Effect of neutral and oxidized lipids on protein functionality in megrim ( Lepidorhombus whiffiagonis W.) and sardine ( Sardina pilchardus R.) during frozen storage

Abstract

The effect of added cod liver oil and oxidized cod liver oil on protein solubility, apparent viscosity and emulsifying capacity was measured during frozen storage (−18°C) of vacuum packed minced muscle of two non-dimethylamine (DMA)-forming species, megrim ( Lepidorhombus whiffiagonis W) and sardine ( Sardinia pilchardus R.). The aim was to establish the role of both unoxidized and oxidized lipids in protein functionality in the absence of interference due to the effect of formaldehyde on the proteins. The results showed that, with the addition of cod-liver oil (CLO), the three protein functional properties were equal to, or slightly lower than, the untreated controls in both species. Samples with oxidized cod-liver oil (OCLO) added showed lower protein solubility and viscosity, whereas the emulsifying capacity values were higher than in the controls. Hence, in non-DMA-producing fish species, no protective effect on fish protein can be attributed to neutral lipids.