Multivariate evaluation of nutritional, techno-functional, and structural properties of wheat-mopane worm (Gonimbrasia belina) composite flours

Abstract

The rising global demand for sustainable, nutrient-dense protein sources has renewed focus on edible insects such as Gonimbrasia belina (mopane worm). This study investigated the impact of mopane worm powder (0 - 30% inclusion) on the nutritional, techno-functional, thermal, and structural properties of wheat-based composite flours. The protein content increased significantly (p < 0.05) from 16.4% in the control flour to 24.9% at a 30% substitution, confirming its potential as a high-quality protein alternative. Colour attributes revealed a decrease in lightness (L*) from 88.37 to 74.24 and an increase in redness (a*) from 0.56 to 1.50, reflecting a visible darkening with insect incorporation. Mopane worm powder exhibited the highest water-holding (2.5 g/g) and oil-holding capacity (2.7 g/g), surpassing that of wheat flour. Rapid Visco Analyzer (RVA) analysis revealed a marked reduction in peak viscosity (from 2050 cP to 980 cP), with final viscosity and setback values declining by 45% and 60%, respectively, indicating diminished starch retrogradation. Thermogravimetric analysis (TGA) demonstrated improved thermal stability, with mopane worm powder degrading at 285 °C compared to 250 °C for wheat. FT-IR spectra displayed intensified amide I (1650 cm⁻¹) and II (1540 cm⁻¹) bands, along with aliphatic and chitin-associated peaks, corroborating the enrichment of proteinaceous and lipid components. Principal Component Analysis and Hierarchical Cluster Analysis revealed clear sample clustering by inclusion level, with protein, colour, and techno-functional properties driving variance among the mopane-enriched composite flours. The incorporation of mopane worm powder significantly improved the nutritional profile, thermal stability, and structural matrix of wheat-based flours, underscoring its potential as a sustainable bio-ingredient for protein-energy malnutrition interventions within climate-resilient food systems.