It is probably formaldehyde, as Tom G. stated in the earlier follow-up.
Apparently at freezing TMAO undergoes the following chemical change:
TMAO --> DMA + FA. But the enzymes appear instrumental for this
reaction to take place since there are some species quite high in TMAO
but without that FA build-up and resultant toughening. The problem may
be further exacerbated if there are reducing conditions in the flesh
resulting in oxygen depletion (vacuum packing or ascorbates). Those
reducing conditions may be also created by the nucleotide reactions and
this may bring this association to the rigor mortis states.
Andrew
________________________________
From: owner-seafood@ucdavis.edu [mailto:owner-seafood@ucdavis.edu] On
Behalf Of Steve_Lamming@youngsbluecrest.com
Sent: Wednesday, May 02, 2007 5:38 AM
To: seafood@ucdavis.edu
Subject: Rigor mortis
Dear all,
I am experiencing a real textural problem (toughness) in Pacific Cod
which is more pronounced in fish <2kg, and is even more pronounced in
twice frozen products produced from such fish.
However, fillets sold in chilled form appear to be consistently good
quality, regardless of the size or age of the H&G fish from which they
originate (up to 1 year old H&G that is).
My out take from this is that obviously the larger the fish the longer
it will take to go through rigor, and with twice frozen product,
processed quickly, the muscle may still not have gone through rigor
before refreezing.
On the other hand, fillets sold in chilled form will be defrosted for at
least 24 hours before retail sale, in which case rigor is likely to have
passed, hence the satisfactory texture.
Does any have a view on the time/temperature relationship required for
completion of rigor in fish such as Pacific Cod?
Is there any analytical technique for determining pre-rigor, rigor,
post-rigor condition?
Thanks in anticipation of your help on this one.
Best regards,
Steve
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