Assessing metal contaminants in milled maize products available on the Ghanaian market with Atomic Absorption Spectrometry and Instrumental Neutron Activation Analyser techniques

Abstract

The study is undertaken as a quality assurance exercise, to investigate the quality of milling plates available on the market by evaluating the metals released from them into food products in contact with them during comminution. Two locally manufactured and one imported milling plates were used in both dry and wet milling of maize samples collected from different geographical locations in the country (N = 12). Atomic Absorption Spectrometry and Instrumental Neutron Activation Analyser techniques were used to detect and quantify the metals present as contaminant in the flour samples over a seven-week period. While Na, Fe, Zn, Mn, Mg, Ca and Al were detected, As, Cd, Cu, Co, Pb and Ni were either absent or below detection limits. The concentrations of the metals were observed to decline with continuous use of milling plates, with Mg recording the highest of concentrations in each week and Mn, the vice versa. The results showed that the quality of the milling plates contributed to the levels of metals seen in the samples. In terms of the extent of contamination, the imported plate was deemed best of the three milling plates used whiles the two locally manufactured plates were comparable. Wet milling process was touted as better than dry milling in contributing to metal contamination of milled food products. Also, the maize samples collected from different places were shown to exhibit varying metal concentrations. The sample from Ejura-Sekyere Dumase was showed to be more contaminated than from other sources. When the flours were used to produce consumable foods, porridge and kenkey, the metal concentrations in them were comparable. The outcomes of the study show that education on sources of food contamination should be organized for stakeholders in the maize cultivation and processing industry and regulatory systems should also be strengthened to safeguard consumers’ health.