Andrew Strak (abstrak@accesswave.ca)
Tue, 25 Jan 2000 20:31:32 -0400
Peter,
The paper is attached for your review and the interest of others as well.
The colour intensity changes in frozen storage may reflect some shifts
within the isomeric forms of the pigment.
Andrew
----- Original Message -----
From: howgate <phowgate@rsc.co.uk>
To: <abstrak@accesswave.ca>; 'Seafood List' <seafood@ucdavis.edu>
Sent: Tuesday, January 25, 2000 5:04 PM
Subject: Re: Haddock Flesh Discolouration
> Dear Andrew
>
> Thank you for drawing my attention to the paper by Dyer on orange-red
> colour in haddock. I must get a copy as the published literature on
> discolourations in fish is very sparse. It is interesting to see that Dyer
> identified zeaxanthin in the fish. Chemistry textbooks give zeaxanthin as
a
> typical carotenoid and being responsible for the yellow colour of corn,
but
> that does not mean it is found only in corn. You are quite right to point
> out to Verhoeven, that the yellow colour is a quality defect, though
> probably, if it is a carotenoid, harmless, maybe even positively good for
> you. Health food stores sell zeaxanthin. Consumers look at yellow
> discolouration in chickens as a plus quality attribute, but I think you
> would have a hard job persuading consumers that the same type of
> colouration in haddock is a plus point. I doubt if algae would be the
> source of the pigment. As far as I am aware, haddock, certainly of the
size
> you are referring to, are carnivores and would not browse on
phytoplankton.
>
> I can't explain the apparent increase in intensity of colour during frozen
> storage. The perceived pink colour of salmon, particularly when pigmented
> with canthaxanthin, is reported to decrease in intensity during frozen
> storage, even though the amount of pigment as determined analytically does
> not change. Carotenoids will oxidise during frozen storage, but I do not
> know enough (anything) of the chemistry of carotenoids to predict if the
> oxidised product will be more or less intense that the parent compound.
>
> Peter Howgate
>
> ----------
> > From: Andrew Strak <abstrak@accesswave.ca>
> > To: phowgate@rsc.co.uk; 'Seafood List' <seafood@ucdavis.edu>
> > Subject: Re: Haddock Flesh Discolouration
> > Date: 24 January 2000 00:54
> >
> > Peter,
> >
> > Thank you for your insight. The fish was from the Barents Sea (unknown
> exact
> > location, though). In the meantime I have come across one old paper by
> E.G.
> > Bligh and W.J.
> > Dyer 'Orange-red Flesh in Cod and Haddock" - J.Fish.Res.Bd. Canada,
> 16(4),
> > 1959 not probably listed in any database anymore. Astaxanthin and
> zeaxanthin
> > in the proportion of 2:1 were found to be responsible for the
> pigmentation
> > of the flesh of Cod. Zeaxanthin was the only pigment detected in the
> flesh
> > of a similarly pigmented haddock. Therefore concerning the carotenoid
> > identification you are probably right on the point. What strange is that
> the
> > colour intensity seems to be increasing with the time in frozen storage.
> And
> > the incidence of the number of fish affected by the phenomenum in this
> case
> > is also pretty high (5%), unlike your experience or reported by Blight
> and
> > Dyer. Apparently there must some cargo ship carrying corn went down
> recently
> > :-).
> >
> > Andrew Strak
> >
>
>
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