A Simplified Method for Determination of Browning in Dairy Powders

An improved method for the determination of nonenzymatic browning in dehydrated dairy powders is described. The method involves liberation of the brown pigments from the protein molecules by means of a proteolytic enzyme, pronase. For complete proteolysis, the pronase mixture (2.53 mg enzyme/U.lg dry powder) was incubated at 45°C for 2 hr. After clarification, the browning index (defined as the optical density difference measured at 420 nm and 550 nm) was determined spectrophotometrically. The suggested method proved to be straightforward, easy to employ, and showed high accuracy and reproducibility. The procedure is suitable for routine laboratory analyses and its repeatability, as expressed by the coefficient of variation, was below 3%.