Nutritional evaluation and validation of mondia whytei (hook F) skeels asclepiadaceae

Abstract

The nutritional evaluation of the root bark of Mondia whtyei (Hook.F.) Skeels Asc1epiadaceae was carried out for vitamins, minerals, proteins, and carbohydrates. This was done for the old plant root samples collected from different localities namely: Buyangu, Elimas, Hamisi, Malava, and Naitiri. Young plant root samples were collected from Malava only. The mean ~-carotene content (~g/g of dry matter) was 4.4 - 21.8 for full-grown samples. The young sample had higher concentrations of 10.1 ~g/g compared to the 8.0~g/g for the full-grown sample. The mean ~-carotene content varied with respect to localities. The water-soluble vitamins composition analyzed by high performance liquid chromatography (~g/g dry matter) were: niacin (5.3 - 81.6), riboflavin (6.5 - 24.5) and thiamine (7.8 - 37.0) for full-grown samples. The Malava young sample mean niacin, riboflavin and thiamine contents (~g/g dry matter) were 73.5, 18.5, and 40.1 respectively. The concentration of water-soluble vitamins niacin, riboflavin and thiamine was higher in young than old M whytei roots from Malava. There was also considerable variation for full-grown sample and hence ecological influence on concentration of the water-soluble vitamins. The minerals were determined using atomic absorption spectrophotometry, AAS, for calcium, iron, copper, manganese, magnesium, zinc, cadmium and lead, whereas flame emission spectrophotometry, FES was used for the determination of sodium and potassium. The mean mineral content (mg/g of dry matter) ranges were: Na (5.61 - 24.13), K (11.34 - 32.05), Ca (3.09 - 8.26), Mg (1.40 - 2.93), Fe (0.21 - 0.44), Zn (0.04 - 0.07), Mn (0.04 - 0.05), Cu (0.00(3) - 0.01), Cd (0.05 - 0.09), and Pb (0.03 - 0.06) for the fullgrown samples collected from different localities. While for the Malava young sample the mean mineral content (mg/g of dry matter) were: 2.25, 5.54, 2.65, 3.77, 0.84, 0.07, 0.11,0.01,0.05, and 0.06 for Na, K, Ca, Mg, Fe, Zn, Mn, Cu, Cd, and Pb respectively. There was no general trend for the elements in the old M whytei roots in relation to the young plants. The full-grown root sample from different localities showed significant differences in mineral concentrations. The mean total protein content determined using the combustion method and the mean percentage range was (4.7 - 13.3) for full-grown samples. The young plant from Malava coritained 15.4 % oftotal protein while the mature plant from the same locality contained 6.9 %. The carbohydrates fructose, glucose, sucrose, and xylose were analyzed by high performance liquid chromatography (HPLC). The mean sugar content (mg/g dry matter) ranges were: fructose (7.9 - 15.3), glucose (4.0 - 9.0), sucrose (14.1 - 46.9), and xylose (9.2 - 12.8) for the full-grown samples. The mean content of fructose, glucose, sucrose and xylose (mg/g dry matter) were 42.3, 12.7, 132.2 and 51.8 respectively for the young Malava sample. The young Malava plant had higher sugar content than the old Malava plant. The concentration for glucose for full-grown samples also varied considerably. The sample collected from the young plant had high concentrations of the soluble sugars sucrose, xylose, fructose, and for glucose the concentration was also significantly different. The samples from Malava predominantly gave the highest concentrations of the sugars compared to samples from other localities except, for sucrose, which was highest for Elima's sample. The result obtained in this study for vitamins, minerals, proteins and carbohydrates indicated that the plant was rich in nutrients and can be used as a food supplement. The results also indicated variation with respect to locality and age of harvest.