Avaliação da frescura e contaminação por metais pesados em camarões de superfície comercializados nos mercados da Cidade de Maputo

Abstract

The present study aimed to evaluate the freshness and heavy metal contamination of surface-dwelling shrimp sold in markets in the city of Maputo. Freshness was assessed through sensory analysis—evaluating texture, color, and odor—while moisture and ash content were determined via oven-drying and muffle-furnace calcination, respectively. The quantification of heavy metals (As, Cd, Cu, Cr, Co, Pb, Fe, Ni, Se, Sr, and Zn) in the shrimp shells and muscle tissue was performed following acid digestion on a hot plate, with analysis conducted using ICP-OES. The freshness assessment indicated that the shrimp were sold in good condition and were acceptable for consumption. Moisture content was lower in the shells than in the muscle tissue, highlighting the need for frozen storage to extend shelf life. Ash content was higher in the shells compared to the muscle tissue. Concentrations of heavy metals such as Cd and Pb in all samples exceeded the limits established by EU regulations ([Cd] and [Pb] > 0.5 mg/kg, w/w), indicating contamination by these pollutants. For Cu, Cr, Co, Fe, Ni, Zn, Se, Sr, and As, further comparison against maximum tolerable daily intake levels (mg/day) is required to determine whether their presence poses a toxic risk. Among the markets studied, the Xipamanine Market exhibited the highest concentrations of heavy metals. These results demonstrate that, despite an acceptable level of freshness, the consumption of shrimp sold in the markets of Maputo city poses a potential public health risk.