OBIEWA, JAMES ODUOR (2016-05-23)

Nutrient analysis of vegetables plays a crucial role in assessing their nutritional significance. Plant foods provide almost all essential nutrients for human diet. Many stakeholders in human nutrition have emphasized the need for cheap and quality food alternatives. Information on nutrition is used more often by agencies in food production and public health like Food and Agriculture Organization (FAO) to promote consumption of the food products. People are looking for variety in their diets and are aware of the health benefits of fresh vegetables and are keen in food sources rich in antioxidant vitamins (vitamins A, C and E), Ca, Mg, K and fibre. These nutrient requirements can be realized through improved consumption of fresh vegetables. This study aimed at assessing the nutritional and mineral composition of various selected indigenous vegetables, which are commonly consumed in Kendu Bay, Homa Bay County. Consumption of foods that meet nutritional requirements is essential for good health. There is risk of people suffering from malnutrition and related diseases if the nutritional status of the foods they consume is not known. A total of 48 samples of each vegetable variety; Solanum nigrum, Cleome gynandra, Justicia flava, Amaranthus hybridus, Vigna unguiculata and Crotalaria brevidens together with corresponding soil samples where the vegetables grow were collected from various parts around Kendu Bay and analysed for nutrient contents. Samples were collected from selected plants during flowering stage for purposes of botanical identification. The samples were manually washed with distilled water and residual moisture evaporated at room temperature. Samples were oven dried in paper envelope at 55◦C for 24 hours, ground into fine powder using pestle and mortar and sieved through 20-mesh sieve. The sieved samples were weighed and 2.0 g subjected to wet ashing and analysed for K, Mg, Ca, Fe, and Mn. Minerals were extracted from the soil using 10.0 g of the sample and 20 ml of aqua regia. Fresh vegetable samples were macerated for provitamin A and vitamin C analyses. Moisture was analyzed through oven drying. Minerals Mg, Ca, Fe and Mn were analyzed using atomic absorption spectrometry (AAS) while K was analyzed using both AAS and flame photometer. The vitamins; Beta carotene and vitamin C were analyzed using UV-spectrophotometry and titrimetric methods, respectively. The beta carotene contents of the vegetables were used to estimate retinol equivalent. Moisture and ash contents of these vegetable species were determined using Association Official of Analytical Chemists (AOAC) methods. Validity of the instruments was tested by regression, Horwitz ratio and standard recovery method. The results obtained were ash 9.71-19.83 mg / 100 g, moisture 77-87%, all the vegetables had vitamin C contents above recommended daily allowance (RDA) of 40-70 mg , Vigna unguiculata gave 64.9-80.8 mg / 100 g vitamin C (wet weight), β-carotene contents were in the range 3.34-9.40 mg / 100 g. Mineral contents varied among species with K 309 mg / 100 g in Amaranthus hybridus, Mg 17-24 mg / 100 g, Ca 90-149 mg / 100 g, Mn 5.78-22 mg / 100 g, and Fe 41-77 mg / 100 g. There was a positive correlation between soil and vegetable mineral contents with Vigna unguiculata giving a strong positive correlation coefficient (r = 0.952) while Crotalaria brevidens gave a weak correlation of 0.26645. The Ca contents were below detectable limits in some of the samples. The findings of the study will provide additional information on the nutritional status of the selected vegetables in Kendu Bay and will be of great interest to the consumers, farmers, the Ministry of Public health and nutritionists in the provision of public awareness.



thesis april 2015.pdf

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