Bread-making potential of pea protein isolate produced by a novel ultrafiltration/diafiltration process

Abstract

The incorporation of ingredients like legume flour, concentrate or isolate in cereal-based matrices can lead to the production of nutritionally enhanced products like bread with high protein content. However, many ingredients currently available on the market have a large phytate to protein ratio resulting in reduced protein digestibility and minerals bioavailability. This work aimed to study the potential of supplementing bread with pea protein isolate having a low phytate to protein ratio produced by a novel ultrafiltration/diafiltration (UF/DF) process. Isolate was produced by extracting pea flour in water at room temperature and pH 7.5 followed by purification with UF/DF using 50 kDa hollow fibres membranes. Commercial wheat flour was then substituted at a 10% level (dry basis) with isolate in order to produce bread with protein content over 20%. Flour properties, dough mixing properties and bread characteristics were determined. Supplementing wheat flour with pea protein isolate did not affect damaged starch but slightly decreased falling number. Water absorption was increased for substituted flour while dough stability and development time were not affected. The addition of isolate caused a diminution of the minimum water content for dough formation under continuous water addition. Furthermore, higher maximum torque was observed for the substituted flour with corresponding lower water content at maximum torque. Substitution with pea protein isolate allowed to produce bread with protein content over 20% but induced a decrease in loaf specific volume compared to unsubstituted flour. However, the specific volume of bread substituted with pea protein was maintained over 4g cm-3, which should be considered as satisfactory by the consumers. Flour substituted with low phytate pea protein isolate produced by UF/DF showed a good bread-making potential when compared to unsubstituted flour.