Physical characteristics of extrudate from mixed corn grit – red bean flour with treatment of moisture content and extruder barrel temperature

Abstract

Extruded snacks, typically derived from low-protein corn, can significantly benefit from the incorporation of red beans to boost their protein content and enhance overall nutritional value. In this study, the influence of feed moisture content and extruder barrel temperature on various physical attributes of the extruded products, including moisture content, particle density, bulk density, expansion ratio, and hardness, were examined. The snacks were produced using a SYSLG-IV twin-screw extruder with a throughput capacity of 10-15 kg/h. The ingredient composition remained consistent, consisting of a 20% red bean flour and 80% corn grit blend. Three moisture content levels (14%-18%) and three different extruder barrel temperature settings (120°C-140°C) were used as variables. The results demonstrated that both variables significantly impacted the physical properties of the extruded snacks. Specifically, an increase in feed moisture content or a decrease in barrel temperature led to higher moisture content (1.01%-1.82%), greater particle density (0.17 g/cm3-0.39 g/cm3), increased bulk density (0.12 g/cm3-0.32 g/cm3), greater hardness (8.34 N-32.18 N), and reduced expansion ratio (2.17-3.0).