ABSTRACT

Cormels of cocoyam (Colocasia esculejita, var. cocoinclici) and soybeans (Glycine max) were each cooked, dried and milled into flour of line texture, and combined with dried crayfish (a crustacean of the order Decapoda) flour to prepare cocoyam-soybean-crayfish composite flours in the ratios 80:15:5, 70:25:5, 60:35:5, and 50:45:5. The composite flours were used as base for production of rat diets and complementary foods. The composite flours were subjected to proximate analysis, evaluation of physical, functional, and amylograph pasting properties, sensory evaluation, anti-nutritional factors analysis and storage stability trials in lidded metallic containers and screw-capped plastic containers at 26,5±0.3°C and 70.8± 4.5% relative humidity. The complementary foods were also stored under similar conditions and total microbial count and organoleptic characteristics were periodically determined. Feeding tests using albino rats were carried out and the response of the rats to the diets was determined. Proximate analysis of the composite flours showed that the flours were nutritively adequate in protein (ranged from 11.90% to 20.70%), carbohydrate (ranged from 52.03% to 67.60%), fat (ranged from 4.20% to 11 .13%), ash or mineral (ranged from 4.60% to 5.60%), but were low in fibre content (ranged from 2.20% to 2.33%). The anti-nutritional factor contents of the flours were found to be below toxic levels: oxalate ranged from 210 to 250 mg/100g flour, alkaloids ranged from 362 to 406mg/bOg flour, phenols ranged from 80 to 105 mg/bOg flour, phytate ranged from 580 to 640mg/bOg flour, hemagglutinin ranged from 26.40 to 44.13 Hu/g flour, and trypsin inhibitor ranged from 124.8 to 136.4 TIA/g flour. Apart from the emulsion capacity (ranging from 3.62 to 5.31 g.oil/g. flour), emulsion stability (ranging from 7% to 10% for 6h holding time), and foaming capacity/stability (hardly measurable and of fleeting existence) which were low, other functional properties (water absorption capacity, gelation, and wettability) and the physical properties (bulk density and viscosity) of the composite flours were found appropriate, for complementary food manufacture. The microorganisms identified in the complementary foods before and during storage were predominantly Lactobacil/us spp. The composite flours and the complementary foods prepared with these flours as base were stable in lidded metallic containers and screw-capped plastic containers during storage for 36 weeks under ambient conditions. Sensory evaluation showed that Panelists' degree of liking for each of the complementary foods (freshly- prepared or stored) was not significantly different from their degree of liking for NTJTREND (a reference baby food). The protein efficiency ratios (PERs) of the ra diets ranged from 2.25 to 2.51 and compared favourably with the PER (2.45) of th casein-based diet. The digestibility coefficients and the apparent protein digestibility's of the rat diets ranged from 87.30% to 90.00%, and 69.70% to 78.50%, respectively, and both indices are very high. The cocoyam-soybean-crayfish based complementary foods are considered nutritionally adequate, organoleptically acceptable, easy-to-prepare, and shelf-stable when packaged in lidded metallic containers or screw-capped plastic containers and stored at 26.5 ± 0.3 °C and 70.8 ± 4.5% relative humidity.