A Study on Heavy Metals Comparison in Processed Tomato Paste and Fresh Tomatoes Sold in a Market in Umuahia Metropolis of Abia State Nigeria
Author(s): Kelechi E Onwuka, Aghalibe U Christopher, Igwe JC, Achulonu C Victor
Heavy metals are among the largest contaminants of food products. Once metals are present in vegetables, their concentrations are rarely modified by industrial processing techniques, although in some cases washing may decrease the metal content. In this study, levels of heavy metals in tinned, sachets, tomato pastes and fresh tomatoes sold in markets in Umuahia, Nigeria were evaluated by Atomic Absorption Spectrophotometry. The result obtained for tinned tomatoes were: iron, 0.03 -2.78 μg/g; lead, 0.01-0.18 μg/g; chromium, 0.03-0.05 μg/g; copper, 0.01-0.04 μg/g; nickel, 0.03-0.1 μg/g; zinc, 0.06 0.11 μg/g; calcium, 0.04 -0.8 μg/g and cadmium, 0.00-0.01 μg/g. The mean values for sachet tomatoes were: iron, 0.38-0.84 μg/g; lead, 0.03-0.18 μg/g; chromium, 0.03-0.04 μg/g; copper, 0.02-0.04 μg/g; nickel, 0.03-0.08 μg/g; zinc, 0.049-0.14 μg/g; calcium, 0.4-1.02 μg/g, while cadmium was not detected. The mean concentration values in fresh tomatoes sold in markets and farm land were: iron, 0.025-0.075 μg/g; lead ranges between 0.03-0.19 μg/g; chromium, 0.00-0.27 μg/g; copper, 0.002-0.10 μg/g; nickel, 0.00-0.15 μg/g; zinc, 0.05-013 μg/g; calcium, 0.24-0.74 μg/g; while cadmium was not detected in all fresh and farm land samples. These values indicate that levels of investigated metals in the analyzed tomatoes were below the permissible levels of metals recommended as dietary intake in tomato.