Integrierte Vermeidung und Verminderung der Umweltverschmutzung

Chapter 2
2.1.2.1.3 Description of techniques, methods and equipment
A large variety of equipment is available, normally adapted to the product to be processed.
Equipment can be power or hand-operated, depending on the size of the operations.
Cutting is used for size reduction of large to medium sized materials. Knives, blades, cleavers
or saws are usually used for cutting. Cutting is an important operation in meat and fish
processing. The cutting of meat is used post slaughtering to dress and split carcases, to remove
offal and to remove appendages and is covered in the “Slaughterhouse and animal by-products
BREF”. At meat installations, carcases are further reduced into retail cuts of joints by the
removal of bone, skin and fat. Meat prepared for further processing into, e.g. ham, bacon or
sausage, is initially treated in a similar manner to fresh meat, and will then be subject to further
processing operations. These may include deboning, derinding, defatting, slicing, chopping,
mincing and emulsifying. The cutting equipment used in meat processing includes power
operated cleavers, circular or straight saws for splitting carcases, and band saws for the further
reduction of the carcases. These are all electrically operated. Special derinding machines are
used for separating rind and fat from pork. The cutting of potatoes for the production of potato
chips often involves the use of hydro cutters where the potatoes are conveyed by water at high
speed over fixed blades.
Slicing produces pieces of material of equal thickness. Slicing equipment consists of rotating or
reciprocating blades which cut the food when it passes beneath. Sometimes the material is
pressed against the blades by centrifugal force. In other cases, e.g. for slicing meat products, the
material is held on a carriage as it travels across the blade. Hard fruit, such as apples, are
simultaneously sliced and de-cored as they are forced over stationary knives inside a tube. In the
sugar industry, sugar beets are cut into thin slices, called “cossettes”.
A variant of slicing is dicing and is applied to meat, fruits and vegetables. In dicing, the food is
first sliced and then cut into strips by rotating blades. The strips are passed on to a second set of
rotating knives, which operate at right angles to the first set, and cut the strips into cubes.
Chopping breaks down raw materials into small particles. Chopping into a coarse pulp is
applied to meat, fruits and vegetables. In chopping, the material is placed in a slowly rotating
bowl and subjected to a set of blades rotating at high speed. This technique, also called bowl
chopping, is widely used in the production of sausages and similar products. The degree of size
reduction can be varied depending on the knife-speed and cutting time, and in extreme cases,
the material can be reduced to an emulsion if required.
Mincing is mainly used for the size reduction and homogenisation of meat. A meat grinder is
used to mince the meat. This is a lightly constructed screw press with a cutting plate or rotating
knives at its outlet. The process is a combination of cutting and extrusion, where the meat is
passed through a plate with orifices.
Pulping is mainly used for the size reduction and homogenisation of fruit and vegetables. A
moving rough surface ruptures the fruit or vegetables and squeezes the material through a gap
producing an homogenised mass. The most common pulpers are drum pulpers and disc pulpers.
Sometimes the pulping process is used for juice extraction.
Pressing is applied to extract the liquid part of grapes, other raw materials or marc after
maceration. Pressing is used in wine production, for some other alcoholic drinks and for fruit
and vegetable juices.
There are two main types of press. The horizontal pneumatic press comprises an inflated
pneumatic membrane located in the centre of the press. Berries are slowly pressed releasing the
juice, usually known as must in wine, cider and perry making, in a tank, while the solid parts
remain in the press. In a hydraulic compression vertical press, grapes are placed in a cage which
contains them during the pressing. A horizontal tray presses the grapes vertically and the must
which flows through the cage is collected in a tank for further processing. The grapes remain in
the cage. There are also other types of presses, e.g. belt presses and horizontal presses.
14 January 2006 RHC/EIPPCB/FDM_BREF_FINAL