Influence of the extrusion parameters on the physical properties of chickpea and barley extrudates

Abstract

In this research, the effects of extrusion processing [exit-die temperature (120-150°C), moisture content (20-24% wet basis), and screw speed (260-340 rpm)] on the specific mechanical energy and physical properties (expansion ratio, bulk density, and hardness) of desi chickpea and hullless barley extrudates were estimated using response surface methodology. Exit-die temperature and feed moisture content, as well as the interaction between them were the factors that affected the product responses the most. Significant correlation was found between the hardness and bulk density (positive), hardness and expansion ratio (negative), and bulk density and expansion ratio (negative) for both chickpea and barley extrudates. Desirable characteristics (high expansion, low bulk density, and hardness) for chickpea were obtained at high exit-die temperature, relatively high moisture, and high screw speed. As for the barley extrudates, high exit-die temperature, low moisture, and moderate to high screw speed were identified as optimal.

Effect of barrel temperature and feed moisture on the physical properties of chickpea, sorghum, and maize extrudates and the functionality of their resultant flours—Part 1

“…HD was also found to increase as moisture increased from 20% to 24%, rising from ~181 to ~201 N and ~173 to ~200 N for sorghum and maize flours, respectively (Table ). Similar results were reported by Yovchev et al (), where temperature, feed moisture, or screw speed had no significant effect on hardness of chickpea (Desi variety) extrudates, but exit‐die temperature was marginally significant ( p < 0.1). However, all three extrusion parameters had a significant effect on hardness for barley, where lower hardness was observed under low moisture, high temperature, and moderate to high screw speed.…”

“…In general, under the same extrusion temperature, the increase in moisture content had a positive effect on ER of chickpea but had a negative effect on the two cereals. This difference in ER in chickpea and cereals was also reported by Yovchev et al () who found an increase in the expansion of chickpea extrudates under higher temperature and moisture, whereas higher expansion of their barley sample was obtained at lower moisture only. The authors proposed that this was a result of the differences in the protein content between the flours.…”

“…Cereal flours underwent a greater amount of expansion (therefore lower BD values) than the chickpea flour due to their higher contents of starch that was responsible for the expansion. The negative correlation of bulk density and expansion, and positive correlation of bulk density and hardness were also reported by Yovchev et al (). The authors found that temperature and screw speed (which were constant in the current study) had a significant effect on bulk density for chickpea, whereas all three factors (temperature, moisture, and screw speed) and their interactions had significant effects on barley.…”

“…The specific mechanical energy (SME) was taken off the control panel of the extruder for each processing run once the values stabilized. The expansion ratio (ER), hardness (HD), and bulk density (BD) were evaluated following the methods of Yovchev, Stone, Hood‐Niefer, and Nickerson (). Measurements for ER, HD, and BD were taken 40, 6, and 6 times, respectively, on extrudates from each processing run and then averaged.…”

Physicochemical properties of ready‐to‐eat extruded nixtamalized maize‐based snacks enriched with grasshopper

“…This may be because increasing the temperature in the barrel decreases the viscosity of the dough required to produce a product of low density, resulting in the formation of small bubbles with thin walls, which results in the production of materials with the lowest values of H (Suksomboon et al, 2011;Navarro-Cortez et al, 2016). Materials with low protein contents (high in starch) tend to form low density inflated-type products, while high-protein materials (low in starch) tend to form products with denser textures (Yovchev et al, 2017). Proteins can have a positive or negative effect on expansion due to their ability to alter the distribution of water within the matrix and based on the type and concentration of protein in the material (Yovchev et al, 2017).…”