EFFECT OF DEHULLING METHODS AND PARTICLE SIZE ON THE NUTRITIONAL, MINERAL, FUNCTIONAL AND SENSORY PROPERTIES OF COWPEA AKARA

The preparation of cowpea flour Akara traditionally involves a wet dehulling method where cowpea seeds are soaked, the seed coats are manually removed, the cotyledons are ground into a paste, and then the paste is fried. However, using different methods for dehulling and milling may affect the product's nutritional value and sensory attributes. Thus, the aim of this study was to assess the proximate composition, some minerals, functional properties, rehydration kinetics, particle size distribution, and sensory attributes of cowpea flour Akara made from cowpea flour that was dehulled and sieved differently (mechanical and hydrated dehulling, and sieves of 150 µm, 300 µm, 425 µm). 6 formulations of the Akara were prepared from cowpea flour: Sample MA (mechanical, 150 µm), Sample MB (mechanical, 300 µm), Sample MC (mechanical, 425 µm), Sample CA (conventional, 150 µm), Sample CB (conventional, 300 µm), Sample CC (conventional, 425 µm). Proximate, mineral, functional, and particle size distribution analyses were done using standard methods, while a sensory analysis using a 9-point hedonic scale was conducted. Proximate analysis revealed moisture content of 32.59–43.08%, protein 8.19–11.33%, fat 9.95–16.51%, fiber 0.74–1.31%, ash 2.01–2.87%, and carbohydrates 31.40–37.51%. For all the minerals, content was progressively increasing with conventional dehulling and smaller particle sizes: calcium 26.03–52.66 mg/100 g, magnesium 15.55–36.69 mg/100 g, and sodium 462.00–586.74 mg/100 g. Functional properties including bulk density, water absorption capacity, oil absorption capacity, foam capacity, and dispersibility, and wettability showed significant differences (p < 0.05): bulk density 0.64–0.77 g/ml, water absorption capacity 95.71–136.94%, oil absorption capacity 88.37–94.83%, foam capacity 23.02–36.03%, dispersibility 61.00–71.50%, and wettability 50.50–95.00 s. Rehydration characteristics differed among the samples with rehydration ratio and time ranging from 0.90–1.73 and 24.00–30.00 min, respectively. Particle size distribution varied across samples, with 33.80% recovery for mechanically dehulled cowpea flour and 18.70% for hydrated and dehulled cowpea flour. The sensory scores for all of the cakes were high with sample MA getting the highest overall score and sample CB having the lowest score for taste, with scores for appearance at 7.75–8.40, for taste at 7.45–8.25, for flavour at 7.55–8.20, for texture at 7.15–8.10, and for overall acceptability at 8.05–8.50. The study showed strong evidence that cowpea dehulling and subsequent particle size reduction are both of critical importance for the nutritional, functional, and rehydration characteristics of cowpea flour and akara, with sample MA representing the best balance of improved nutrition, functional properties, and consumer acceptance.