Method of preparing casein hydrolysate

A method of preparing a casein hydrolysate for a nutritional composition comprising:

• i. providing a liquid solution comprising casein and endogenous plasmin, wherein the liquid solution comprises at least 90% by weight casein of the total protein content and wherein the liquid solution comprises whey protein in an amount of maximum 10% by weight of the total protein content, and wherein the source of casein and the endogenous plasmin is a milk product selected from the group consisting of a micellar casein isolate (MCI), micellar casein concentrate (MCC), micellar casein retentate (MCR), beta-casein depleted micellar casein isolate, beta-casein depleted micellar casein concentrate, milk protein concentrate (MPC), and microfiltration retentate of a milk product;
• ii) adjusting the pH of the solution of step i) to a pH 7.2 to 9;
• iii) subjecting the pH adjusted solution to a first heat treatment to inactivate microorganisms, wherein the first heat treatment is at a temperature of 85° C. to 180° C. for a period of 0.1 to 30 seconds;
• iv) subjecting the solution of step iii) to a second heat treatment at a temperature of from 25° C. to 45° C. for at least 6 hours to obtain a casein hydrolysate, and
• wherein the method excludes addition of exogenous enzymes.