Effect of High-Pressure Processing and Frozen Storage Prior to Canning on the Content of Essential and Toxic Elements in Mackerel

The mineral content of canned (115 °C, 45 min; Fo = 7 min) Atlantic Chub mackerel (Scomber colias) previously subjected to different high-pressure processing (HPP) (200, 400, and 600 MPa for 2 min) conditions and frozen storage times (3, 10, and 15 months at −18 °C) was studied. Prior processing steps modified extensively the contents of essential and toxic elements, so that substantial changes were produced in canned fish. Thus, canned mackerel showed higher levels of most essential (Na, Ca, Fe, Co, Cu, Se) and toxic (Sn, As) elements when compared with initial raw fish; contrary, some essential (K, Mg, P) and toxic (Pb) elements revealed lower values in canned samples. HPP led to increased levels of essential (S, Se) and toxic (Cd) elements; the opposite effect was produced on Ca and Mn (essentials) and Ba (toxic) elements. Scarce effects of frozen storage time could be concluded; remarkably, storage time increase led to increased Ca and Mn levels, while produced decreases of K, Cd, and Pb contents. Changes in essential and toxic element contents are explained on the basis of protein denaturation, protein and lipid breakdown, water and liquor losses from the fish muscle, and muscle interaction with brine-packaging medium.