Optimization of Process Variables for Extruded Snacks from Acha-Peanut Blends Separately Enriched with Carrot and Orange-Fleshed Sweet Potato Flours

Abstract

Extruded foods are shaped, cooked products made by forcing ingredients through a high-temperature, high-pressure extruder. This study optimized extrusion conditions for snacks made from acha-peanut blends enriched with carrot and orange-fleshed sweet potato (OFSP) flours. Using material balancing, four formulations were developed to meet a 19 g/day target: A (100% acha), AP (81.08% acha + 18.92% peanut), APC (64.21% acha + 20.64% peanut + 15.15% carrot), and APO (64.55% acha + 20.74% peanut + 14.71% OFSP). A two-level factorial Central Composite Design was employed to study the influence of moisture (14–22%) and temperature (100–120 °C) on the physical characteristics and acceptability of the snacks. Results indicated that 100% acha (A) snacks had the largest diameters (13.3–14.9 mm) and lowest densities (apparent: 0.41–0.54 g/ml; bulk: 0.13–0.17 g/ml), leading to high porosity (0.68–0.80), expansion ratios (4.43–4.97), and overall acceptability (6.85–8.25). AP snacks exhibited slightly smaller diameters (12.7–13.9 mm), higher densities (apparent: 0.46–0.60 g/ml; bulk: 0.13–0.21 g/ml), moderate expansion ratios (4.23–4.67), and acceptability scores (7.50–8.00). APC snacks had increased densities (apparent: 0.54–0.60 g/ml; bulk: 0.16–0.28 g/ml), smaller diameters (9.5–11.7 mm), lower porosity (0.53–0.71), and reduced expansion ratios (3.17–3.90), with acceptability scores (6.55–8.15). APO snacks yielded the densest snacks (apparent: 0.60–0.71 g/ml; bulk: 0.29–0.41 g/ml) with the smallest diameters (7.9–9.0 mm), lowest expansion ratios (2.63–3.00), and the least acceptability (6.50–8.10). Regression analysis indicated that higher moisture content decreased density and acceptability, while increased temperature enhanced porosity and expansion especially in AP and APO snacks. Optimal extrusion conditions were identified as: A (14.57% moisture, 113.33 °C), AP (19.90%, 120 °C), APC (18.93%, 118.79 °C), and APO (17.72%, 113.94 °C). Further studies are suggested to evaluate the quality and shelf-life stability of the optimized products.