Investigation of Heat-induced Chemical Changes in Black-eyed Beans (Phaseolus vulgaris) with and without Dichlorvos (Sniper) Treatment Using Gas Chromatography-mass Spectrometry (GC-MS)

Aim: This research is to investigate the effect of heat on the chemical profile of black-eyed beans (Phaseolus vulgaris) treated under different conditions. Sample A (used as received from the farmer without further treatment) served as a control to compare with Samples B and C, which were treated with Dichlorvos (Sniper) using Gas Chromatography-Mass Spectrometry (GC-MS).

Study Design: This study prepared three black-eyed bean samples: untreated (Sample A), Dichlorvos-treated with black water discarded (Sample B), and Dichlorvos-treated without black water discarded (Sample C). Each sample was air-dried, washed, and cooked. Hexane extracts were analyzed using GC-MS to investigate the effect of heat on the chemical profile of the samples and the risks associated with the consumption of Dichlorvos (Sniper)-treated beans.

Place and Duration of Study: The study was conducted at University of Africa, Toru-Orua, Nigeria, from February to August, 2024.

Methods: Three black-eyed bean samples were prepared for analysis. Sample A (Untreated): 1000 g of raw beans were air-dried for 14 days, washed twice with 100 ml distilled water and cooked to dryness at 100°C for 60 minutes. The samples were air-dried again, pulverized, and stored for analysis. Sample B (Dichlorvos-treated, black water discarded): 1000 g of raw beans were treated with 5 ml Dichlorvos (Sniper), shaken gently for even distribution, air-dried for 14 days, washed twice with 100 ml distilled water, parboiled for 10 minutes and the black water discarded. The samples were cooked to dryness at 100°C for 50 minutes, air-dried, pulverized, and stored for analysis. Sample C (Dichlorvos-Treated): 1000 g of raw beans were treated with 5 ml Dichlorvos, agitated and air-dried for 14 days. The samples were washed twice with 100 ml distilled water and cooked to dryness at 100 °C for 60 minutes. The samples were air-dried, pulverized, and stored for analysis.

Results: GC-MS analysis identified 43, 51, and 31 compounds in Samples A, B, and C, respectively. Natural compounds included Prenol, Benzaldehyde, 2-methyl, Benzeneacetaldehyde, and o-Cymene, which contribute to beans' metabolism, aroma, and defense. Sample A (untreated) contained harmful contaminants such as 2-Propenoic acid, 2-propenyl ester (92.6%), a skin and respiratory irritant; 1,3-Butadiene, 2-fluoro (97.0%), a carcinogen; Benzene (81.9%), a known carcinogen; and Toluene (80.5%), which poses neurological and respiratory risks. Sample B (Dichlorvos-treated, black water discarded) had contaminants like Isobutane (92.9%), an asphyxiant; Cycloheptane (76.8%), which affects the central nervous system; and Benzaldehyde, 2-methyl (70.5%), a skin irritant. Sample C (Dichlorvos-treated, black water retained) showed lower contaminant levels, indicating reduced absorption or degradation of certain toxic chemicals during processing. The detection of harmful chemicals in Sample A highlights potential contamination from pesticides, poor agricultural practices, or environmental pollutants. The persistence of toxic chemicals in all samples suggests that heat treatment causes thermal decomposition of pesticides into stable, harmful byproducts, which are absorbed into the bean matrix.

These findings emphasize the health risks associated with pesticide residues and the need for stringent monitoring, regulation, and control at every stage of bean production, handling, and storage.