Proximate and Mineral Elements Composition of the Tissue and Peel of Dioscorea bulbifera Tuber

Abstract

The proximate principles and mineral elements in the wet and dry tissue and peel of Dioscorea bulbifera were determined using standard methods. The proximate principles were analyzed using AOAC methods, the mineral elements namely calcium, magnesium, iron, zinc, copper, sodium and potassium by absorption and emission spectrophotometry and phosphorous by molybdovanadate method. All the parameters analyzed apart from carbohydrate and energy value showed tissue/peel ratios of less than 1.0 which was consistent with the observed significantly lower levels of the mineral elements and proximate principles in the tissue than the peel (p<0.01) excepting carbohydrate and energy value. Additionally, the about constant tissue/peel ratios observed for the mineral elements and some proximate principles such as ash, crude fibre, fat and protein for the wet and dry samples of Dioscorea bulbifera were indicative of the stability of these nutrients and in about the same proportions in the tissue and peel upon drying at 40^oC. The nutritional significance of the mineral elements in the tissue and peel of Dioscorea bulbifera was also highlighted in the discussion.