EFFECTS OF PROCESSING TECHNIQUES (BLANCHING, SOAKING AND OVEN DRYING) ON THE QUALITY ATTRIBUTES OF PAP FLOUR FROM SORGHUM AND PIGEON PEAS
Abstract
This study evaluated the proximate composition, functional properties, antinutritional factors, and sensory acceptability of pap flour and gruel produced from fermented sorghum partially substituted with pigeon pea flour subjected to different processing methods. Four formulations were prepared: Sample PP1 (100% fermented sorghum), Sample PP2 (90% sorghum + 10% blanched pigeon pea), Sample PP3 (90% sorghum + 10% soaked pigeon pea), and Sample PP4 (90% sorghum + 10% oven-dried pigeon pea). Standard analytical methods were used for chemical, functional, and antinutrient determinations, while sensory evaluation was conducted on pap gruel using a 9-point hedonic scale. Proximate composition varied as follows: moisture 4.46–5.95%, protein 3.72–10.64%, fat 1.41–2.11%, ash 1.81–2.60%, fibre 1.54–3.46%, and carbohydrate 75.25–87.06%. Functional properties varied with formulation: bulk density 0.54–0.84 g/ml, water absorption capacity 3.72–4.82 g/g, swelling capacity 1.34–2.62 g/g, and gelatinization temperature 58.40–67.60°C. Antinutritional factors showed slight reductions with pigeon pea inclusion: saponin 14.12–15.96 mg/l, tannin 8.04–8.30 mg/l, while trypsin inhibitor activity remained relatively stable at 77.05–77.77 mg/l. Sensory scores of pap gruel were high across all samples: appearance 8.1–9.0, taste 7.6–8.8, consistency 7.8–8.9, mouthfeel 7.6–8.9, and overall acceptability 7.7–9.0. The control sample PP1 scored highest in sensory attributes, while blanched (PP2) and soaked (PP3) blends maintained good acceptability. Oven-dried PP4, though nutritionally dense, was rated lowest in overall preference. The study concluded that partial substitution of sorghum with pigeon pea flour improved the nutritional and functional properties of pap, with blanched and soaked pigeon pea blends (PP2 and PP3) producing the most balanced formulations in terms of nutrient enrichment and sensory acceptability.
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