Effect of freeze–thaw cycles on total and heme iron contents of bonito (Sarda sarda) and bluefish (Pomatomus saltator) fillets

The effects of the number of freeze–thaw cycles on total and heme iron contents of bonito (Sarda sarda) and bluefish (Pomatomus saltator) fillets were investigated. The prepared fillets were packaged in polyethylene bags, the bags were heat sealed and than these samples were subjected to a total of 5 freeze–thaw cycles. Effects of freeze–thaw cycles on total and heme iron content of bonito and bluefish fillets were statistically significant (P<0.05). The total and heme iron contents of both fishes decreased as the number of freeze–thaw cycles increased, and the highest losses were found after the second freeze–thaw cycle. Total and heme iron losses were higher in bluefish fillet. The multiple freeze–thaw process therefore is not suitable in terms of total and heme iron contents.