Determination Of Selected Trace Elements And Beta-Carotene In Fresh And Dried Indigenous Vegetables As Potential Food Supplement From Kiambu, Kenya

ABSTRACT

Population growth, shortage of food due to unpredicted weather coupled with HIV/AIDS has increased nutritional deficiencies in people living in developing world. Use of micronutrients presents a low-cost strategy for achieving large reductions in death caused by malnutrition. The indigenous green leafy vegetables are of much importance among food crops as they provide adequate amounts of vitamins, immune boosting trace elements and anti-oxidants. The nutritional value of the indigenous vegetable remains underutilized due to their seasonal nature and lack of awareness. They are plenty during rainy season but most of it goes to waste during this period because there is no better method of preserving and processing them to stay longer for the dry season. This study was undertaken in 2012 in Lari and Limuru in Kiambu County to determine the levels of Zinc (Zn), Iron (Fe), Manganese (Mn) and Beta-carotene in fresh, solar-dried and open dried indigenous vegetables and to formulate a food supplement. Indigenous vegetables analyzed include Gynandropsis gnandra (spider plant), Corchorus olitorius (Jute), Cucurbita maxima (pumpkin leaves), Vigna unguiculata (kunde) and Symphytum offinale (mabaki). Beta-carotene was separated using open column chromatography (OCC) and quantified spectrophotometrically. Atomic absorption spectrophotometer (AAS) was used to determine Zn, Mn and Fe. Indigenous vegetables were dried for preservation using open drying and roof top solar drier. A vegetable mix powder was formulated from analyzed indigenous vegetables so as to meet the recommended dietary allowance of vitamin A, zinc, iron and manganese. Growth performance, feed efficiency and hematological parameters were determined by feeding mice with various proportion of the formulated vegetable mix powder added to basal diet. The mice were divided into four groups. One of the groups was fed with a basal diet which served as a control, while the other three were fed diet containing mixture of prepared basal diet (without inclusion of zinc, iron, vitamin A and manganese) with 25%, 50% and 75% of the formulated indigenous vegetable food supplement ad lib for 42 days. Beta-carotene levels in indigenous vegetable ranged from 9.61±0.36 mg/100 g to 0.24±0.01 mg/100 g dry weight with highest level being fresh Gynandropsis gnandra. Zn levels ranged from 1.62±0.54 mg/100 g to 0.24±0.09 mg/100 g with highest being fresh Cucurbita maxima. Mn levels ranged from 12.93±3.98 mg/100 g to 0.15±0.02 mg/100g with highest being fresh Symphytum offinale. Fe levels ranged from 90.78±31.34 mg/100 g to 2.45±0.35 mg/100 g with highest being fresh Gynandropsis gnandra. There was a significant reduction in the beta-carotene levels in both solar drying and open drying (p