Dear Mike:
Will reply in the text,
"Strang, Mike" wrote:
>
> Fellow listers,
>
> I seek expert advice on freezing fish, both raw and processed, multiple
> species.
>
> 1. What is the optimum freezer storage temperature?
>
In theory, the lower the freezing temperature, the better.
Practical storage temperature is at -18 to -20 C. This temp is normally
used commercially, after fish freezing.
This temp is also used to maintain frozen fish during transport; in
refrigerated vans and in refrigerated reefer van containers.
> 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?
>
Freezing temperature normally is from -50 to -45 C. Plate freezers and
blast
freezers, normally operate at this temperatures.
Some tuna catchers are freezing yellowfin tuna on board at -65 C.
--It would be best to remove all the sensible heat prior to freezing by immersing fish in ice water. When the internal fish temp have achieved 2 or 0 C, then that is the time to freeze.
Methods for cooling sensible heat should be separated and be different from methods for cooling latent heat. --
After the fish have cooled to 0 C, freeze it in a tunnel freezer at -45 C or lower. The thermal arrest(crystal formation) period should be done and completed within 2 hours.
If freezing is done this way, small crystals are formed. --
Freezing the fish in your suggested process may not be complete, and may end up with large water crystals. This will eventually lead to high thaw drip losses.
Freezing fish using storage temperature at -18 C is also not appropriate. --
> 4. What role does fat content play in freezing quality?
A lot, and fat is a critical factor. It ranges from rancidity development, product discoloration and etc. Fatty fish are suggested to be glazed prior to storage.
> > 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
I hope this helps.
Regards,
Jose --
----------------------- Jose P. Peralta, Ph. D. Food Engineer Inst. of Fish Processing Technology College of Fisheries, Univ of the Phil Visayas 5023 Miag-ao, Iloilo, Philippines Tel (63 33) 315 8289 FX (63 33) 315 8289, 315 8353 Cell (0917) 302 1282 EMail jperalta@iloilo.net -------------------------
My Web Page http://users.iloilo.net/jperalta/home43.html
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