Processing of Yam Paste (Amala): A Product of Fermented Yam (Dioscorea rotundata) Flour

Abstract

This study was designed to evaluate the processing of yam paste (amala): A product of fermented yam (Discorea rotundata) flour. The sliced yam samples were fermented for 72 hours. The microorganisms were isolated and identified. The pH, TTA, temperature, proximate, anti-nutrient, mineral composition and sensory analyses of the sample were determined. The microbial loads increased with fermentation time. The isolates identified were Pseudomonas aureginosa, Staphylococcus aureus, Bacillus subtilis, Lactobacillus plantarum, Lactococcus lactis, Aspergillus niger, Saccharomyces cerevisiae, Fusarium oxysporium, and Candida tropicalis. pH decreased from 6.4 to 4.9 while TTA and temperature increased from 0.16 to 4.24% and 28oC to 34oC. The crude protein (2.46%) and moisture contents (12.32%) increased in the fermented sample with a decrease in ash (0.70%), fat (0.19%) and carbohydrate contents (80.76%). The saponin and phytate decreased from 31.29 to 11.45mg/g and 11.12 to 5.77mg/g. The fermented sample showed an overall acceptability. Improvement in the nutritional and reduction in antinutritional contents of the fermented sample suggests its usefulness as a food source for humans. The microorganisms associated with fermented yam tubers, processing of yam tubers into flour to produce amala and determining the nutritional and antinutrient content of both unfermented and fermented yam. The fermentation process improving the quality and nutrient content of the yam tubers suggested the method as more promising in producing food for humans.