Integrierte Vermeidung und Verminderung der Umweltverschmutzung

Chapter 2
2.1.7.3.2 Field of application
The technique is used, e.g. for drying coffee extracts, spices, soup vegetables, instant meals, fish
and meat.
2.1.7.3.3 Description of techniques, methods and equipment
The freeze-drying equipment consists of a drying chamber with temperature controlled shelves.
This can be a batch chamber, where the trays remain fixed on the heating plates through the
drying operation, or a semi-continuous type, in which the trays move through a vacuum lock
into a drying tunnel. The equipment also includes a condenser, to trap water removed from the
product in the drying chamber and to facilitate the drying process; a cooling system, to supply
refrigerant to the shelves and the condenser, and a vacuum system, to reduce the pressure in the
chamber.
If the incoming product is a liquid, e.g. coffee extract, it is frozen in two steps, at two freezing
temperatures and times, and then it is ground. The solid material is then fed manually or
mechanically onto the trays in a drying chamber. The temperature of the drying chamber is well
below 0 °C. The exact temperature depends on the product being dried. A vacuum is applied in
the chamber. The ice evaporates under these conditions. This evaporation causes a further
decrease in the temperature of the product, which is compensated for by adding heat by means
of heating plates to the product through the temperature controlled trays. The evaporated water
is refrozen on the surface of a condenser, which has a temperature well below the sublimation
temperature under the existing conditions in the chamber. From time to time the condenser is
de-iced by heating the condenser surface. The water is liquified and drained. The vacuum is
maintained by a vacuum pump. The outlet of the vacuum pump is emitted into the air. To
prevent solids entering and damaging the vacuum pump, a filter is usually applied in front of the
pump.
2.1.8 Post processing operations (H)
2.1.8.1 Packing and filling (H.1)
2.1.8.1.1 Objective
The objective of packing is to use any products made of any materials of any nature for the
containment, protection, handling, delivery and presentation of goods. Packing may be applied
to raw materials and to processed goods. Filling is the process of putting the product in the
package in a proper way.
2.1.8.1.2 Field of application
The majority of food products are packaged before they enter the distribution chain. In some
cases packing is an integral part of the production process, which means that the packaged
product is further processed. An example of this is the canning and bottling of foods and
subsequent heat conservation.
48 January 2006 RHC/EIPPCB/FDM_BREF_FINAL