Pilot-scale production of hydrolysates with altered bio-functionalities based on thermally-denatured whey protein isolate

Whey protein isolate (WPI) solutions (100gL^-1 protein) were subjected to a heat-treatment of 80°C for 10min. Unheated and heat-treated WPI solutions were hydrolysed with Corolase^® PP at pilot-scale to either 5 or 10% degree of hydrolysis (DH). Hydrolysates were subsequently processed via cascade membrane fractionation using 0.14μm, and 30, 10, 5 and 1kDa cut-off membranes. The compositional and molecular mass distribution profiles of the substrate hydrolysates and membrane processed fractions were determined. Whole and fractionated hydrolysates were assayed for both angiotensin-I-converting enzyme (ACE) inhibitory activity and ferrous chelating capabilities. A strong positive correlation (P<0.01) was established between the average molecular mass of the test samples and the concentration needed to chelate 50% of the iron (CC₅₀) in solution. The lowest ACE inhibition concentration (IC₅₀=0.23gL^-1 protein) was determined for the 1kDa permeate of the heat-treated 10% DH hydrolysate.