Kinetic parameters for high-pressure-induced denaturation of lactoferrin in human milk

Abstract

The effect of high pressure and heat treatment of human milk on denaturation of lactoferrin was studied. The degree of protein denaturation was estimated using a sandwich enzyme-linked immunosorbent assay. Kinetic parameters for pressure-induced denaturation of lactoferrin were determined over the pressure range 300–650 MPa at 20 °C. Treatment at 300, 400, 500 and 600 MPa for 15 min denatured 9%, 23%, 34% and 48% of lactoferrin, respectively, whereas treatment at 65 °C for 30 min denatured 80%. Pressure-induced denaturation of lactoferrin followed a reaction order of n = 3. Values for the denaturation rate constant ranged from 1.9 × 104 s−1 at 300 MPa to 58.0 × 104 s−1 at 650 MPa. Heat-induced denaturation of lactoferrin involved protein aggregation by disulphide bonds; covalent interactions did not occur during pressure treatment. Results suggest that high-pressure processing is a potential alternative to thermal pasteurisation, giving greater retention of native lactoferrin.