DETERMINATION OF PROTEIN FOAM STABILITY FROM TIME-DEPENDENT PRESSURE MONITORING

An apparatus is described for the determination of protein foam stability from time-dependent measurements of the small pressure changes above the collapsing foam in a closed chamber. Experimental data are reported for foams made with a fixed concentration (0.1% wt) of bovine serum albumin (BSA) and various concentrations of the nonionic polysaccharide dextran at neutral pH. The results show a loss of foam stability at low dextran contents, an increase in stability at high contents, and a minimum level of stability at a dextran:bovine serum albumin (BSA) molar ratio of approximately 2. The trends in the data obtained with the new pressure monitoring apparatus are consistent with those obtained by visual observations of the rate of foam volume decay.