Elemental characterization of Brazilian canned tuna fish using particle induced X-ray emission (PIXE)

The elemental composition of Brazilian canned tuna fish packed in oil and brine was determined using the particle induced X-ray emission (PIXE) technique. Three different brands representative of the Brazilian market were evaluated. The metallic cans were analyzed as well. The results indicate that the canned tuna is homogeneous (average variability ∼5%) inside the cans as far as elemental concentration is concerned. The data analysis reveals that the major elements present in tuna fish are Na, Cl, K, P and S with average concentration ranging from 800 to 2400 mg/kg, while Fe (14.22 mg/kg) and Zn (4.51 mg/kg) constitute trace elements. Significant variations in the elemental concentration of canned tuna across the brands were observed for most of the elements. For instance, significant higher concentrations of Mg, P, K and Zn were observed for brand P when compared to the other brands. Moreover, significant differences were observed between oil-packed and brine-packed tuna. In this case, higher elemental concentrations were obtained for oil-packed tuna. An increasing pattern in the concentration of Fe as a function of storage time was observed for two of the brands studied in this work. Finally, the results concerning the metallic cans identified two different types of cans, namely Fe-rich cans and Al-rich cans. In general, the results obtained in this work are in good agreement with previous measurements of canned tuna.