Assessment of Microbial Changes and Nutritional Qualities of Extruded White Yam (<i>Dioscorea rotundata</i>) and Bambara Groundnut (<i>Vigna subterranean</i>) Blends

Abstract

Two flavoured extruded products were developed by co-extruding yam grits (750 μm) obtained from white yam (Dioscorea rotundata) and bambara groundnut flour (250 μm) in 160:40 respectively obtained from white bambara groundnut with added flavouring agents of salt (1% - 3%) and sugar (4% - 6%) in the feed blends at screw speed of 70 rpm, 17.5%, feed moisture and at the barrel temperature of 145℃. The extruded products were packaged in low density polyethylene bag (0.02 μm gauge size) and stored at room temperature (28℃ ± 2℃) and at refrigeration temperature (9℃ ± 2℃) for a period of twenty weeks. The microbiological changes in the extruded products as determined by the total plate under both storage conditions showed that maximum total plate counts were 0.5 × 104 and 5.4 × 104 cfu/g at 9℃ ± 2℃ and 28℃ ± 2℃ respectively. Nutritional evaluation studies of extrudates were comparable (p ≥ 0.05) with standard casein diet with minimum crude protein content of 13.51% providing 1707.2 KJ energy per 100gof diet and supported weight gain and growth of laboratory animals.