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Atomic layer deposition (ALD) is a surface controlled layer-by-layer process based on self-limiting gas-solid reactions. Thin films are prepared using volatile precursors in repeating cycles until a preferred film thickness is obtained. ALD is suited for producing dense and pinhole-free inorganic films uniform in thickness. Most important commercial applications lies today in microelectronics, but they range from displays to protective coatings on silver jewellery. The purpose of this presentation is to demonstrate both the potential and the challenges of using ALD to create thin barrier layers for packaging materials. ALD can have a profound effect on the barrier values of various polymer films and polymer coated paperboards. As far as safety issues are concerned, these thin barrier films seem not to fall under the European definition of nanotechnology and migration is low enough to meet the requirements set by current European regulations. ALD can also be used to create antimicrobial thin films, and thin oxide films can be modified for improved mechanical and surface properties. It is recommended that ALD deposited thin films are protected with an additional polymer layer also providing heat sealability. Although ALD is today carried out in batch mode, the development of roll-to-roll processes will enhance the techno-economic feasibility of ALD, among others, for packaging materials.

The possible application of several multilayered biobased materials for packing different food products, ranging from short to long shelf life products, was investigated. Several transparent and metalized cellulose based film, a cellulose/PLA based film, a xylan based film and PLA trays with a PLA based film, a PLA/cellulose based film and a PLA/paper based film as topfilm were examined. The investigated food products were tomatoes, steak, French fries, ham sausage, filet de saxe (a raw cured pork meat product) grated cheese, tortillachips, rice cakes, dry biscuits and potato flakes all packed under air or modified atmosphere (MAP). The food products were stored at refrigerated (4°C) or room temperature and analyzed at certain points during their shelf life. For the short shelf life products, microbiological analysis (total plate count, lactic acid bacteria and yeast and moulds), gas composition of the headspace, color, aw and pH were followed and those quality parameters were each time compared with their evolution in the conventionally packaged food products. For the medium shelf life products also hydrolytic and oxidative lipid rancidity were monitored. For the long shelf life products no microbiological analysis were performed. Furthermore, sensory characteristics of the different food products were evaluated. From the storage experiments it could be concluded that most investigated biobased materials are good functional substitutes for the conventional packaging materials currently used. For example, the oxygen and carbon dioxide concentrations followed the same trend as in the reference film and the concentrations remained below the maximum limit or above the minimal limit during the entire shelf life of the food products.