Integrierte Vermeidung und Verminderung der Umweltverschmutzung

Chapter 2
Skinning and cutting involves removing the edible parts of the fish and cutting it into pieces of
the appropriate size. Skinning can be done manually or automatically. With automatic
operations, white fish are skinned by pulling the fillet over an automatic knife, whereas fatty
fish are skinned by pulling the fillet over a freezing drum. Then, fish are transported, e.g. by
fluming, to cutting tables from the holding vessels and then eviscerated, i.e. head, tails and
inedible parts are removed. In small fish, such as sardines, only heads and tails are removed,
and for medium sized and large fish the guts are removed as well. For white fish, this stage just
involves the removal of the fillet flesh, whereas for oily fish the process involves gutting, deheading
and removal of fillets.
Fish and shellfish are processed and preserved by a large variety of methods and may be
consumed in their primary form, raw or cooked. They may also be further processed to produce
fish or shellfish-based foods, such as moulded products or prepared dishes. Some preservation
methods involved in fish and shellfish processing include freezing, chilling, canning, curing,
drying, smoking, fermenting and MAP.
2.2.2.1 Frozen processed fish/moulded fish products and fish fingers
During processing, frozen fish blocks, made from either layered fillets, jumbled or minced fish,
are cut into the required dimensions. With moulded products, the fish off-cuts, seasoning and
binding materials are fed into a moulding machine and formed into the required shape. The
product then passes through a series of enrobing machines, which cover the fish with batter
and/or breadcrumbs, with the type and number of enrobers being dependent upon the desired
product. After enrobing, the product is fried in an edible oil. Temperatures vary but
around 190 °C is typical. The fryers may be heated by thermal oil, gas or by electrical means.
The fried product then travels into a freezing unit where it is subjected to a stream of cold air to
reduce the product to a predetermined target temperature, -18 °C is typical.
2.2.2.2 Canned fish/shellfish products
Raw fish are washed, cut into fillets and then steamed in cooking/cooling tunnels. After head
removal, white fish are filleted in machines with two sets of rotating knives that cut the fillets
from the bone and cut off the collar bones. The knives are watered to cool them and to clean off
fish meat and scale.
Next, the two fillets are conveyed skin-side down to the skinning phase. Fatty fish are orientated
in a forward direction and held into position, using water jets, until aligned with a stop plate.
They are de-headed and the tails and guts are taken out before entering the filleting machine.
The two fillets then proceed to the skinning stage. Filleting and skinning may be carried out
manually. Descaling is sometimes achieved using caustic baths. Fish off-cuts are normally
transported to the waste collection area via chutes, water flumes or conveyor belts.
After steaming, the fish are filled into cans, which contain either brine, oil or sauce. The cans
are sealed by passage through a can seamer. Precooking, skinning and cutting are carried out if
medium size or large fish are processed. Small fish are put in cans whole and are cooked
directly in the can.
After seaming, the cans pass into a retort for sterilisation. Here, the product is heated at a
sufficient temperature to inactivate any food poisoning micro-organisms. The product is then
cooled with chlorinated water. Shellfish are processed in a similar manner but are often
transported under a rocking motion through a scalding system to open the shells and dislodge
the flesh. Additional washing and trimming steps may also be incorporated to remove sand and
mud.
The curing and smoking of fish and during processing of shellfish, may also be carried out.
68 January 2006 RHC/EIPPCB/FDM_BREF_FINAL