Rehydration and water sorption behaviour of bovine milk protein isolate and its associated enzymatic hydrolysates
Year: 2022
Journal: Int. Dairy J., Volume 128, MAY
Authors: Ryan, Ger; O'Regan, Jonathan; FitzGerald, Richard J.
The glass transition temperature (T-g), moisture sorption and rehydration properties of bovine milk protein isolate (MPI) and MPI hydrolysates generated with Flavourzyme (TM), Neutrase (TM) and Protamex (TM) [degree of hydrolysis (DH) ranging from 15.6 to 37.1%] were evaluated. MPI hydrolysates displayed reduced water droplet contact angles (<50 degrees) compared with intact MPI (similar to 90 degrees), indicating increased wettability. The aqueous solubility of the hydrolysates was increased (72-100%) compared with intact MPI (similar to 30%) at 25 degrees C. The hydrolysates had higher moisture contents (40-50%) than intact MPI (similar to 27%) at water activity (alpha(w)) values between 0.80 and 0.90. MPI hydrolysates displayed reduced T-g (48.5-67.3 degrees C) compared with intact MPI (-121 degrees C), indicating reduced stability. Overall, enzymatic hydrolysis enhanced the properties of MPI; this improvement was enzyme dependent and increased with increasing DH. Manufacture of hydrolysate ingredients with a controlled moisture content and storage at controlled ambient temperatures is proposed to maintain the improved rehydration properties. (C) 2022 Elsevier Ltd. All rights reserved.
