For systems containing PPI, the reduction in overrun is linear
when present along with H.T starch, whereas the OSA systems
reduce the overrun dramatically (by 50%) when present at concentrations
of 3wt%. The surface tensions corresponding to the
PPI systems are more erratic (Fig. 4b and d), although OSA1 and
OSA2 systems observe an overall increase in s with increasing
concentration, which is reflected in the lowering of PPI system's
overrun Fig. 4b. The poor performance of these systems can be attributed to the fact that at higher pH above their iso-electric
point, pea globulins are not completely dissociated (Gharsallaoui
et al., 2009), so that less surface-active groups are less available
for adsorption.