Integrierte Vermeidung und Verminderung der Umweltverschmutzung

Chapter 2
Flexible films are formed from non-fibrous plastic polymers, which are normally less than
0.25 mm thick. Typical materials used for flexible films are PE (polyethylene), LDPE (low
density polyethylene), PP, PET, HDPE, PS, and PVC. In general, flexible films are relatively
cheap; they can be produced with a range of barrier properties; they are heat sealable; add little
weight; can be laminated to paper, aluminium and other plastics; and are easy to handle.
Flexible films are used for packaging a large range of both wet and dry food products.
Finally, paper and board can be produced in many grades and many different forms. It is
recyclable and biodegradable and can easily be combined with other materials. Laminated
cardboard packs are used on a large scale for milk and fruit juices. Paper and board are also
extensively used for food packaging and often as secondary packaging.
An important step in the packing process is the sealing of the container or packs. The
maintenance of the food quality depends largely on adequate sealing of the packs. Seals are
usually the weakest part of the packs and also suffer most frequent faults during production, e.g.
when food is trapped in a seal, incorrect sealing temperatures or incorrect can seamer settings.
Cans are seamed and bottles and jar glass are sealed with metallic caps, plastic caps or cork.
Form-fill-sealing is now a well established technique. In this process, the container is formed
and partly sealed, filled and then finally closed by full sealing.
The requirements for filling are accuracy, to ensure that the required amount of product is
packed and hygiene, to ensuring that the product is hygienically filled at the correct temperature
to guarantee the highest possible quality and optimum shelf-life. The selection of an appropriate
filling technique depends on the nature of the product and the production rate required. The
filling can be by level, volume or weight.
Level filling is most frequently used in the drink industry, expecially for beer. Volumetric
filling is applied to liquids, pastes and powders. The most common is the piston filler. Finally,
weight filling is applied to large particulate materials, e.g. confectionery. These are filled into
containers using a photoelectric device, to count individual pieces. Also multi-head weighers are
being developed which aim to weigh different products simultaneously, prior to filling into the
same container.
Containers need to be filled accurately without spillage and without contamination of the seal.
The filling of liquid foods like milk and fruit/vegetable juices can be categorised by the
temperature of the food at the time of filling, e.g. hot, ambient or fresh cold filling, or as aseptic
filling. The temperature ranges involved in the filling process are best illustrated by the hot
filling and fresh cold filling processes. Hot filling is undertaken at temperatures of up 95 ºC, to
inactivate certain relevant micro-organisms, whilst many drink products are formulated with
ingredients that do not need to be heat treated to be microbiologically safe and these are,
therefore, fresh cold filled at between 0 and 5 ºC. For aseptic packing, pre-sterilised, e.g. by
hydrogen peroxide, containers are necessary, and the filling needs to take place in a sterile zone.
2.1.8.2 Gas flushing and storage under gas (H.2)
2.1.8.2.1 Objective
Gas flushing is a process in which products are stored in an artificially produced atmosphere,
normally within a plastic container such as a hermetically sealed tray or pouch. The process is
also referred to as modified atmosphere packing (MAP), and is used to enhance the colourretention
of, e.g. fresh meat or cured meats such as bacon and cooked ham, especially in sliced
form. MAP is also applied to extend shelf-life. The impact of MAP depends on the combination
of product, packaging materials and gas mix.
Storage under gas is applied to wines. Inert gas is applied to wines in tanks in place of sulphur
dioxide (SO2). This is carried out to preserve an adequate CO2 content and the organoleptic
qualities of the wine, to protect it from oxidation, and to the prevention of bacterial deviations.
It also allows the prevention in the alteration of tanks which would be emptied, e.g. in the case
of bulk sales to private individuals. Finally, it permits the conservation of sterile fruit juices.
50 January 2006 RHC/EIPPCB/FDM_BREF_FINAL