Proximate And Selected Metals Analysis Of Yam (Dioscorea Alata) Commercialized In Local Markets Of Jimma City, Ethiopia

Abstract

In this study, nutritional, anti-nutritional, and mineral compositions of yam tubers (Dioscorea alata) commercialized in the local markets of Jimma City, Ethiopia were investigated. The study was on red and white yam varieties, which are commonly commercialized in the city. For each variety 1kg sample was separately collected in plastic bags. Their nutritional compositions such as moisture, crude protein, total ash, crude fiber, crude fat, total carbohydrates and gross energy were determined using the standard, Association of Official Analytical Chemists (AOAC) method. The obtained results for the red and white yam samples, respectively, were (59 and 60 mg/100g) moisture content; (2.42 and 6.12 mg/100 g) crude protein; (3.23 and 3.74 mg/100 g) total ash; (1.36 and 1.31 mg/100 g) crude fiber; (0.16 and 0.09 mg/100 g) crude fat; (33.83 and 28.74 mg/100 g) carbohydrate content; (146.44 and 140.25 mg/100 g) gross energy. The antinutritional components, i.e., oxalate and phytate components were determined by titrimetric method. The obtained values were 0.47 and 0.34mg/100 phytate and 1.80and 1.76 mg/100 g oxalate, respectively. Mineral compositions such as Ca, Mg, Fe and Zn were determined using a flame atomic absorption spectroscopy. The mineral contents of the yam samples were Fe (6.96 and 16.52 mg/100g), Ca (121.26 and 221.73 mg/100g), Mg (104.54 and 118.37 mg/100g) and Zn (44.44 and 56.30 mg/100g) in red and white yam samples, respectively. Student t-test (p<0.05) demonstrated that there was significant difference between the two yams (red and white) in the studied nutritional, anti-nutritional, and metal compositions.