Nutritional evaluation and proximate analysis of varieties of some edible leafy vegetables in Northern Nigeria

Abstract

Vegetables are highly consumed in all the states across Northern Nigeria where they constitute a major source of nutritious food. However, their assessment as food, which is based on their chemical analysis, has not been adequately studied and documented in the areas. Standard procedures were used to determine the proximate and chemical composition of all vegetable species analysed. Atomic absorption and flame spectrophotometer test was used to determine the mineral composition. The results were compared using an analysis of variance test. There were significant differences in the nutritive values of the various vegetables (p>0.05) studied. Despite differences in the chemical composition of the vegetable species, the overall nutritional potential of the whole vegetable species was quite good. The results of the analysis showed high significant amounts of protein, and minerals, ranging from 1.24 to 48.44 mg/g and 0.09 to 57.54 mg/g for macro and micro elements respectively. Furthermore, crude fibre ranged between 3.32 to 19.76% and carbohydrate ranged from 20.54 to 64.78%, both of which were found to be relatively high. All species were moderate in fat content, with a range of 1.11 to 8.43%. Although, Pb and Cd were detected in some of the species of the vegetables. However, the results indicated that the studied vegetables can be suggested for human consumption.

Assessment of the Heavy Metals’ Levels, Phytochemical Profiles, Mineral and Proximate Compositions of Four Commonly Consumed Vegetables in Lagos State, Nigeria

“…Crude protein contents ranged between 7.80-10.91% in for vegetables. These percentages agreed with those reported by Oluwole et al [7] but were lower than those reported by Odoh et al [31] and Chatepa and Masamba [32] for some commonly consumed vegetables Africa. Thus, plant based proteins are reported to supply up to 12% body proteins [33].…”

“…However, carbohydrate contents in the four vegetables ranged from 67.51-77.63%. These values conform to the findings of Hussain et al [30] and Oluwole et al [7] but were above those documented by Odoh et al [31]. Carbohydrates are one of the essential energy sources in diet and as much as 60% may be provided [34].…”

“…Crude fibre contents recorded ranged from 8.94-9.86% in all the four vegetables studied. This value was close to those reported by Oluwole et al [7] but was below those documented by Odoh et al [31], Oluwole et al [5] and Chatepa and Masamba [32] for some African vegetables. Crude fibres havebeen documented to aid human wellbeing if consumed appropriately.…”

“…These percentages were close to those investigated by Hussainet al [30] and Oluwole et al [6,7]. But, Odoh et al [31], Oluwoleet al [5] and Chatepa and Masamba [32] had previously reported increase in the moisture contents for some vegetables in Nigeria and Malawi. These reductions in moisture have been attributed to increase in shelf life of the vegetables.…”

“…Crude fat contents of the four vegetables ranged from 0.21-0.99%. These valuesare close to the values documented for some Nigeria vegetables [7,34] but the values were lower than those investigated in earlier researches [30][31][32]. Vegetable fats are said to be rich in basic unsaturated fatty acids which are considered to be significant in human diet and health.…”