Both of them are highly volatile therefore lots of them will be purged in
frying, with some TMA being retained by the oil but they will be still
present in the fish after deep frying anyway. However, since the oil of deep
fried fish coats our taste buds and affects olfactory glands, both ammonia
and TMA are not so noticeable in this case as during eating any microwaved
or steamed product. For this reason microwaving or steaming methods are
commonly used in sensory evaluation to determine spoilage substances in the
fish if a raw state evaluation proves inconclusive.
Andrew Strak
----- Original Message -----
From: "Adam Simpson" <AdamS@ahsl.co.nz>
To: <AdamS@ahsl.co.nz>; <seafood@ucdavis.edu>
Sent: Thursday, May 18, 2000 6:06 PM
Subject: RE:
> Thanks all
>
> Just to clarify a point, would this ammonia or TMA smell still be apparent
> subsequent to deep frying?
>
> Adam Simpson
> Health Protection Officer
> Public Health
> Auckland Healthcare Services
>
>
> > -----Original Message-----
> > From: Andrew Strak [SMTP:abstrak@accesswave.ca]
> > Sent: Thursday, 18 May 2000 01:18
> > To: AdamS@ahsl.co.nz; seafood@ucdavis.edu
> > Subject: Re:
> >
> > Adam,
> >
> > Although ammonia is amongst the common products of fish spoilage, in
> > particular for shrimp and elasmobranchs, but for most of other sea
> > finfish
> > it is actually a compound called TMA or trimethylamine derived from the
> > reduction of TMAO or trimethylamnine oxide during fish decomposition.
And
> > if
> > the odor threshhold value for ammonia in fish is 110 ppm, for TMA is
only
> > 0.6 ppm, therefore it is most often the TMA level that determines if the
> > product is being considered spoiled or not. Apart from those two pretty
> > sharp smelling substances, there is also a gamut of others, some of them
> > being typical to specific species and others to the spoilage stages and
> > substrates involved. What all of them have in common, it is their
> > extremely
> > obnoxious sensory properties but not any risk of burning anybody's mouth
> > at
> > their predominant concentration levels.
> >
> > Regards,
> >
> > Andrew Strak
> >
> >
> > ----- Original Message -----
> > From: "Adam Simpson" <AdamS@ahsl.co.nz>
> > To: <seafood@ucdavis.edu>
> > Sent: Tuesday, May 16, 2000 11:24 PM
> >
> >
> > > Hi List
> > >
> > > I have received several complaints relating to a very strong ammonia
> > smell
> > > associated with fillets from various different types of fish. I
believe
> > > this is an indication of spoilage and have also been made aware it
> > relates
> > > to the gutting of the fish. Is there any literature or comments out
> > there
> > > to provide me with further explaination/clarification? Could this
smell
> > > ever reach the stage of causing a physical reaction such a burns to
the
> > > mouth?
> > >
> > > Much appreciated
> > >
> > > Adam Simpson
> > > Health Protection Officer
> > > Public Health, Auckland Healthcare Services
> > >
> > >
>
>
This archive was generated by hypermail 2b29 : Thu May 18 2000 - 16:02:27 PDT