Analysis of Essential Minerals in Residues of Mangifera. Indica L. Grown in Selected Divisions of Mbeere South, Embu County, Kenya
Njiru, Michael Kariuki
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The mesocarp (edible part) of Mangifera. indica L. (mango) is known for its contribution towards addressing nutritional challenges that face most of the developing countries. Based on the Recommended Daily Allowance (RDA) recommended levels by National Research Council (NRC) USA, mangoes would provide sufficient amounts of essential minerals, sodium (Na), potassium (K), magnesium (Mg), calcium (Ca), Zinc (Zn), copper (Cu), iron (Fe) and manganese (Mn). However, as a result of consuming mangoes, over 150,000 tonnes of the residues (non edible parts) namely the epicarp (peels), endocarp (shell) and the seed kernels that account for 40-50 % of the fruit are dumped thus posing a concern on environmental pollution. A knowledge gap on the potential nutritional contribution and benefits of these residues in the arm of reducing environmental pollution is therefore called for. The Mbeere south in Embu county Kenya, grows varieties of mangoes some of which are ngowe, apple and van dyke. Residues of these varieties of mangoes grown in Mbeere were investigated to assess their food value particularly with regard to mineral content (Na, K, Mg, Ca, Zn, Cu, Fe, Mn). Mangoes were sampled twice randomly during the harvest period and the minerals measured using Atomic Absorption and Emission Spectrometry. Data analysis by one-way ANOVA was done using SPSS 18 for windows. The range of concentration (mg/100g) of essential minerals from lowest to the highest levels were as follows: In seeds; 0.48±0.05 (Cu, in apple) - 1492.05±43.75 (Ca, in ngowe): In endocarp; 0.38±0.02 (Cu, in ngowe) - 1689.5±9.15 (Ca, in van dyke): In peels; 0.38±0.03 (Cu, in ngowe) - 1482±2.05 (Ca, in apple). In most cases, there were no significant differences (p<0.05) in the levels of essential minerals both, between the residues and mango varieties. The seeds and peels residues as well as the ngowe and van dyke mango varieties recorded significantly higher levels of most minerals. Similarly, the levels of essential minerals decreased in the order Ca>K>Mg>Na>Fe>Mn>Zn>Cu. With regard to the RDA recommended levels of minerals, these findings indicate that mango residues are a rich source of essential minerals. This potential can be explored for other benefits such as for use in animal feeds/supplements than to cause the present hazard of environmental pollution. It’s a way of waste management.