Effect of Extrusion Parameters on Nitrogen Solubility Index of Fonio-Locust Powder Extrudates
DOI:
https://doi.org/10.33003/fjs-2026-1012-5300Keywords:
Fonio, edible locust powder, extrusion, nitrogen solubility index, protein functionality, thermo mechanical processing, sustainable proteinAbstract
This study evaluated the influence of extrusion processing variables on the nitrogen solubility index (NSI) and compositional quality of protein-enriched fonio–edible locust powder extrudates. A three-factor, five-level central composite rotatable design was employed to assess the effects of edible locust powder inclusion, screw speed and barrel temperature on extrudate functionality. Fonio flour and edible locust powder blends were conditioned to 20% moisture content and processed using a co-rotating twin-screw extruder at barrel temperatures of 96.36–163.64°C, screw speeds of 98.87–351.13 rpm and locust powder inclusion levels of approximately 3.6–36.7%. Proximate composition and NSI were determined using standard analytical procedures, with NSI evaluated at pH 3.5, 7.0 and 9.0. Protein solubility exhibited a distinct pH-dependent U-shaped pattern, with minimum NSI at pH 7.0, intermediate solubility at pH 3.5 and maximum solubility under alkaline conditions at pH 9.0. NSI ranged from 25.36% to 60.29% at pH 3.5, 14.51% to 42.34% at pH 7.0 and 40.30% to 79.05% at pH 9.0. Response trends showed that moderate extrusion severity preserved protein dispersibility, whereas excessive screw speed and high thermo mechanical input promoted protein aggregation and reduced its solubility. These findings demonstrate that extrusion parameters can be strategically controlled to balance protein enrichment, texturization and functional protein recovery in fonio–insect-based snack systems, while supporting the development of sustainable, high-protein extruded foods from underutilized cereals and edible insect ingredients
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Copyright (c) 2026 Lois Onyedika, Kuyik Solomon Abasiekong, Maduebibisi Offor Iwe
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