Paul, back to the basics then!
There are 144 BTU's latent heat of fusion in a pound of ice. The sensible
heat of water is 1 BTU per pound. So one pound of ice will lower 144 pounds
of water by one degree F (or, of course, one pound of water by 144 degrees
F - that's how I used to cool swimming pools in Oman).
Fish is not 100% water and the sensible heat of the solids is only about .2
BTU's per pound - but if you assume the fish is 100% water then the
calculation should be simply to divide 144 by the temperature reduction you
want to achieve. The assumption that fish is 100% water will give the
calculation an excess of ice of about 20 to 30% depending the fat (moisture)
content of the fish. So, to cool fish from 62 degrees F to 32 degrees F
("delta T" of 30 F) the calculation is simply 144/30 = 4.8 pounds of fish
per pound of ice. You can of course make the same calculation in the metric
system.
And you are right. The term saltwater ice is misleading. The ice formed by
freezing seawater or brine is 100% pure water with a melting point of 32
degrees F. Its melting point is depressed only because it is mixed with
salty water (that's what you call "flow ice" isn't it?). As you know, one
means of making pure ice is to freeze seawater and then harvest ("skim" or
centrifuge) the ice from the salty water/ice mixture.
By the way, the old 1973 "Salt Brines" pub is now online at:
<http://seagrant.orst.edu/sgpubs/onlinepubs/h99002.pdf>. It needs the free
Adobe Acrobat Reader to download.
Ken H.
Kenneth S. Hilderbrand Jr.
Seafood Processing Specialist
Sea Grant Extension Program
Oregon State Univ. Marine Science Center
2030 Sth Marine Science Drive
Newport, Oregon 97365-5296 USA
phone: 541 867-0242
fax: 541 867-0138
email: <ken.hilderbrand@hmsc.orst.edu>
-----Original Message-----
From: owner-seafood@ucdavis.edu [mailto:owner-seafood@ucdavis.edu]On
Behalf Of Andrew Strak
Sent: Sunday, July 23, 2000 6:36 AM
To: PDIONPDA@aol.com; seafood@ucdavis.edu
Cc: Hector.Lupin@fao.org; jperalta@iloilo.net; SHRIMPKEM@aol.com;
tplabuza@tc.umn.edu
Subject: Re: Amount of Ice to Chill Fish
Hi Paul,
Following is the original message/request that started the thread. I do not
think that our intention was a full blown review of the subject by any means
although we may have deviated here and there from the main course. Our
dissent if there was truly any has centered around the praticality of some
thermodynamic calculations in those situations of uncontrollable or
difficult to determine heat leaks into the system and other variables.
Certainly, we can expand the subject but what is specifically of your
interest than?
Best regards,
Andrew Strak
From: André & Joline Belliveau (bellcom@klis.com)
Date: Thu Jul 13 2000 - 21:50:24 PDT
There must be an easy was to determine how much ice should be added to a
known quantity fish to chill it to a determined temperature knowing how much
fish one has and what the temperature is before adding ice. Anybody out
there know what it is and is willing to share it?
----- Original Message -----
From: <PDIONPDA@aol.com>
To: <seafood@ucdavis.edu>
Cc: <abstrak@accesswave.ca>; <Hector.Lupin@fao.org>; <jperalta@iloilo.net>;
<SHRIMPKEM@aol.com>; <tplabuza@tc.umn.edu>
Sent: Saturday, July 22, 2000 3:51 PM
Subject: Re: Amount of Ice to Chill Fish
> To all who are interested in the benefits of good icing procedures,
>
> We all know that the post harvest handling of fish is greatly influenced
by
> basic icing procedures and techniques. The post mortem changes that occur
> shortly after death are greatly influenced by temperature. How quickly are
> the fish iced after landing and how quickly they are reduced to 0C to -1C.
In
> some species, especially the hakes of the world are, rapid chilling rates
> have direct influence on the quality (and value) of the raw material
landed
> at dockside. For all those who are into salmon, rapid chilling at
slaughter
> also has a great influence on the quality of the fresh fillet.
>
> I am surprised that the discussion of the forms of the icing medium has
not
> come up in the recent discussion such as, crystal ice, flake ice, slush
ice,
> ice made with sea water (I was told once that there was no such thing as
> saltwater ice), ice mixed with seawater, salt mixed with ice, flow ice
> (binary ice) and RSW. Even though 0C is 0C, ice is not necessarily ice.
>
> We haven't even started to touch on boxes, bins, tubs and containers yet.
>
> Paul Dion
> Paul Dion Associates, Inc.
> Plymouth, MA
> USA
>
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