Richard
A plot of the amount of water frozen out against temperature is shown in:
Johnston, W.A., Nicholson, F.J., Roger, A. & Stroud, G.D., 1994, Freezing
and refrigerated storage in fisheries. FAO Fisheries Technical Paper 340,
FAO, Rome, Italy, ISBN 92-5-103579-2, page 5. Reading off this figure gives
75% of the water frozen out at -5ºC and 88% at -20ºC. The relationship to
quality loss is through temperature - the lower the temperature, the lower
the rate of deterioration, and the smaller the proportion of water not
frozen. An excursion of temperature during processing up to -5ºC will not
have a significant effect on quality providing the excursion occurs over a
short time, a couple of hours or so. What is more damaging to quality is
that the fish has apparently been stored at -20ºC before processing and will
be stored at -18ºC afterwards. These temperatures are too high for
maintenance of good quality in frozen fish; a better temperature for storage
would be around -30ºC.
Peter Howgate
----- Original Message -----
From: "Richard Chivers" <richardchivers@btconnect.com>
To: "seafood" <seafood@ucdavis.edu>
Sent: Monday, January 06, 2003 9:26 AM
Subject: Ice content in frozen fish
> Does anyone have any references for the ice content of frozen fish and its
> relationship to the quality of the end product e.g. drip loss, toughening
> etc.
>
> The context is a client who buys in frozen fish in shatterpacks, cuts into
> portions, glazes, repacks as IQF and distributes. During this process the
> temperatures of the fish rises from -20(C to -5(C, then back to -18(C. I
> wish to advise them on the quality losses with some reference points.
>
> Thanks in advance.
>
> Richard Chivers
>
>
>
This archive was generated by hypermail 2b29 : Thu Jan 09 2003 - 04:13:28 PST