Physical characteristics of extrudate with treatment composition ratio of mixed corn grit-soybean flour and extruder barrel temperature

Abstract

Yellow corn is one of the key component in the production of popular RTE snacks. However, corn's nutritional quality is relatively low, necessitating the incorporation of additional ingredients such as soybean to enrich the protein content. This study primarily aims to explore the influence of soybean flour composition and temperature of barrel on the physical characteristics of extrudates to produce nutrition-rich snacks. The materials utilized in the experiment consisted of corn grit (mesh 24) and soybean flour (mesh 80). Extrudates were produced using SYSLG twin-screw extruder machine with a 10-15 kg/h production capacity. The study's experimental design employed two factors: the composition factor of soybean flour (at 10%, 20%, and 30%) and the final temperature of the barrel (at 120°C, 130°C, and 140°C). The physical attributes of the extrudates were assessed based on the parameters such as expansion ratio, extrudate texture (hardness), moisture content, WAI, and WSI. The study findings revealed that increased soybean flour composition reduced the expansion properties and a more rigid material texture. On top of that, all extrudates exhibited moisture content of less than 4% (wb). The water absorption index decreased with higher soybean flour composition and barrel temperature, whereas the water solubility index showed an increasing trend. Among the tested conditions, the treatment with temperature of the barrel of 140°C and a soybean ratio of 20% demonstrated the best quality results.