Mineral Content of Some Plant Foods Grown in Nigeria: A Review

Abstract

Minerals are natural inorganic substances that possess definite chemical composition and atomic structure. Nearly five percent of the body is composed of inorganic materials, the minerals. Minerals do not serve as a source of energy for the body but have specific chemical functions. For this purpose, mineral content of some plant foods found in Nigeria were critically reviewed. The plant foods were classified into legumes (Vigna unguiculata, Cucurbitaceae, vigna subterranean, Arachis hypogeal, Glycine max, Phaseolus coccineus, Cajanus cajan, Kerstingiella geocarpa, Phaseolus vulgaris L., Phaseolus lunatus and Prosopis Africana); cereals (Zea mays, Sorghum bicolor, Pennisetum typhoides and Oryza sativa); roots and tubers (Dioscorea spp, Manihot esculanta, Xanthosoma sagititolium and Ipomoea batatas L.); fruits/vegetables/nuts (Musa spp, Psidium guajava, Carica papaya, Citrus sinensis, Ananus comosus, Malaudo mistica, Anarcardium occidentale, Veronia amygdalina L. and Dacryodes edulis). Atomic absorption spectrophotometric (AAS) method is used for the minerals determination except sodium and potassium which are usually determined using flame photometry while phosphorus is by using colorimetry. The mineral contents were found to be at the range of concentrations as Ca: 0.003 – 700.00, Mg: 0.0546 – 1420.10, Na: 0.0065 – 220.00, K: 0.010 – 817.40, P: 0.0130 – 5500.00 and Fe: 0.0067 – 36.00 mg/100g for legumes; Ca: 0.13 – 8490.00, Mg: 0.006 – 4571.00, Na: 0.019 – 375.69, K: 0.63 – 39856.00, P: 3.54 – 695.50 and Fe: 0.0005 – 1304.00 mg/100g for  fruits/vegetables/nuts; Ca: 1.05 – 290.00, Mg: 0.49 – 415.07, Na: 0.18 – 1365.05, K: 0.50 – 4276.04, P: 0.28 – 120.00 and Fe: 0.53 – 81.85 mg/100g for roots and tubers and Ca: 0.005 – 532.00, Mg: 1.54 – 348.30, Na: 0.006 – 520.00, K: 0.011 – 618.00, P: 73.00 – 46.30 mg/100g for cereals. Microelement concentrations of the foods varied appreciably. Zinc content was highest in Vigna unguiculata, Psidium guajava, Manihot esculanta and Zea mays with values of 162.00, 2209.00, 340.00 and 16.70 mg/100g, respectively. Legumes and fruits/vegetables/nuts are seen to be better sources of mineral than foods in the category of roots, tubers and cereals.

Keywords: Legumes, cereals, fruits, vegetables, snuts, roots, tubers, minerals.