Gas Chromatographic Determination of Dimethylamine and Trimethylamine in Seafoods

Abstract

The volatile amines dimethylamine (DMA) and trimethylamine (TMA) are common degradation products of TMA-oxide in marine fish- Both compounds are used as important indicators of quality in seafoods. DMA is produced along with an equimolar quantity of formaldehyde by action of an endogenous enzyme found primarily in gadoid fish. TMA is produced in fresh, but not frozen seafoods by a bacterial enzyme. The current AOAC method for determination of TMA in fish is based on the colorimetric estimation of TMA as a picrate salt. This method is not specific for TMA; ammonia, monomethylamine, and DMA also form corresponding picrate salts. Gas chromatography provides a means of separating and quantitating the individual volatile amines. A simple perchloric acid extract of fish is neutralized with potassium hydroxide and extracted with benzene. The amines are then separated by gas chromatography on a porous polymer packed column and detected by using a nitrogen-phosphorus-specific flame ionization detector. The method provides simple, rapid simultaneous quantitation of DMA and TMA, and is applicable to a wide variety of seafoods.

Feasibility Study on the Determination of Fish Freshness by Trimethylamine Headspace Analysis

“…After the layers separated 1 JLL aliquot of the toluene layer was injected into the GC. The procedure is basically that of Lundstrom and Racicot (1983). The most important modification was substitution of tolucne for the benzene used in the original procedure.…”

“…MOST SPECIES of marine fish and shellfish produce in their digestive process trimethylamine oxide (TMAO) which plays a role in osmoregulation. In frozen fish TMAO is reduced by endogenous enzymes to dimethylamine (DMA) and formaldehyde whereas in fresh or iced fish it is reduced by bacterial enzymes to trimethylamine (TMA) (Regenstein et al, 1982;Caste1 et al, 1971;Lundstrom and Racicot, 1983;Hebard et al, 1982). The concentration of the amines in fish tissue is both time and temperature dependent, and is therefore related to the deterioration of the fish.…”

“…Wong and Gill (1987) developed a procedure for the determination of TMA based on oxidation of TMA with phenazine methasulfate in the presence of TMA dehydrogenase. Ritskes (1975), Dunn et al (1976), Hiatt (1983), Lundstrom and Racicot (1983) and von Stockemer and Kruse (1985) determined trimethylamine in fish tissue by gas chromatography (GC).…”

Determination of Trimethylamine in Spinach, Cabbage, and Lettuce at Alkaline pH by Headspace Solid‐Phase Microextraction

“…Characteristic rotten fish odor is attributed to TMA, together with ammonia, indole, skatole, and hydrogen sulfide derived from deamination of fish protein. TMA can be used as an indicator of seafood freshness because the amount of TMA is closely related to the quality of seafood (Lundstrom and Racicot 1983). In addition to fish and seafood, TMA is found in various foodstuffs, which gives the undesirable rotten fish odor to some foods.…”

Effect of Frozen Storage Temperature on Free and Bound Formaldehyde Content of Cod (Gadus Morhua) Fillets

“…These two metabolites have been used as indicators of gadoid frozen storage deterioration. DMA is the frozen storage index of choice since it can be extracted quantitatively (Ruiter and Wesemen, 1976;Tokunaga et al 1977;Lundstrom and Racicot 1983) whereas HCHO can only be partially recovered from fish muscle tissue Poulter and Lawrie 1978;Radford and Dalsis 1982). Further clarification of formaldehyde's contribution to protein changes in fish muscle during frozen storage would clarify the toughening mechanism which may involve HCHO.…”