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

Abstract

The mineral content of canned (115 ºC, 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 ºC) 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.

Effect of Previous Frozen Storage and Coating Medium on the Essential Macroelement and Trace Element Content of Canned Mackerel

“…Thus, liquor produced from fish tissue, especially during the needed thawing step, can lead to an important decrease in the mineral content. This element release ought to increase with protein damage and, accordingly, with time and temperature of frozen storage [ 13 , 23 ].…”

“…Recently, a previous 6-month frozen storage (−18 °C) led to a general decrease in essential element ( K , Mg , Ca , Mn , Fe , Se , P , and S ) content in brine-canned mackerel ( S. colias ) [ 34 ]. In a subsequent study, Prego et al [ 23 ] analysed the effect of the previous frozen storage time (–18 °C, up to 15 months) on the content of essential elements in the corresponding brine-canned mackerel ( S. colias ); as a result, an increased frozen storage time led to an increase in Ca and Mn contents but produced a decrease in K content.…”

“…After vacuum sealing, cans were subjected to the sterilisation process in a horizontal steam retort (115 °C, 45 min; F o = 7 min) (CIFP Coroso, Ribeira, A Coruña, Spain) [ 23 ]. After completing the heating time, steam was cut off, and the remaining steam was flushed away with air.…”