Andrew Strak (abstrak@accesswave.ca)
Sun, 23 Jan 2000 20:54:48 -0400
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
----- Original Message -----
From: howgate <phowgate@rsc.co.uk>
To: <abstrak@accesswave.ca>; 'Seafood List' <seafood@ucdavis.edu>
Sent: Sunday, January 23, 2000 5:36 PM
Subject: Re: Haddock Flesh Discolouration
> Andrew
>
> On 21 January you showed two pictures of haddock, one discoloured. I
assume
> you were referring to the bright yellow fillet.
>
> Carotenoids can be taken up from the diet of animals and can colour the
> flesh. A common example, in the USA at least, is the yellow colour of
> corn-fed chickens. I assume this is due to the carotenoid, zeaxanthin,
that
> imparts the yellow colour to corn. Nearer to home, the pink colour of
> salmon, in the wild, is due predominately to the carotenoid astaxanthin,
> and other carotenoids in minor amounts, from crustacea in the diet. I can
> only write from experience of haddock landed in Britain. I have come
> across light pink colouration in haddock, and in cod, which is assumed to
> come from crustacea in the diet, but I have not come across the yellow
> colour shown in your picture. A number of carotenoids other than the pink
> astaxanthin and canthaxanthin are found in marine animals. Polychaete
worms
> are sources of a variety of carotenoids and, as I recollect, are described
> in: Simpson K.L. Katayama T. Chichester C.O., 1981, Carotenoids in fish
> feeds. In: Carotenoids as Colorants and Vitamin A Precursors, J.C.
> Bauernfeind, ed., Academic press, New York, pp 463-534. I write
'recollect'
> because I do not have a copy of this chapter, but I consulted the book in
> one of the academic libraries in Aberdeen and I no longer live in that
> city). Chemical analysis - not too difficult - will be able to identify if
> the colour is a carotenoid, and its nature.
>
> Let me put forward as a hypothesis that the haddock in question have been
> feeding on polychaete worms that contain a yellow carotenoid. If you know
> the catching ground of the haddock, you might be able to confirm from a
> marine laboratory if polychaete worms are likely to be an item of the
> haddock diet. Unless they had been feeding on corn!
>
> Given the known free-radical scavenging properties of carotenoids, and the
> benefits to health of carotenoids in the diet, the yellow colour should
> perhaps be seen as a benefit, not a defect.
>
> Peter Howgate
>
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