Effect of high pressure on aggregation and thermal gelation of beta-lactoglobulin

Solutions containing 5% purified beta-Lg B at pH 7.5 were subjected to high pressure treatments of varying intensity and duration. The state of aggreg ation and the thermal gelation properties of the pressure-treated samples w ere monitored immediately after depressurization and after storage for 24 h at 5 degrees C. A pressure of 150 MPa applied for 30 min or pressures in e xcess of 300 MPa applied for 0 or 30 min led to formation of soluble aggreg ates. When continued for 30 min, a pressure of 450 MPa caused gelation of t he 5% beta-Lg solution. The state of aggregation of the protein changed ove r time, generally with an increasing proportion of polymers. For samples me asured after 24 h of storage a good inverse correlation was found between p ressure intensity, proportion of polymers and thermal gelation properties. With increasing pressure, the time of gelation increased and the total gel stiffness decreased.