Nutritional Evaluation of the Seeds of Corchorus olitorius: A Neglected and Underutilized Species in Nigeria

Abstract

Background and Objective: The seeds of Corchorus olitorius (C. olitorius), a neglected leafy vegetable in Nigeria, are usually discarded in the process of harvesting the leaves. This practice may result from a lack of knowledge regarding the nutritional content of the seeds as well as a lack of research interest. The aim of this study was therefore to evaluate the nutritional composition of the seeds of 14 accessions of C. olitorius. The results will help to determine the suitability of these seeds as a source of nutritious food for human consumption and of feed for the livestock industry. Material(s) and Method(s): The seeds of the 14 accessions of C. olitorius were procured from the seed bank of the National Centre for Genetic Resources and Biotechnology, Moor Plantation, Ibadan, Nigeria. Standard food composition analysis techniques were employed to evaluate the proximate, mineral and vitamin contents of the seeds. The obtained data were analysed with Genstat and SPSS. Result(s): The proximate components were present in varying ranges, as follows: moisture (6.087- 10.77 mg/100 g), ash (1.866-2.657%), fat (5.274-5.896%), protein (0.966-1.135%), fibre (0.973-1.913%) and carbohydrate (59.91-87.34%). The mineral contents were as follows: calcium (1.242-2.610%), iron (1.235-1.623 mg/100 g), potassium (0.320-1.232%), sodium (0.002- 0.007%), lead (0.150-0.274 mg/100 g), tin (0.086-0.167 mg/100 g), zinc (0.090-0.942 microg/100 g), manganese (0.123-0.147%), magnesium (0.896-1.475 mg/100 g), copper (0.126-0.143 mg/100 g) and phosphorus (0.624-0.973 mg/100 g). The vitamin contents included the following: 2.155-2.838 mg/100 g of vitamin A, 0.519-0.884 mg/100 g of vitamin C and 0.357-0.394 mg/100 g of vitamin D. The Na/K ratio ranged from 0.005-0.016 and the Ca/P ratio ranged from 1.31-3.43. The highest positive correlation coefficient (-0.05) was obtained between vitamin A and vitamin C (r2 = 0.521, 52%) and the highest negative correlation was observed between tin and manganese (r2 = 0.581, 58%). Principal component analysis revealed that two principal components with eigenvalues S1 accounted for 90.09% of the total variability among the accessions. These two components were carbohydrates (57.12%) and the moisture composition (32.37%). Conclusion(s): Seeds of C. olitorius are nutritionally adequate and have acceptable limits of metal contents. Thus, they have the potential to be incorporated into the human diet and livestock feed.Copyright © 2019 C.C. Isuosuo et al.