Effects of heating and pressurization on foaming properties of beta-lactoglobulin

The effects of heating (80oC/10 min and 90oC/2 min) and pressurization (300, 600 and 900 MPa for 10 min and 300 MPa for 10 to 30 min) on foaming properties of beta-lactoglobulin (beta-Lg) obtained from whey retentate in mild conditions were compared in the pH range of 5.0 to 7.0. Generally, heating and pressurization improved the beta-Lg foamability, except that at pH 7.0 (1) heating of the protein worsened (80oC/10 min) the foaming properties or not changing (90oC/2 min) the foam capacity - improved the foam stability and (2) pressurization at above 300 MPa drastically worsened the foam stability (600 MPa) or caused that the foam was unstable (900 MPa). The highest foam capacity had beta-Lg pressurized for 10 min at 300 MPa in pH 7.0 and lengthening of the pressurization time up to 30 min resulted in the increase in the foam stability with the foam capacity being practically unchanged.