fillets or mince. However, chilled fish mince has a very short PSL, and should always be transported in the frozen state.
Regulations,standards
In the EEC Council Regulation 103/76 with later amendments, common market-ing standards for certain fresh or chilled fish are laid down with rules for freshness and size categories.
In the EEC, the Labelling directive ap-plies, see section 6.2 in chapter 1.
Codex Alimentarius recommended code of practice for fresh fish (CAC/RCP 9-1976) states that fresh fish should always be carried in melting ice. In order to allow the ice to melt, the temperature in the
storage room must be a few degrees above 0°C.
Codex Alimentarius has also issued Rec-ommended Codes of Practice for:
Shrimps or Prawns (CAC/RCP 17-1978), Lobsters (CAC/RCP 24-1979), Minced fish prepared by mechanical separation (CAC/RCP 27-1983), and Crabs (CAC/RCP 28-1985), as well as a Rec-ommended Code of Hygienic Practice for Molluscan shellfish (CAC/RCP 19-1978).
Minimum requirements.
Raw materials
The fish must be of good and sound quality prior to the chilling process.
The chilling process should be started as quickly as possible in order to minimize growth of microorganisms. Further infor-mation on fish is given in section 2.2 above.
The best way of maintaining fresh fish at a
CHILLED FISH
127
5.5 CHILLED FISH
temperature close to 0°C is to keep it in melting ice in a room with a temperature of 1-3°C. If the thermostat in the room is set at 0°C, the air temperature may occasion-ally fall below 0°C which will prevent the ice from melting. This will inhibit cooling of the fish and cause some parts to freeze.
Superchilling (also called deep chilling or partial freezing) to around -2°C may give a longer storage life, but this method is seldom used.
Processing
Processing, e.g. filletting, should be
hy-gienic and follow the Codex documents mentioned above, see also the Codex doc-uments referred to in section 3.3 above.
Packaging.
Fresh fish is often marketed unpacked, with ice in the retail tray.
Vacuum-packaging or VSP of fish in plastic pouches is a good form of retail packaging. For fatty fish the oxygen per-meability should be low as this will in-crease PSL due to lower oxidation of the lipids. Trout stored at 0°C (in ice) packag-ed in PE (high oxygen permeability) could
CHILLED FISH
6
4
2
-5 0 5 10
°C PSL, days
8 10 12
Cod fillets
PSL-diagram for chilled cod fillets at different storage temperatures
Temperature.
Storage without melting ice (or storage at temperatures above 0°C) will increase the activity of bacteria and lead to rapid spoilage. Bacteria able to cause food poi-soning may develop in fish which are not well iced. Clostridium botulinum type E which is often found in fresh fish, can pro-duce toxins at temperatures down to 3.3°C, see table 3.1. Clostridium bo-tulinum can only grow under anaerobic conditions, i.e. where the oxygen concen-tration is very low. Therefore, vacuum-packaging of fish products in plastic ma-terials with low oxygen permeability and
the use of MAP with no oxygen, necessi-tates product temperatures below 3.3°C.
The toxin from Clostridium botulinum type E and harmful bacteria such as Vibrio will be destroyed under normal cooking.
However, with fish products intended to be eaten raw such as sushi or oysters, or to be used as raw materials for the manu-facture of lightly preserved fish products, such as gravad fish and cold smoked fish (see section 5.6 below), it is very impor-tant that the fish is consimpor-tantly well iced.
Heat stable histamine may be formed, in fish of the tuna and mackerel type if they are not stored at low temperatures.
CHILLED FISH
129 Temperature limits
Ideal temperature: in melting ice (0°C to -0.5°C) Legal requirements for transport:
ATP: In melting ice, i.e. 0°C
EEC: the temperature of melting ice, i.e. 0°C.
Sensitivity
Temperature
Whole gutted plaice ★★★
Cod fillets ★★★★
Mince ★★★★★
develop a markedly rancid taste after 8 days. For trout vacuum-packed in a plas-tic material with low oxygen permeability the PSL at 0°C is about 20 days.
Vacuum-packaging of lean fish gives a slightly longer PSL, but as mentioned in section 2.2 above, the advantage comes
when the fish is only of secondary quality.
MAP is used in some countries, with 30%
oxygen, 40% carbon dioxide and 30% ni-trogen for lean fish, and 60% carbon di-oxide and 40% nitrogen for fatty fish.
However, MAP makes cooling of the fish more difficult than with vacuum-packag-ing.
Description
This group contains a wide variety of fish products with regional variations. The fish has been treated by one or more of the following treatments: salting, smoking, marinating, heating or addition of preser-vatives. Such fish products have a longer PSL than fresh fish. Lightly preserved fish products are cold smoked lightly salted salmon, gravad halibut and shrimps in brine. Semi-preserved products are her-ring fillets in a marinade with a pH lower than 5, and salted cod.
Regulations,standards.
The only international standard for the transport of preserved fish products is the Codex Recommended international code of practice for smoked fish (CAC/RCP 25-1979). This recommends that smoked fish which is not treated in such a way as to prevent the outgrowth of Clostridium bo-tulinum type E, should be kept at a
tem-perature below 3.3°C. Codex Alimentarius has also issued a Recommended Practice for Salted fish (CAC/RCP 26-1979).
In some countries, vacuum-packed fish products must be kept below 3°C, and some countries do not allow chilled vacu-um-packed smoked fish, simply because of the risk of Clostridium botulinum type E (in these countries such products must be marketed in the frozen state).
In the EEC countries, the Labelling direc-tive applies, see section 6.2 in chapter 1.
Minimum requirements.
Raw materials.
The raw materials must be of good and sound quality and be of the required de-gree of freshness.
The processing must be in accordance with good manufacturing practice, and should result in the desired characteristics, e.g.
salt/water ratio, temperature, concentration of preservatives, pH, etc.