Integrierte Vermeidung und Verminderung der Umweltverschmutzung

Chapter 2
Roasting can be carried out either batch wise or continuously. Typical equipment for batch
roasting are a drum roaster, a column roaster, a rotating disc roaster, a fluidised bed roaster and
a spouting bed roaster. Common to all equipment is that the product is heated and agitated at the
same time. The product can be in direct contact with the hot air, called convective heat transfer,
or in contact with a heated surface, called conductive heat transfer. Usually it is a combination
of both. The cooling takes place in separate equipment. This can be a cooling sieve where air is
pulled through or a spouting bed cooler or any other equipment where the raw product is in
contact with fresh air. Quenching with water can take place in the roasting chamber and
sometimes in the cooling equipment. Cyclones are used as an integral part of the process to
remove dust, mainly consisting of product residues and skins (chaff) before it is exhausted to
the air. The recovered material is then reprocessed. The cooling air is also emitted to the air.
2.1.5.6 Frying (E.6)
2.1.5.6.1 Objective
The objective of frying is to cook in edible oil at temperatures in the region of 200 °C.
Vegetable oil, or a mixture of animal fat and vegetable oil, is normally used.
2.1.5.6.2 Field of application
Raw materials such as fish, potatoes and chicken can be fried, e.g. in the production of products
such as fish fingers, potato chips and chicken nuggets.
2.1.5.6.3 Description of techniques, methods and equipment
The product is fed into the fryer on a slatted belt. The fryer is a horizontal chamber containing
the oil. The product drops into the oil and if it is coated in batter, this expands and brings the
product to the surface of the oil. The slatted belt feeds the product under the main fryer belt,
which takes the product through the fryer and controls the frying time. The take-out belt at the
end of the fryer lifts the product out of the oil, allows drainage and transfers the product to the
inspection and packing belts. Fryers are equipped with a fume extraction fan to eliminate fume
leakage. The frying temperature and time vary according to the product being processed.
Temperatures range from 190 to 205 °C and residence times in the fryer are normally around
35 seconds, but can be as long as 6 minutes.
2.1.5.7 Tempering (E.7)
2.1.5.7.1 Objective
The objectives of tempering are to ensure product quality and appearance, enable handling of
liquid chocolate for various applications, e.g. demoulding, and ensure viscosity control and
enable net weight requirements to be met. Tempering is also the controlled thawing of meats.
2.1.5.7.2 Field of application
Tempering is applied in the manufacture of chocolate and products containing chocolate.
Chocolate formulations containing cocoa butter, or cocoa butter equivalents, need to be
tempered before use. Chocolate may be under-tempered, well-tempered or over-tempered
depending on the particular application.
Tempering is done because cocoa butter can exist in various crystalline forms, which if left
untempered transform into unstable forms that impact severely on production capability and
product quality. The process ensures that the fat is crystallised into stable forms which then
enables products to be manufactured with good gloss and hardness, and to be crispy if needed. It
also delays the formation of grey white spots on the surface known as fat bloom.
38 January 2006 RHC/EIPPCB/FDM_BREF_FINAL