Nutritional value, anti-nutrient and amino acid profile of raw and processed wild aerial yam (Dioscorea bulbifera) meal

Abstract

The study evaluated the effect of different processing methods (boiling, toasting and soaking) on the nutrient and of wild aerial yam (Dioscorea bulbifera). One kilogram of raw wild Dioscorea bulbifera (RWDB) was boiled for 30 minutes at 100?C, another one kg was soaked for 24 hours. Toasting of another one kg of Dioscorea bulbifera tubers were carried out for 30 minutes. The raw and processed tubers were dried, milled and chemically analysed for proximate compositions, phytochemical components, minerals and amino acid content. Mean dry matter, crude protein, lipid, fibre, ash and carbohyd-rate contents of boiled wild Dioscorea bulbifera meal were 10.86%, 89.14%, 11.63%, 32.28%, 4.10%, 3.61% and 66.53% respectively. There were significant differences (p<0.05) in all parameters for all the processing methods. RWDB meals was a good source of Calcium (0.27%), Phosphorus (0.38%), Magnesium (0.29%), Potassium (0.75%), Sodium (0.25%), Iron (56.78%), Copper (9.91%), Zinc (52.87%), Manganese (17.51%) and Cobalt (0.52%). Increase in contents of macro and micro minerals were observed during toasting and these were significantly (p<0.05) superior to raw and other processing methods. Values obtained for soaked WDB meal were significantly lower (p<0.05) in all the phytochemical substances (tannin 0.0012, oxalate 1940, flavonoid 0.002) determined, while boiled WDB meal had the least HCN. Boiling process improved the amino acid profile of WDB meal, and there were significant differences (p<0.05) in all its parameters. Boiling compared to other methods appeared to be the best in terms of nutrient content, anti-nutritional factors and amino acid profile, therefore stands as the preferred method for preparing WDB as a livestock feed ingredient