Andrew Strak (abstrak@accesswave.ca)
Wed, 9 Jun 1999 19:24:53 -0300
Dear Luis,
Yes, it is true that most of pioneering and very extensive work on the
mechanics of microbiological fish spoilage was conducted most than 5 decades
ago. But there are still some research centres specialized in that kind of
research one of them being the Danish Institute of Fishery Research at
http://www.dfu.min.dk/micro/ssp/ and Paw Dalgaard may be a good contact.
Concerning the ice issue and its quality, any freshly made ice would reflect
the microbiology of the water it was made of and to a degree of the handling
methods and contacts with any contaminated surfaces during blowing and
storage. But bacteria, and mostly spoilage causing psychrophilic flora can
and will grow in the ice easily, and in particular in the presence of
organic matter, such as glycoproteins coming from the slime, wash water
dripping and blood and the count could go as high as several hundred
thousands per gram after 10 days. Therefore, I will advise to use fresh ice
for a new trip and not to re-use any ice from the previous trip and in
particular the ice that was used for cooling your catch unless you do not
have any fresh ice around and there is a risk that you fish would get
excesively warmed-up. Please rememer that even unused ice in the fish hold
would still supports a significant bacteria growth without being in any
contact with fish and its count can be in the vicinity of 10,000-100,000 per
gram after 10 days.
There is no difference between various types of ice concerning their
enthalpy or heat content. However, any finer ice of a larger surface such as
flake ice will be cooling your catch faster but will also melt faster giving
some impresion that it is not so 'cold' as slow melting one due to a lower
surface/volume ratio for ice cubes. Please also remeber that almost 100% of
the cooling 'power' of the ice comes from its melting action where it
absorbs 80 cal/g still being at OC and that is equivalent to raising
temperature of 1 g of water from 0C to +80C. The specific heat of ice is a
relatively low though, and if you have some freshly made ice at -30C it will
need only 13 cal/g to be raised to the temperature OC.
Best regards,
Andrew Strak
-----Original Message-----
From: Luís Paulo Silva Pimentel <luispasp@usp.br>
To: seafood@ucdavis.edu <seafood@ucdavis.edu>
Date: Wednesday, June 09, 1999 11:29 AM
Subject: ice on fish boats
>Hi seafood listers,
>
>I am looking for some references about quality control of ice in fish
>boats, or else about microbiology of ice from fish boats. I found only
>few references about packaged ice, and fewer about ice to preserv fish
>quality.
>
>Thanks,
>
>Luís Paulo Silva Pimentel
>
>
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