Your problem is probably not rigor but toughening due to the evolution of
formaldehyde in frozen storage. Twice freezing accelerates the problem
because
the TMAOase enzyme is membrane bound and freezing releases the
activity. I can
send you several papers on the problem but it is particuarly serious in frozen
gaddoids. This problem is likely to produce excessive drip loss on thawing,
toughening as observed in the cooked product, and excessive water loss on
cooking. You will often also see blow off of batter or coatings if
deep fried.
The solution?
Store fish at < -30 degrees celsius and do not double freeze unless absolutely
necessary
Good luck!
T.Quoting Steve_Lamming@youngsbluecrest.com:
> 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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