>From my experience, high salt content is a concern for tuna canners because it correlates closely with poor quality as a consequence of slow freezing. If the brine freezing is rapid then the outside of the tuna is quickly frozen and becomes a barrier for further salt penetration into the flesh. Slow freezing allows a longer time for salt to migrate from the brine freezing solution into the flesh and the quality of the tuna may have deteriorated significantly before the fish are completely frozen (bacterial and autolytic spoilage.) Hope this is useful.
Klaus Schallié
Aquaculture & Molluscan Shellfish Specialist
Canadian Food Inspection Agency
Burnaby, B. C.
Telephone (604) 666-4427 ext. 277
Facsimile (604) 666-4440
e-mail schalliek@inspection.gc.ca
>>> "P Howgate" <phowgate@rsc.co.uk> 12/07 /01/11:38 am >>>
Dear Jon
Tunas frozen at sea are typically held in refrigerated seawater for a few
days until the hold is full, then frozen in concentrated brine. The tuna
will absorb salt, the ultimate concentration in the flesh being obviously
dependent on the time in the seawater/brine, and the size of the fish. This
salt content is of little concern to tuna canners unless it is very high
because oftten enough tuna is caned in brine, but salt contents in incoming
material are usually measured in tuna canning plants so that the salt
contents of packing brines can be adjusted to give the required content.
There is an excellent account of the treatment of tunas on seiners, and
information on salt uptake, in Burns, F.D., 1985, Tuna handling and
refrigeration on purse seiners, NOAA Technical Memorandum NMFS-SWR-011.
Salt content is most accurately and precisely measured by digestion and
titration, but there is a paper strip method - Quantabs - and salt meters
based on conductivity of an aquaeous extract are vailable. Check with a
laboratory suppliers for details.
Peter Howgate
US Dept. of Commerce, NOAA, NMFS
----- Original Message -----
From: Pamela Tom <pdtom@ucdavis.edu>
To: Seafood HACCP Mailing List <seafood@ucdavis.edu>
Sent: Thursday, December 06, 2001 5:15 AM
Subject: Inquiry - salt content in tuna
Dear listers,
I am trying to find information about salt (NaCl) content in tuna. I know
that the absortion of salt occurs when improperly freezing tuna in brine
but I'd like to know the process, the reason for this absortion, etc. I am
also looking for rapid salt content detection systems in tuna. Most
methods consist on titration. Is there any other rapid reliable method not
based in titration? What about legislation? I don't find any for salt
content in tuna products.
Thank you much,
Jon Egana
IKERTEK Diagnostics, S.L.
Notario Etxagibel, 8-1º
20500 ARRASATE
Spain
ikertek@terra.es
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