THE FOAMING PROPERTIES OF NATIVE AND PRESSURE TREATED BETA-CASEIN

The potential of high pressure treatment as a method for modification of the foaming properties of beta-casein was studied. The beta-casein was treated at pressures of 300, 600 and 900 MPa for different periods of time. The foaming capacity and foam stability of the native and pr essure treated samples were evaluated. The stability of the foams made with the samples treated at 300 MPa showed a marked improvement in co mparison with native beta-casein. The drainage behaviour and the equil ibrium thickness of the air suspended thin liquid films, measured inte rferometrically, showed some differences between the native beta-casei n and the 300 MPa-treated samples. In particular, samples treated for longer times (30 min) displayed a decrease in the rate of film thinnin g and a larger equilibrium film thickness. The effect of the addition of the competitive surfactant Tween 20, was studied. High pressure tre atment of the beta-casein restricted the disruptive action of Tween 20 to a highly significant extent.