TMAO aldolase in fish products. A key to reduction of the quality problems connected with formaldehyde and dimethylamine.

The formation of formaldehyde and dimethylamine are main factors in the reduction in quality of lean fish like cod during frozen storage. They are formed from trimethylamine-oxide, catalysed by the enzyme trimethylamine-oxide aldolase (TMAOase; EC 4.1.2.32) which is situated mainly in the inner organs like gall bladder, spleen and kidney. The presence of the enzyme in other marine species is not thoroughly described, and it is to be expected that TMAOase activity may be the cause of formaldehyde formation and quality deterioration in other products than those formed from lean fish.
Products of commercial importance to the Nordic fish industry vere screened for TMAOase activity.
TMAOase was almost only found in gadoide fishes. The TMAOase activity concentrations varried much between individuals. Results from the frozen storage experiment showed that the formation of formaldehyde at -10°C was both proportional to the TMAOase activity and the storage time. Therefore TMAOase activity concentration can be used as a selection criteria to sort out individuals less suitable to frozen storage.