Sorry folks, I omitted to include the text in my message of yesterday. I'll
try again.
Dear Michael
The short answer to both of your questions of 27 October is - No! To expand.
<1. Are there any rapid methods for TVB that he could use in his plant.>
By its nature the analytical procedure for determination of TVB involves
volatilisation of amines. This can be done in simple equipment at room
temperature - the Conway method - but this takes hours. Steam distillation
can be effected in standard laboratory glassware, for example, that used in
the distillation step of the Kjeldahl method, and can be accomplished in
20-40 minutes depending on the design of the equipment - macro or micro. The
distillation units of semi-automated Kjeldahl equipment such as supplied by
Tecator and Büchi have cycle times in the order of 10 minutes, which is the
fastest I have come across. However this type of apparatus is expensive and
probably not justified just to carry out TVB's in a fish processing plant.
Apart from the analytical step, there is the time required for sampling and
preparing the sample for analysis, about 30 minutes at best. Sampling a
heterogenous material like fish waste, unless is it already comminuted and
mixed, will be a problem of itself.
<2. If not are there any other rapid methods that he might use for fish
waste to determine quality.>
What aspects of quality, what is the nature of the wastes? If freshness is
the main criterion, then sensory assessment is rapid enough. My, somewhat
limited, contacts with quality managers of pet food manufacturers using fish
in their products is that the raw material must be fresh and without any
signs of microbiological spoilage. Cats can be very fussy eaters! (We had a
pet cat which had a cut off of acceptability of cod and similar species of
around 4 days in ice. More than this and an exploratory sniff would result
in her stalking, disdainfully as only cats can, out of the kitchen, tail
upright and rigid, into the garden to look for something still warm and
fresh. I often wondered if I could recruit her into my laboratory sensory
panels and use the stiffness of the tail as an index of freshness). One
contact I had with a British pet food manufacture was to brief a group of
quality controllers on sensory evaluation of fish. My advice would be for
the fish processing company to specify the freshness of fish, say, less than
the equivalent of 6 days in ice for demersal species, from which wastes
could go for use as pet food, and to include waste handling and storage in
the company's Quality Assurance programme. This might satisfy the customer
without the requirement of carrying out TVB determinations. TVB is a lousy
method for assessing the freshness of fish products, and the principle that
continuous process control is more effective than end product inspection in
achieving required quality applies to material for pet foods as it does for
material for human food.
Peter Howgate
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