Influence of extrusion conditions on functional and textural properties of brown rice-watermelon seeds extruded snacks

This study aims to evaluate and model the effect of extrusion conditions on the functional and textural properties of brown rice-watermelon seeds extruded snacks. Taguchi was used in designing the experiment and Response Surface Methodology was used to evaluate and model the effect of exit barrel temperature (120 - 140°C), barrel screw speed (300 - 420 rpm), and feed moisture content (16-18%) on water absorption index (WAI), water solubility index (WSI), hardness, chewiness, gumminess, and springiness of the extruded snacks. The Pareto plot was used to evaluate the significant extrusion parameters on the functional and textural properties. The WAI and WSI of the extruded snacks ranged between 2.09 and 2.87 (g/g), and 2.12 and 2.59% respectively. The hardness, chewiness, gumminess, and springiness of the extruded snacks ranged between 118.92 and 4054.40 N, 0.06 and 326.00 N, 2.41 and 1509.17 N, and 0.02 and 0.21, respectively. The Pareto plot showed that exit barrel temperature had the most significant influence on WAI and WSI whereas, the quadratic interaction effect of feed moisture content had the most significant influence on the hardness, chewiness, gumminess, and springiness of the extruded snacks. Polynomial regression models were developed for the functional and textural properties with an adequate coefficient of determination (R2) that ranged from 0.74 to 0.99, thus indicating their ability to predict the properties. Conclusively, a hybrid of Taguchi and Response Surface Methodology (RSM) technique was used to establish and predict the influence of extrusion conditions on the functional and textural properties of brown rice-watermelon seeds extruded snacks.