Gelation Behavior of Protein Isolates Extracted from 5 Cultivars of Pisum sativum L.

ABSTRACT: Protein isolates were extracted from 5 pea ( Pisum ) cultivars and their gelation behaviors were compared at pH 7.6. Gel formation and development was monitored via constant oscillation dynamic measurements. The standard heating and cooling rate was 1.0°/min, but samples were also heated at 0.5°C (and cooled at 1.0°C/min), and others were heated at 1.0°C/min and cooled slowly at 0.2°C/min. When heating more slowly, no changes in gel formation were detected for any of the cultivars. When cooling slowly, the cultivar Solara, with the highest legumin content, formed a stronger gel than all the other cultivars. It did the same when the thiol-blocking agent N -ethylmaleimide (NEM) was added to the system. This indicated that the strengthened gel system formed independently of any disulfide bonds formed by the legumin. The cultivars Supra and Classic formed stronger gels only when cooled slowly in the presence of NEM, and so disulfide bond formation in their gel systems was apparently a factor that prevented gel network strengthening. The cultivars Finale and Espace were unable to form strong and self-supporting gels. This was believed to be because of the repulsive forces on the α-subunits of vicilin, which were at their highest level in the cultivars Finale and Espace. The contribution of legumin to the pea protein isolate gels was shown to be cultivar specific and related to its disulfide bonding ability rather than the absolute amount of legumin protein present.