Integrierte Vermeidung und Verminderung der Umweltverschmutzung

2.1.5.7.3 Description of techniques, methods and equipment
Chapter 2
The tempering process involves the melting of all the fat crystals present by heating to at least
40 °C or above, then cooling the mass to typically below 30 °C, known as the seeding
temperature. This allows formation of stable crystalline forms, which, on holding, enables a
further desirable transformation to occur. Finally the mass is warmed slightly to melt out any
remaining unstable crystalline forms and to establish further crystallisation of the stable forms.
Depending on the particular recipe or formulation, temperatures and holding times will vary
accordingly to ensure the optimum product quality.
Single stream tempering uses the standard technique of inducing crystallisation of the stable
forms from liquid followed by changes in temperature. The product is carried by a conveyor
screw feed into a tempering tube where it is tempered in three stages.
Twin stream tempering requires an already seeded stream to be introduced into a molten
untempered chocolate stream.
Finally, multistage tempering is based on gentle cooling to produce seed crystals, followed by
gentle reheating to allow the formation of stable crystalline forms. The cooling and reheating
zones are made up of multistages maintained at the required temperature ranges via a jacketed
recirculating water system. Various tempering machines are available based on this principle
and are widely used in industry for a wide range of applications.
2.1.5.8 Pasteurisation, sterilisation and UHT (E.8)
2.1.5.8.1 Objective
The conservation of food and feed products is achieved by the killing of the micro-organisms
present. Heat treatment for the conservation of products is one of the main techniques used in
the FDM sector. Heat treatment stops bacterial and enzyme activity and so prevents loss of
quality and reduces food perishability. In heat treatment processes, various time/temperature
combinations can be applied, depending on the product properties and shelf-life requirements.
Pasteurisation is a controlled heating process used to eliminate viable forms of any microorganism,
i.e. pathogen or spoilage causing, that may be present in milk, fruit-based drinks,
some meat products, and other foods, or to extend shelf-life as is the case with beer. A similar
controlled heating process, referred to as blanching, is used in the processing of fruits and
vegetables. Both pasteurisation and blanching are based on the use of the minimum heat
requirement needed to deactivate specific micro-organisms or enzymes, thus minimising any
quality changes in the foods themselves [87, Ullmann, 2001]. In pasteurisation, generally a
heating temperature below 100 °C is applied.
Sterilisation is a controlled heating process used to eliminate viable forms and spores of any
micro-organism, i.e. pathogen or spoilage causing, that may be present in a preserved food. This
can be achieved by moist heat, dry heat, filtration, irradiation, or by chemical methods.
Compared to pasteurisation, a heat treatment of over 100 °C is applied for a period long enough
to lead to a stable product shelf-life.
UHT is a heat treatment of over 100 °C for a very short time.
2.1.5.8.2 Field of application
Pasteurisation and sterilisation are used to treat all types of FDM products; these include milk,
juices and beer. UHT is applicable to low viscosity liquid products.
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