Harnessing underutilized food crops for sustainable extruded snack production: a scoping review.

Extruded snacks are primarily made from staple cereals. Incorporating underutilized crops can enhance their nutritional value and diversify ingredient supply. Quinoa, Bambara groundnut, orange-fleshed sweet potato (OFSP), and sesame seed are promising candidates, although evidence on their performance in extruded snack products is dispersed across product formats and outcome characterization. This scoping review was conducted to map peer-reviewed studies published from 2000 to 2026 on extruded snack products containing quinoa, Bambara groundnut, OFSP, or sesame seeds. Searches were conducted in Web of Science, Google Scholar, and ResearchGate databases, followed by deduplication and screening of the results. Data charting captured ingredient form and inclusion, extrusion conditions, and outcomes, including expansion and density, hydration indices, texture, color, sensory acceptance, nutrition-related endpoints, antinutritional factors, and shelf-life indicators. Of the 405 records retrieved, 42 studies were included. Quinoa-based snacks were the most frequently studied, and expansion indices, bulk or unit density, water absorption index (WAI), water solubility index (WSI), and instrumental texture were the most often reported. Bambara groundnut studies commonly target protein enrichment and use mixture or response surface designs to relate formulation and process variables to expansion, density, and hydration indices, with limited but informative storage quality data. OFSP studies prioritized provitamin A endpoints alongside expansion, color, texture, and acceptability, with measurable processing losses reported in several product formats. Sesame seed studies emphasized lipid-rich ingredients and reported consistent reductions in expansion with increasing inclusion, while offering stronger coverage of oxidative stability during storage through peroxide and acidity values. Across crops, sensory evaluation, shelf-life, microstructure imaging, antinutritional factors, and protein quality parameters were reported less consistently than physical structure metrics, and energy-based process descriptors were infrequently provided. Research supports the feasibility of these underutilized crops in extruded snack systems; however, translation is constrained by uneven outcome coverage and inconsistent reporting of extrusion severity. Future studies should report processing severity descriptors more consistently and align findings with crop-specific targets, including provitamin A retention for OFSP, oxidation management for sesame seed-enriched snacks, and standardized structure-texture-sensory linkages across formulations.