The nitrogen factor (the percentage of nitrogen in the raw
flesh) was determined on 70 samples of scampi taken on a total of nine
fishing trips to two fishing grounds over a period of 16 months. A
representative sample of the catch from each fishing trip was classified on
board the fishing vessel for size, sex and shell condition. Selected
samples were placed in plastic boxes, sealed and stored on ice until
landing (the ice did not come into contact with the animals) when 500 g
samples were sealed into plastic bags and blast frozen at −20 °C.
The samples were stored at −20 °C until thawed in the laboratory
prior to analysis. The objective was to produce a figure for the nitrogen
content of the separated meat portion which represented the composition of
the material ‘fresh from the sea’. Samples were analysed for
fat, moisture, ash and nitrogen content by standardised procedures. It is
known that changes in composition can take place during commercial handling
and processing of the whole scampi and the figure obtained in this exercise
would therefore represent a standard for comparison with the commercially
processed material.
The nitrogen content was significantly higher and the moisture content
significantly lower in hard-shelled scampi than those with thin or soft
shells. However, taking into account the distribution of the shell type in
the catches an overall figure of 2.90 is recommended for the nitrogen
factor of scampi fresh from the sea.
In commercial fishing practice the heads of the scampi are removed on
board the fishing vessel and discarded and the tail portions are packed in
plastic fish boxes which are sealed and stored in ice. In parallel with the
investigation carried out by the Analytical Methods Committee on the
composition of scampi fresh from the sea, the Sea Fish Industry Authority
carried out an exercise to determine the proximate composition of the tail
meat during commercial processing. Samples were taken at all stages during
the processing operation and these sample were analysed by the same
laboratories as had analysed the samples of scampi fresh from the sea and
working to the same QC standards. This work is reported in the
Appendix.