Enzymatic modification of milk protein concentrate and characterization of resulting functional properties

Milk protein concentrates are suitable ingredients for high-protein beverages, but are underutilized due to poor solubility at ambient temperature and neutral pH. The other functional properties of milk protein concentrate, such as emulsification and foaming, depend on its solubility. Milk protein concentrate with 80 g protein 100 g(-1) was hydrolyzed with three digestive enzymes - chymotrypsin, trypsin, and pepsin - and one cysteine protease - papain - to improve solubility and functionality. Two hydrolysates were produced with each enzyme at targeted levels of hydrolysis to help prevent the development of bitterness. Reduced urea sodium dodecyl sulfate polyacrylamide gel electrophoresis showed that casein subunits were more susceptible to hydrolysis compared with the whey proteins. Enzyme hydrolysis improved the solubility of the milk protein concentrate in the pH range of 4.6-7.0 inclusive. All enzyme hydrolysates had reduced surface hydrophobicity and gel strength. Hydrolysis with chymotrypsin and trypsin improved emulsion activity and stability whereas emulsification capacity was improved with all enzymes. Foaming properties depended on enzyme and hydrolysis time. The hydrolysis of milk protein concentrate with food enzymes can improve solubility and alter resultant functional properties. (C) 2013 Elsevier Ltd. All rights reserved.