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S16 Slurry Ice System
Follow through project work
Lunar Filleting – Peterhead.
After the catch was discharged in Ullapool the fish were transported
to the north-east in refrigerated vehicles. As is normal practice when
landing the majority of fish landed in boxes are auctioned on Peterhead
Fishmarket while the fish landed in bins are contract sold to a small
number of buyers. As part of the trial project work was arranged between
the Master of Challenge II UL33, Seafood Scotland and Lunar Filleting,
Peterhead, for follow through work to be carried out on the catch at the
factory in Peterhead.
During the fishing trip two batches were compiled, each batch consisting
- Two bins of small haddock containing 420kg each (liquid & flake
- 10 boxes of small haddock, each containing 40kg (5 liquid & 5
Batch 1 was packed at 1800 hours on 26th February.
Batch 2 was packed at 0300 hours on 1st March.
Quality evaluations and temperature checks were made in the factory
of Lunar Filleting.
Below: Quality and temperature observations at
Lunar Filleting, Peterhead
Temperature observations •
- The temperature of the fish stored in liquid-ice was consistent.
- The fish stored in liquid-ice was generally colder than the fish
stored in flake ice.
- Only one temperature, the fish stored in flake ice, in boxes,
had a temperature above zero
- The factory workers handling the fish noticed a considerable
temperature difference with fish stored in liquid-ice.
Quality and fillet observations.
After temperature checks were taken the fish were then tipped into a
hopper to check the quality of the fish throughout the bin. •
- There were no signs of freezing in the fish stored in liquid-ice
although the temperatures recorded were -1°C.
- There were slight signs of damage to the fish caused by the
- It was agreed, by all present, that the fish stored in
liquid-ice had a fresher appearance than the comparative bin.
- The fish stored in liquid-ice were firmer.
A sample of fish from each bin of batch 1 was filleted to ascertain
whether any visual difference were evident. Approximately 6 fish were
filleted from each bin.
- Very little visual difference
- Fish stored in liquid-ice had fewer blood spots
- Fish stored in flake ice were slightly softer, probably due to
Below: Sample of fillets in the laboratory in Lunar Filleting
Follow through work:
Trial involving fish kept in cold storage
The final part of the project work involved fish being kept in cold
storage until they were unfit for human consumption. Seafish arranged to
purchase two bins of small haddock from the catch of Challenge II UL33.
Both these bins were filled with 420kg of fish, from the same fishing
operation, with fish from one bin stored in liquid-ice and fish from the
other stored in flake ice. The fish purchased by Seafish were packed at
1300 hours on the 26th February. Upon discharge of the catch in Ullapool
the fish were transported to the premises of Stephen Buchan, in
Peterhead, where they were kept in cold storage.
After daily checks on the quality of the fish from both bins it was
agreed with Gavin Thain, Master of Challenge II UL33, that the fish
should be thoroughly inspected on 11th March 2003, when the fish was 13
At 0900 hours on 11th March the fish were thoroughly inspected to
assess differences in the shelf life of the two samples. A number of
temperature checks were taken from both bins and each bin was tipped
into another bin so visual differences could be evaluated throughout the
Temperature checks being taken from the
bottom of the bin
13 day old fish being tipped in the yard of
Stephen Buchan, Peterhead
Range of temperature checks
Temperature observations •
The average temperature of fish stored in
liquid-ice was -0.5°C • The average temperature of fish stored in flake
ice was +0.3°C • The average temperature of fish from the middle and
bottom of the liquid-ice bin was 1°C colder.
Quality and fillet
Quality observations were taken from each bin as the bins
were being tipped, by a forklift, into another bin. Details as follows:
- Eyes – the eyes of the fish from both bins were sunken, although
to a lesser extent with the fish stored in liquid-ice
- Skin – The skin from the fish stored in liquid-ice were of a
better quality, with severe fading from fish stored in flake ice.
- Gills – The gills from the fish held in liquid-ice were turning
pink in comparison to pink/brown gills from the fish held in flake
- Firmness – Fish stored in liquid-ice were firmer than the
- Mucus – The mucus was yellow on the fish stored in flake ice, in
comparison to clearer mucus on fish held in liquid-ice
- Fillets – No visual differences in the fillets were
Although both bins of fish were in remarkably good condition,
considering the age, it was apparent that the fish stored in liquid ice
were of a better quality than the fish stored in flake ice. It is
estimated that the fish from the bin of liquid-ice showed a longer shelf
life of approximately 2 days. The improvement in shelf life is down to
the initial temperature reduction when the fish are stored in the fishroom after the onboard handling.