howgate (phowgate@rsc.co.uk)
Sun, 13 Jun 1999 15:10:47 +0100
Dear colleagues
At the end of May there was some discussion about CCP's for fish at landing
sites. In one of these messages, in response to a recommendation for
sensory assessment being used to monitor fish, I wrote:
'Spoiled fish which would be rejected on Ben's criteria would most likely
be safe, though unpleasant,
to eat because pathogenic bacteria would die in competition with the
spoilage flora.'
An observant reader wrote directly to me taking me to task for this
statement and asking for references. Usually I am careful not to make an
assertion without their being supportable by references. I slipped up on
this occasion, but the topic raises some points of interest that might be
worth discussing in this group.
I made the statement because I have heard microbiologist colleagues of
mine, from more than one institute, make the statement in formal and
informal meeting and gatherings. I would accept that the assertion I made
is too general to true in all cases. If I had thought twice about I should
have realised that. I am well aware of studies on prepacked fish that show
the growth of pathogens like Listeria and Clostridium spp. in spoiling fish
under these conditions at least. The original query in May related to
unpackaged, chilled fish and I had that in mind when I replied. I would
welcome comments on some points.
Would the original assertion be true of fish stored in ice? The loading of
pathogenic bacteria would be that originating naturally, and not
necessarily the rather high loadings of spiked samples used in laboratory
studies.
The fish would be stored in ice which would be favourable to psychrophilic
spoilers and not human pathogens (Listeria excepted). This may be conducive
to at least to inhibition of growth of pathogens, if not reduction in
numbers. Studies on prepackaged fish are often carried out at abuse
temperatures.
Anyone have any information on this topic? My microbiologist colleague
thought that there should be some literature on the subject, but probably
dating from early work on microbiology of spoilage of fish. Torry research
Station, which had a library on fish technology R&D going back to the
1930's, is regrettably closed down and I cannot carry out a literature
search locally.
Peter Howgate
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