Influence of lipids on dimethylamine formation in model systems of hake (Merluccius merluccius) kidney during frozen storage
1997
Joly, A. | Huidobro, A. | Tejada, M.
The role of non-oxidized and oxidized lipids in fish muscle proteins during frozen storage is a matter of controversy: some studies have shown that they have a detrimental effect, whereas others have shown a protective effect through a reduction in the amount of formaldehyde (FA) and dimethylamine (DMA) formed from trimethylamine N-oxide (TMAO) during frozen storage. A model system based on an extract of hake kidney as a source of trimethylamine N-oxide demethylase (TMAO-ase)and the substrate TMAO was prepared to study the effects of nonoxidized lipids and oxidized lipids with increasing peroxide values (POV) and of a cryoprotectant (glycerol) on TMAO-ase activity during frozen storage, using response surface methodology (RSM). At low POV, the oxidized lipids increased DMA formation, but at oxidation levels equal to or higher than 500 meq /kg they reduced the amount of DMA produced. This behaviour corroborates the hypothesis that oxidizing /reducing conditions strongly influence the capacity of the enzyme to catalyse the reaction. However, non-oxidized lipids were found to have a very weak inhibitory effect. Glycerol had a significant inhibitory effect on DMA formation, greater than that of oxidized lipids in the present enzymatic system.
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