High-pressure processing of pea protein-starch mixed systems: Effect of starch on structure formation

This work explores the structural effects of high-pressure processing (HPP) on starch in mixed pea protein-starch systems of varying concentrations. Reconstituted pea protein concentrate containing 9, 12, and 15% (w/w) protein, without added starch or in combination with 4 or 8% (w/w) pea starch, respectively, were subjected to HPP at 600 MPa for 4 min, at 5 degrees C. Structural changes were investigated using dynamic rheology, scanning electron microscopy, and differential scanning calorimetry (DSC). The addition of starch enabled the formation of weak gels, at protein concentrations below the minimum required for gelation. Above the minimum protein concentration for gelation, starch addition resulted in stronger gels. Starch acted mainly as a filler in the pressure-induced protein gel matrix, and starch granules remained intact after HPP. DSC analyses confirmed that starch remained ungelatinized after HPP, likely due to the limited availability of water in the mixed systems during HPP. Practical Applications The structure of pressure-induced protein gels can be enhanced by adding starch. Besides being a low-cost ingredient, starch remains ungelatinized after high-pressure treatment, and thus can act like a fiber. Therefore, pressure-treated protein-starch mixtures may lead to the development of low-glycemic index, high-protein products.