4 research outputs found
Relation between TMAOase activity and content of formaldehyde in fillet minces and bellyflap minces from gadoid fishes
Minced fish is a significant component of a number of frozen fishery products like fish fingers, cakes and patties. Predominately minced fish is produced from gadoid species (Alaska pollack, cod, saithe, hake and others) possessing the enzyme trimethylamine oxide demethylase (TMAOase, E.C. 4.1.2.32) (Rehbein and Schreiber 1984). TMAOase catalyses the degradation of trimethylamine oxide (TMAO) to formaldehyde (FA) and dimethylamine (DMA), preferentially during frozen storage of products (Hultin 1992). In most gadoid species light muscle contains only low
activity of TMAOase, the activity of red muscle and bellyflaps being somewhat higher. In contrast, the TMAOase
activity in blood, kidney and other tissues, residues of which may contaminate minced fish flesh, may be higher for
several orders of magnitude (Rehbein and Schreiber 1984)
A sensitive trimethylamine-N-oxide aldolase assay in two steps without deproteinisation
4 páginas, 4 figurasA two-step assay for trimethylamine-N-oxide aldolase (the target enzyme) is described in which the second step, the indicator reaction, is of the enzymatic end-point type. This indicator reaction is carried out at a slightly alkaline pH, outside the target enzyme's active pH range. An effective inactivation of the target enzyme is thus obtained solely by shifting the pH to that of the indicator reaction, thereby avoiding a deproteinisation step. By inserting a downward pH step as the stopping method, many samples may be collected and applied to the indicator reaction simultaneously. These features make the method very productive and easy to performThis work was supported by grant AIR 3 CT 94-1921
from the European Community.Peer reviewe
Localization of formaldehyde production during frozen storage of European hake ( Merluccius merluccius )
5 páginas, 3 tablas, 2 figurasThe formation of dimethylamine and formaldehyde
from trimethylamine N-oxide by the enzyme
trimethylamine N-oxide demethylase in whole hake during
frozen storage was studied. The objective was to
check if there were parts of the muscle with a higher production
of dimethylamine and formaldehyde, and if the
presence of kidney during frozen storage had any significant
influence on the production. Three variables were
examined through one year storage. The first was anatomical
location, considering the red muscle and three
zones of white muscle, one located right over the kidneys,
the dorsal part over the viscera, and the tail. The
second variable was the temperature of storage, –11 °C
or –18 °C. Finally, the influence of kidneys during storage,
comparing fish with and without kidneys, was also
evaluated.
No differences were found in dimethylamine and
formaldehyde production between fish with and without
kidneys stored at –18 °C. However at –11 °C the
amounts of dimethylamine and formaldehyde detected in
fish without kidneys were, in some cases, higher than in
those with kidneys. Kidney removal does not have a statistically
significant influence on DMA and FA production
in frozen storage hake. Differences in dimethylamine
and formaldehyde values among different anatomical
locations were found, especially in those stored over
one year. It was found that, in general, the white muscle
located right over the kidneys produced more dimethylamine
than other parts of the fish.The authors wish to thank the European Commission for financial support of the Research
Projects FAIR-CT95-1111 and AIR 3-CT94-1921.Peer reviewe