Improved Method for Determining Food Protein Degree of Hydrolysis

ABSTRACT When producing hydrolyzed proteins, it is important to determine the degree of hydrolysis (DH). The trinitro‐benzene‐sulfonic acid (TNBS) method is well established with regard to enzymatic hydrolysis. However, this method is laborious, cannot be used to follow a hydrolysis reaction continuously, and includes hazardous and unstable chemicals. This paper describes a method based on the reaction of primary amino groups with o‐phthaldialdehyde (OPA). The conclusion is that the OPA method of analyzing the DH of protein hydrolyses is more accurate, is easier and faster to carry out, has a broader application range, and is environmentally safer than the TNBS method.