Effect of incorporation levels of oat and green pea flour on the properties of an extruded product and their optimization

An extruded product was made based on oats and dried green pea using central composite rotatable design. Effects of incorporation level of oat flour (OF, 15.86 to 44.14%) and dried green pea flour (DGPF, 7.93 to 22.07%) on the physical and functional characteristics of extruded products based on composite flour were studied using response surface methodology. Second order polynomial equation was used to describe the effect of OF and DGPF on lateral expansion (LE), bulk density (BD), water solubility index (WSI), water absorption index (WAI), and hardness (HD). Results indicated that OF had negative effect on LE, while positive effect on BD, WSI, WAI, and HD. On increasing DGPF, LE and WSI increased, but it had negative effect on BD, WAI, and HD. Numerical optimization resulted in 41.91% OF and 7.93% DGPF to produce acceptable extrudates. The results suggest that oats and dried green pea flour can be extruded with rice flour and corn flour into an acceptable snack food.