This explanation is on target, plus there could be possible negative influences due to product dehydration. Proper use of phosphates could help protect moisture content during frozen storage and thawing, and cooking. The dominate component in the cod is water. The product water or moisture is the natural lubricant to minimize tough texture, plus it carries the essential flavors and nutrients.
From: owner-seafood@ucdavis.edu [mailto:owner-seafood@ucdavis.edu] On Behalf Of Andrew Strak
Sent: Thursday, May 03, 2007 12:12 PM
To: Steve_Lamming@youngsbluecrest.com; seafood@ucdavis.edu
Subject: RE: Rigor mortis
It is probably formaldehyde, as Tom G. stated in the earlier follow-up. Apparently at freezing TMAO undergoes the following chemical change: TMAO à 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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