Distribution of Metals in Red and White Axial Muscles of Three Fish Species from the Krasnoyarsk Reservoir

The content of metals in fish fillet is an important criterion for food safety and nutritional benefits. Fish fillet is composed of both white and red muscles, but the standard method only detects metal content in white muscle. The true metal content in fish fillet can be underestimated due to this approach. So far, metal content in different types of muscle tissue of freshwater fish remains virtually unstudied. The aim of the present research was to study the metal content in red and white muscles of roach Rutilus rutilus, bream Abramis brama and pike Esox lucius that live in the Krasnoyarsk reservoir. Twenty metals were measured in the dry mass of red and white muscles of three fish species using inductively coupled plasma (ICP-OES) spectrometry. The contents of macronutrients such as K, Ca and Mg were higher in white muscle fibers and Na – in red fibers. Of the 16 metals regarded as trace elements, the highest contents in the muscles were noted for Fe (20.5-177.8 μg/g), Zn (26.7-79.0 μg/g), and Al (15.2- 67.2 μg/g), regardless of the fish species and type of tissue. Li (0.01-0.09 μg/g) and Cd (0.01-0.03 μg/g) had the lowest concentrations. Among trace elements, the contents of Cu and Fe were significantly higher in the dry biomass of red muscle compared with white muscle for the three fish species. The content of Zn was higher in the red muscle of bream and pike. Almost all other trace elements also tended to accumulate in higher concentrations in the red muscle. Differences between red and white muscles in the contents of trace elements such as Pb and Sr were species-specific. The distribution of metals between the two types of muscle fibers demonstrated by the freshwater species examined in this study was similar to the distribution of metals in marine fish, except the distribution of Sr. Thus, the greater capacity of the red muscle for accumulating most heavy metals confirmed in the present study may indicate a greater risk to health in eating this type of tissue