Investigation of the Effectiveness of Sodium Chloride (NaCl) Washing in Preserving Proximate and Phytochemical Quality of Dichlorvos-Adulterated Black-Eyed Beans (Vigna unguiculata)

Abstract

Pesticides support agricultural productivity and food security, but excessive use leads to harmful residues on food, posing serious health risks—especially from organophosphates, which affect the nervous system. Vulnerable populations are most at risk, and staple crops like legumes often contain unsafe residue levels due to repeated pesticide application. This study evaluated the effects of dichlorvos adulteration and sodium chloride washing on the pH, proximate composition, and phytochemical profile of black-eyed beans. Three samples were analyzed: Sample A (control), Sample B (dichlorvos-adulterated and cooked), and Sample C (dichlorvos-adulterated, NaCl-washed, and cooked). Sample A exhibited near-neutral pH, while Sample B showed increased acidity due to pesticide degradation. Sample C demonstrated partial pH normalization, indicating reduced residual acidity. Proximate analysis showed that Sample A retained high nutritional quality, with protein (20.91%), fat (17.43%), carbohydrate (51.87%), fiber (2.83%), and ash (4.32%). In contrast, Sample B recorded reduced protein (14.32%), fat (15.46%), ash (3.54%) and carbohydrate (22.31%) and slightly lower fiber (2.38%), reflecting nutrient degradation. Although Sample C showed improvement in moisture, ash and fibre levels toward Sample B values, significant reductions persisted. GC-MS analysis revealed that Sample A contained major beneficial compounds such as Methyl 4-O-methylpentopyranoside (51.84%), cis,cis,cis-7,10,13-Hexadecatrienal (22.32%), and Methyl isohexadecanoate (16.56%). Sample B showed reduced natural phytochemicals and the presence of toxic contaminants including ethylene sulphide (14.82%) and Bis(2-sulfanylethyl) ethylboronate (12.51%). Sample C exhibited partial recovery, with beneficial compounds such as Pentaacetyl-α-D-galactosamine (21.15%) and Methyl isohexadecanoate (11.13%), alongside reduced contaminants like β-chlordene (0.57%). Overall, dichlorvos compromised food quality, while salt washing provided partial remediation.