Enhanced gelation of field pea proteins through formation of multicomponent systems using various polysaccharides
The potential for enhanced gelation of globular plant proteins through the inclusion of food-grade polysaccharides was established experimentally for pea protein isolate in combination with ither locust bean gum, guar gum or [kappa]-carrageenan. Both factorial and response surface statistical designs were constructed to screen, optimize and verify physicochemical factors significantly contributing to the gelation of these mixed systems. Design factors included protein concentration, protein to polysaccharide ratio, protein to salt ratio and pH. Evaluation of the elastic (G') and storage (tan [delta]) modulus, acquired from small amplitude oscillatory rheological testing, was used to characterized the resulting networks. Behavior of the bipolymer systems were additionally considered through differential scanning calorimetry and solubility assessment. The addition of guar gum and carrageenan resulted in comparable improvements in pea protein gelation. Improved gelation was not evidenced by the interaction ofthese polysaccharides with pea protein but rather by their incompatibility within solution. Results based on graphical and numerical optimization showed that protein-guar gum systems displayed well-defined gel networks at pHs closer to pea protein's IEP. At a pH of 5.32, protein concentrations could vary anywhere between 11.59 and 28.41% while maintaining protein-polysaccharide ratios below 60.63. Carrageenan improved pea protein gelation at higher alkaline pHs (i.e. pH > 7.70). In such systems however, protein levels above 13.9% and protein-polysaccharide ratios less than 41.30 were necessary. As such when developing a favorable gel from a composite system, guar gum systems demonstrated more flexibility and less restriction in terms of physiochemical parameters (i.e. protein and polysaccharide levels).