Effects of alkalinization and addition of pea protein as a co-protein to zein for the development of gluten-free doughs

The effects of adding pea protein isolate (PPI) as a co-protein to calcium hydroxide deamidated zein were evaluated by fundamental rheological properties of gluten-free doughs measured at room temperature and FT-IR. Rice starch was used as a carbohydrate source at a constant concentration. Gluten-free doughs prepared with PPI, PPI + zein, zein under alkaline conditions, and PPI + zein under alkaline conditions were compared with a control sample containing gluten. Small and large deformation rheological tests indicated that the combination of PPI and the alkaline treatment of zein improved the gluten-free rheological properties, leading to a similar rheological performance to the control containing gluten. The sole addition of PPI to zein, or the alkaline deamidation of zein alone, did not generate doughs with desirable rheological behaviors. Quantification of the different conformations of the protein's secondary structure by FT-IR analysis confirmed that better rheological properties of dough containing PPI and zein under alkaline conditions are associated with higher amounts of beta-sheets conformations. The use of zein is often limited to temperatures above its glass transition temperature (approximate to 28 C-degrees), but the results from this study provide important insights for the application of zein at room temperature in gluten-free doughs.