Evaluation of selected nutrients in mulberry (morus alba L) varieties grown at Kari station-Thika, Kiambu County
Sabina, Wambui Ngigi
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Mulberry is a multipurpose plant whose use is well documented and it is perhaps one of the very rare tree species that can serve many functions of mankind namely fodder, fiber, fuel and food since its leaves and fruits are highly palatable and nutritious. Leaves and fruits are known to be rich in proteins, vitamins, carbohydrates and carotene, minerals such as calcium, iron, potassium and zinc. Different parts of this plant; leaves, fruits, roots, stem and shoot bark are known to have medicinal properties such as reducing blood sugar, blood pressure and cholesterol and the fruit juice prevents premature aging and impotence. In Kenya mulberry has been used for silkworm rearing, as part of diet for cattle, and in poultry rations and other ruminants. Recently mulberry has found its use as a vegetable and food supplement but levels of micro and macronutrients in leaves and fruits of different varieties are not well documented in Kenya. Different mulberry varieties are grown at KARl station- Thika for the purpose of feeding silkworms and the leaves are now being processed into powder form for human consumption. This study therefore determined the levels of nutrients in leaves and fruits of eight (8) different mulberry varieties (lthanga, Thika, Embu, Limuru, S54, Kanva, Thailand and Ichinose). The leaves and fruit samples were collected and analyzed for potassium, calcium, zinc, iron, vitamins A (p-Carotene), C (Ascorbic acid) and E (a -tocopherol), carbohydrates and proteins. The Ca, Zn and Fe were analyzed using AAS, K using flame photometry, carbohydrates, PCarotene, a -tocopherol and proteins content were analyzed using UVNisible spectroscopy while ascorbic acid was analyzed by a titration method. The mean levels obtained in leaves and fruits ranged from 34.25±2.50 - 148.42±1.44 mg/l00g for Ca, 141.81±2.50 - 435.93±1.40 mg/lOOg for K, O.13±O.Ol - 0.43±O.010 mg/lOOg for Zn, O.55±O.01- 5.62±O.OOmgllOOg for Fe, 1.71±O.03 - 56.81±O.08 mg/lOOg for p-Carotene, 394.00±7.00 - 644.33±1.15 mg/l00g for ascorbic acid, 11.06±O.94 - 16.845±O.3G mg/l00g for a-tocopherol 87.12±6.92 - 426.36±9.1 mg/lOOg for carbohydrates and 1.24±O.34 - 49.55±O.29 mg/lOOg for proteins. Ichinose leaves recorded the highest levels of Ca and K, Thika leaves were significantly higher in zinc, Limuru leaves were higher in Fe, Kanva leaves were higher in carbohydrates, S54 leaves were significantly higher in vitamins A and E, Ithanga leaves were significantly higher in ascorbic acid and Thailand leaves were significantly higher in proteins. Embu fruits recorded significantly higher levels in Ca and K, Limuru fruits were highest in Zn, Thika fruits were higher in Fe and S54 fruits were higher in carbohydrates. The results showed that all varieties had substantial amount of the nutrients but in varying proportion and there were variations in levels of nutrients in the leaves and fruits of the same mulberry variety with levels being higher in leaves than in fruits of most varieties. Among all the nutrients studied, 13- carotene and ascorbic acid levels in fresh mulberry leaves of all the varieties and also carbohydrate levels in Kanva variety were found to be higher than the RDA. However Kanva and Embu varieties were higher in most macronutrients while Thika and Limuru were higher in most micronutrients Therefore all the varieties can be used to provide cheaper and locally available source of nutrients. The results of the present study will be availed to relevant authorities and also to sensitize the public.