Dear Mike
Short answers to your queries are:
1. What is the optimum freezer storage temperature?
As low as possible. In practice, fishery products can be maintained in very
good condition for 12 months when stored at/below -30ºC. Temperature
of -18ºC referred to in many regulations is not low enough for storage
beyond about 2/3 months.
2. Is it better to rapidly bring internal temperatures down to optimum
storage temperature?
Better than what? Products should be frozen in equipment designed to bring
the temperature down rapidly, typically within 4 hours of start of freezing
to a product mean temperature of -30ºC.
3. Or, can you get away with removing most of the latent heat from the
product in a freeze tunnel, and let the fish finish off in storage?
No!
4. What role does fat content play in freezing quality?
Fat oxidises during frozen storage resulting in off flavours. Fatty fish
should be stored at/below -30º and wrapped or glazed to protect the product
from oxidation.
You should consult textbooks on fish technology for amplification of these
brief replies. A source of advice is the site www.onefish.org. Look at the
product utilization section for Torry Advisory Notes (TANs) on
freezing/frozen storage. Try nos. 27, 28, 34, 35, 57, 62, & 75. An excellent
account of good freezing and cold storage practices is: 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. In the USA, FAO publications can be obtained in the USA
from Bernan Associates, (www.bernan.com), 4611-F Assembly Drive, Lanham, MD
20706-4391, Toll Free: 1-800-274-4447. Additionally, academic institutes
associated with the Sea Grant Program often issue advisory material about
freezing and frozen storage of fish.
Peter Howgate
----- Original Message -----
From: Strang, Mike <Mike.Strang@us.fjord.com>
To: HACCP mailing list (E-mail) <seafood@ucdavis.edu>
Sent: Tuesday, June 12, 2001 2:05 PM
Subject: Freezing
> Fellow listers,
>
> I seek expert advice on freezing fish, both raw and processed, multiple
> species.
>
>
> 1. What is the optimum freezer storage temperature?
>
> 2. Is it better to rapidly bring internal temperatures down to
> optimum storage temperature?
>
> 3. Or, can you get away with removing most of the latent heat
> from the product in a freeze tunnel, and let the fish finish off in
> storage?
>
> 4. What role does fat content play in freezing quality?
>
> Any and all information would be appreciated.
>
> Thanks!
>
> Mike Strang
> Quality Control Manager
> Ducktrap River Fish Farm, LLC
> 57 Little River Drive
> Belfast, Maine 04915
> Mike.Strang@us.fjord.com
> Phone: 207 338-6280
> Fax: 207 338-6288
>
>
>
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