This study investigated the effect of partially substituting corn semolina (CS) with mung bean flour (MBF) (20%–60%) as well as feed moisture (FM) (16%–20%) and extruder barrel temperature (BT) (140°C–170°C) on the physicochemical, functional, sensorial, and morphological properties of extruded snacks. Additionally, the pasting properties of MBF, CS, and the blends employed in the formulations were studied. The addition of 40% MBF to the formulations resulted in a decrease in the peak viscosity, while the addition of 60% MBF increased it. The final viscosity and setback viscosity exhibited a decrease, while the breakdown viscosity showed an increase with the addition of MBF. The degree of crystallinity, expansion ratio, apparent density, hardness, crispiness, water solubility index, and morphology of the extrudates were strongly dependent on the MBF content, FM, and BT. The expansion ratio and crispiness of the extruded products decreased with increasing MBF content, BT, and FM. The increase in BT and decrease in FM reduced the degree of crystallinity of the extrudates. Analysis of the microstructure revealed that the addition of MBF increased the thickness of the extrudate cell walls and reduced the size of air cells. The size and expansion of the air cells also decreased with increasing FM. Based on our study, the optimal conditions for the MBF-containing snacks were determined as 143°C BT, 16% FM, and 40% MBF. Notably, the MBF-containing snacks exhibit lower starch digestibility compared to the MBF-free sample; the latter exhibited a higher degree of anisotropy, indicating a higher-organized structure.

Practical application

The use of mung bean flour (MBF) as a substitution for corn semolina and the effects of feed moisture (FM) and barrel temperature (BT) in extruded snack production were studied. The results showed that MBF is a promising ingredient for enhancing the functionality and nutritional value of extruded snacks. The expansion ratio, apparent density, hardness, crispiness, water solubility index, crystallinity, and morphology of the extrudates were significantly dependent on MBF amount, FM, and BT. The expansion ratio and crispness of the snacks decreased with the increase in the MBF amount, BT, and FM. The addition of MBF to the formulation was appreciated by the panelists. The MBF enhances the quality characteristics of the snacks and decreases starch digestibility. The findings of this study provide a reference for the impacts of extrusion parameters on the production of high-protein content snacks.