Comparative study of functional properties of commercial and membrane processed yellow pea protein isolates

Functional properties of commercial and membrane processed pea protein isolates (PPI) prepared from yellow peas were investigated. Four protein isolates were prepared from yellow pea flour using water and KCl extractions at 25 °C followed by ultrafiltration and diafiltration (UF and DF) at pHs of 7.5 and 7.5 or 6 respectively. Following assessment of compositional attributes; solubility, foaming, flow and dynamic rheology, emulsification ability and heat-induced textural and rheological properties of prepared PPIs and a commercially available PPI were tested and compared. Membrane purification of proteins resulted in 28% to 68% reduction in phytic acid and enhanced, comparatively, the tested functional properties. Solubility of membrane processed PPIs, at all tested pHs, was superior and the lowest foaming stability and apparent viscosity were associated with commercial PPI. Gelling temperatures of water and KCl extracted PPIs, DF treated at pH 6, trimmed down to 75.7 ± 0.63 °C and 81.6 ± 0.55 °C in contrast to that of commercial PPI at above 90 °C. Similarly, the formation of firm gels, after 1 h heating at 90 °C, was associated with membrane processed PPIs whereas commercial PPI did not develop any gel.