Article

In Nigeria, and specifically in Taraba State, legumes such as cowpeas, groundnuts, and soybeans form a crucial part of the local diet and agricultural economy. Their high protein content, fiber, essential vitamins, and minerals make them an indispensable part of nutrition, especially in populations that rely heavily on plant-based diets. While the nutritional contributions of leguminous grains are widely recognised, concerns persist regarding their contamination with aflatoxins—naturally occurring mycotoxins produced by certain species of Aspergillus, particularly A. flavus and A. parasiticus. This study was conducted to determine the proximate composition, amino acid content and aflatoxin levels of selected leguminous grains retailed in Wukari, Taraba State. A total of 36 samples of various agricultural commodities, including shelled groundnut, soy beans, sesame seed, shelled melon, were procured from grain vendors operating in the markets of Wukari metropolis. These markets are namely Wukari New Market, Wukari Old Market and Dorowa Market which has distance of above 40km from Wukari city. The collection of samples took place during the period spanning from April to May of the year 2023. The sample size was determined using the composite sampling technique. Experimental procedures for proximate composition were carried out using the standard methods of Association of Official Analytical Chemistry, amino acid analysis was carried out using acid hydrolysis on grain samples employing the amino acid analyser while aflatoxin levels in samples were determined using the Enzyme-linked immunosorbent assay (ELISA) method. The results of proximate composition of legumes ranged from 3.62-9.12% ash content, 4.25-13.45% crude fibre, 18.06-42.22% crude protein, 30.51-57.11% ether extract, 5.13-10.44% nitrogen free extract and 4.53-11.10 moisture. The amino acid results of legumes ranged from 1.59-2.54% histidine, 2.58-4.72% isoleucine, 2.87-7.6% leucine, 2.08-6.2% lysine, 0.77-1.70% methionine, 2.81-5.71% phenylalanine, 1.13-3.73% threonine, 0.01-1.51% tryptophan, 2.82-4.79% valine, 5.85-8.87% arginine, 0.5%-16.04% aspartic acid, 2.3%-8.42% Serine, 11.87%-17.54% glutamic acid, 1.63%-6.49% proline, 2.14%-12.96% glycine, 3.10%-9.64% alanine, 1.26%-5.01% cysteine and 2.21%-7.33% tyrosine. There were significant differences (p<0.05) in the crude protein and moisture content of the samples among the three markets for shelled groundnut. There were no significant differences in the histidine and isoleucine residues of the essential amino acids of sesame seeds, but there was a recorded significant difference in the proline and glycine residues of the non-essential amino acids of the soya bean samples. There were no significant differences in the aflatoxin levels of shelled melon seeds, while there was a significant difference in shelled groundnut and soybean samples purchased from all the markets. Aflatoxin levels in legumes retailed in Wukari, Taraba State ranged from 0.57-1.17µg/kg in shelled groundnut samples, 0.47-2.27µg/kg in shelled melon samples, 1.53-3.17µg/kg in sesame seed samples, 0.10-0.20µg/kg in soybean samples, and 3.11-13.10µg/kg in These aflatoxin levels were within the permissible limits for total aflatoxins recommended by FDA and NAFDAC for all products intended for food, hence these legumes analysed in this study are safe for human consumption. The findings revealed that the proximate and amino acid composition were present at appreciable levels in the samples analysed.