is removed by filtration.

[0029] Example 3

[0030] The fresh milk is separated by a centrifuge to remove fat to obtain skim milk. Desalted whey powder is added to skimmed milk at a mass/volume ratio of 10%, after ion adjustment and heating treatment: Ca is used in the ratio of 1~2:1~2:1 2+ , K + And Na + The solution adjusts the ion concentration to make the pH reach 7.0-7.5; the protein concentration in the solution is about 4.4%, heated to 70-90°C through a heat exchanger, maintained for 5-15s, and then cooled to 45-65°C. Immobilized composite enzyme enzymolysis: the enzyme species is papain and bromelain, the ratio of the two enzymes is 6:4, the carrier is sodium alginate/chitosan, the concentration of sodium alginate/chitosan solution is 2% (alginic acid) The sodium concentration is 1%, the chitosan concentration is 1%), the enzyme/carrier mass ratio is 1:10, glutaraldehyde is added dropwise to make the glutaraldehyde concentration in the solution 0.3%, and the reaction is stirred at 10°C for 5 hours to obtain Immobilized complex enzyme. Enzymatic hydrolysis conditions are: enzyme dosage is 0.2‰ of milk protein quality, enzymatic hydrolysis at 65℃ for 4h, α s -The modification rates of casein and β-lactoglobulin are 75% and 85%, respectively. The immobilized complex enzyme is removed by filtration.