Trimethylamine spoilage

Another chemical method for measuring freshness, that is more rapid, continuous, and less destructive than other methods is the detection of volatile trimethylamine (TMA), dimethylamine (DMA), monomethylamine (MMA), and ammonia 14,15). Trimethylamine oxide (TMAO) is a decomposition product of proteins as well as present in excretions of fish 16). Spoilage bacteria can reduce TMAO to TMA plus small amounts of DMA, MMA, and ammonia. Tissue TMA levels have be correlated with the pungent odor associated with spoiled seafood as well as total bacterial counts 14). Researchers incorporated a test strip... 

FIGURE 18.4 Mobility spectra showing the formation of volatile amines from the spoilage of pork, turkey, beef, and chicken during storage at room temperature for 1 day. Calibration was with 2 ng of TMA (trimethylamine). TMA and cadaverine (CAD) are apparent in the mobility spectrum for each muscle food. The reagent gas was n-nonylamine. (From Karpas et al.. Determination of volatile biogenic amines in muscle food products by ion mobility spectrometry, AmZ. Chim. Acta 2002, 463(2) 155-163. With permission.)... 

The chemical spoilage indicators of total volatile base nitrogen (TVB-N) and trimethylamine (TMA) first became evident in the chilled samples on storage days 9-13 and not until on day 15 for superchilled pre rigor muscle (both salted and non salted). It could therefore be seen that superchilling had a positive effect on the slowing down the spoilage of the fish. 

The fishy OF is primarily due to the generation of Irimethylamine via bacterial action [130,131]. Trimethylamine is formed from trimethylamine oxide, which is a natural constituent of fish muscle. This reduction is accomplished through bacterial enzymes and involves a coupled oxidation of lactic acid to acetic acid and CO2 [ 132], The latter stages of fish spoilage involve the production of various nitrogen- and sulfin-containing compounds. These componnds prodnce pntrid, sulfury notes in the fish. 

Stansby, M.E., Speculations on fishy odors and flavors. Food TechnoL, 16, p. 28,1962. Watson, D.W., Studies on fish spoilage the bacterial reduction of trimethylamine oxide, J. Fish Res. Bd. (Canada), 4, p. 252, 1939. 

Trimethylamine has been used as an indicator of general fish spoilage, mainly in gadoids. It is useful as a rapid means of objective measurement in the mid- to late phases of spoilage but cannot be used as a freshness indicator, because the main source of TMA is bacterial growth (products), so levels are almost constant during the first days of iced... 

Other work on the topic of the spoilage of food, particularly fish quality and freshness, the volatile compound trimethylamine (TMA) is used as a marker. In fact, the odour of fish and the relevant chemicals is shown in Fig. 16.8. Traditionally headspace analysis is utilised and as pointed out by Nilsen et al. while such instruments with a high degree of automation are available for the trapping and... 

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