Extrusion International 5-2017

20 Extrusion International 5/2017 AROUND THE EXTRUSION Precision in seven layers motan conveying and dosing technology at Greiner Packaging GmbH Worldwide, up to 2.5 billion cups of coffee are drunk every day. Much of this is prepared from coffee powder capsule portions in coffee machines. Due to the necessary oxygen barrier to prevent ageing of the coffee due to oxidation, these capsule portions consist of either aluminium or a plastic composite foil with an integrated oxygen barrier. Since 2015, the latter have been produced by the “Greiner Packaging” in Kremsmünster, Austria (Fig.1). For this purpose, a sustainable production concept was developed together with the peripheral equipment manufacturer motan and the Austrian agent Luger. With this concept, the punching waste left over after punching out the deep-drawn capsule bodies is completely fed back into the 7 layer extrusion line in accordance with all quality limits. Fig.1: Capsules made of a 7-layer composite foil are the modern way of storing coffee in portions. The film combines barrier properties and recyclability Photo: Greiner Packaging As coffee is a natural product, like all living matter it is subject to an oxidative ageing process, in particular when exposed to the open air and moisture. In particular, the flavouring substances released during roasting of the coffee and the unsaturated fatty acids in the coffee bean oil oxidise very quickly. This is perceptible by the associ- ated change in taste and smell. The coffee becomes sour and rancid. This applies to both whole roasted beans and ground coffee and happens very quickly. In this way, freshly ground coffee loses up to 60 per cent of its aroma after only 15 minutes. The only way to prevent this is to stop the oxidation reaction as quickly and completely as possible, namely by packaging it in air tight and water- tight containers, such as coffee capsules. Greiner Packaging produces coffee capsules from barrier plastic As mentioned at the beginning, the portion containers consist either of aluminium or plastic, both made of deep- drawn foils. However, without evaluating which is the better packaging solution, there is a significant difference between the two alternatives. Whereas an aluminium foil is a good barrier against almost all external influences, there are only very few plastics which are gas tight and aroma tight. EVOH, an ethylene vinyl alcohol copolymer, offers the best barrier properties against both oxygen and steam. It is just as water tight as an LDPE layer which is 10,000 times as thick. As it is comparatively expensive, it is used centrally as a thin barrier layer within a compound