ABSTRACT

Rasping, dewatering, fermentation, pulverization, sifting and thermal dehydration processes were used to produce a storable breakfast food from the peeled tubers of an edible landrace of trifoliate yam (Dioscorea dumeturum) whose identity was established clonally by fingerprinting the crop's genomic DNA in addition to morphological markers. The trifoliate yam product had a creamy-light brown colour and a packed bulk density of 0.46g/cm3. The water and oil absorption capacities were 40g/g and 1.71g/g respectively. Brabender amylograph reading with 15% suspension (in water) of the product gave a maximum gelatinization viscosity of 1,740 A.U. and gelatinization temperature of 85.6-91.8°C, as opposed to 1,150 A.U. (maximum viscosity) and 83.9-87.6°C (gelatinization temperature) of 15% suspension of starch from the trifoliate yam raw material. Cooking time of the product (in water) was 1.83 minutes. The breakfast food (from trifoliate yam) had a proxiniate composition of 5.05% moisture, 1.20% ash, 3.63% fibre, 11.12% protein, 0.68% ether extract, 78.32% carbohydrates and a caloric value of 1.52M 3/100g. The product had a zinc content of 0.58 mg/bOg, and was relatively high in potassium (2,75 mg/bOg). Vitamin C and vitamin A contents of the product were 18.56 mg/bOg and 108.97 p.g/lOOg respectively. Lactic acid bacteria were identified as the probable fermentation organisms during the fermentation process. Ten percent suspension of the product in distilled water had a pH of 4.2. The product, stored in sealed polyethylene bag, was found to be an unlikely source of botulism. Confirmatory product safety test with guinea pigs gave 0% mortality. Aggregate size analysis showed that all the product particles were <4mm and >0.063mm, with 76.4% of them being between 0.5mm and 2mm. Sensory evaluation of the brepkfast porridge, made with the particulate product, showed that the 30 semi-trained assessors liked the colour, taste, flavour and mouthfeel of the meal.