This study was carried out to evaluate the absorption and distribution of heavy metals in three common Nigerian Vigna unguiculata beans and their end product (“moinmoin”). Three varieties of beans samples were processed into “moinmoin” and analysed for their heavy metals content using different packaging materials. The three varieties included drum, oloyin, and white beans popularly eaten in Yoruba land in Nigeria. Levels of iron, zinc, copper and chromium were determined in these samples using atomic absorption spectrophotometer of model 210 VGP. The packaging materials used were leaves, nylon, plastic and milk tin. The highest content of iron in “moinmoin” sample was obtained in “moinmoin” prepared from drum beans using nylon and plastic materials (16.8±1.09 mg/kg). The highest level of copper was obtained in “moinmoin” prepared from drum beans using milk tin (1.30±0.01 mg/kg). Concentration of zinc was found to be highest in “moinmoin” sample prepared from drum beans using plastic (24.3±0.05 mg/kg). No chromium was however detected in all the samples analysed for the research work including the leaves as a packaging material and the raw beans. Statistical analysis revealed a significant difference in metals in “moinmoin” using different packaging materials especially with copper and zinc at p< 0.05. A positive correlation was observed between iron and zinc at p< 0.01 (r =0.543) and between zinc and copper at p<0.05 (r=0.351). Inter-element association was high only for copper in nylon/zinc in plastic (r = 0.97) and iron in plastic/zinc in plastic (0.97). Metal levels correlated positively between beans and packaging materials, with coefficients ranging between - 0.50 for copper and 0.99 for iron.
Beans, Correlation, Heavy metals, Moinmoin, Packaging materials
