Development of Gluten-Free Extruded Snack Containing Lentil Flour and Evaluation of Extrusion Process Conditions on...

Increased knowledge about celiac disease and health concerns has generated increased demand for nutritious gluten-free snacks; however, most extruded gluten-free foods remain low in protein and fiber. This study aimed to develop gluten-free extruded snacks with improved nutritional and functional properties using lentil flour (LF) and to investigate the impact of extrusion conditions on the properties of extruded snacks. Extruded snacks were produced using a corotating twin-screw extruder with different ratios of LF to corn grits (CG) (0:75, 25:50, 50:25, and 75:0), with fixed amounts of tomato powder, potato flour, and carrot pomace powder. Two feed moisture (FM) levels (16% and 18%) and three barrel temperatures (BT) (135°C, 150°C, and 165°C) were also investigated. The pasting properties of the flour blends and functional, morphological, sensory, and physicochemical characteristics of the extrudates were assessed. The variation in pasting properties of blends was significant; higher CG content increased paste temperature from 67.0°C to 76.6°C, while LF addition reduced it. Increasing LF and FM negatively influenced the expansion ratio (ER) (3.55-1.55) whereas positively affected apparent density (AD) (0.43-2.63 g/cm³). BT had the opposite effect on AD, with higher BT leading to reduced density. LF and FM significantly affected the texture properties; the hardness increased from 86.72 N to 399.63 N, and the crispness decreased with increasing LF and FM. LF addition increased the a* value, whereas higher BT reduced redness. Additionally, LF exhibited the highest water solubility index (32.53%), while CG had the highest water absorption index (5.39 g/100 g). SEM analysis revealed denser and less expanded formations at higher LF levels. These findings suggest that lentil flour can improve the nutritional and functional properties of gluten-free extruded snacks when the extrusion conditions are adequately controlled. This could offer a viable option for health-conscious consumers and those with gluten intolerance.