Evaluation of volatile organic compounds related to board based packaging by use of instrumental and sensory analysis

Abstract: The main topic of the thesis is characterisation and evaluation of volatile organic compounds emitted by packaging materials based on paperboard products. The properties and concentration of these compounds are critical to how well these materials perform when applied as a main component of food packaging. Specifically there is an interest for finding out whether the materials are neutral enough from a flavour and odour perspective. This means that the odour and flavour of the packed foodstuff must not be influenced in a nonacceptable way by the packaging.The studies may be seen as divided into two main parts complemented with an additional study. In the first part ”Electronic noses”, based on quite a number of gas sensors of different sensitivity profiles, conventional gas chromatography and to some extent also sensory analysis were applied for evaluating the volatile organic compounds emitted from paperboard products. The results obtained from the ”electronic nose” measurements were evaluated in the light of the detailed chemical information provided by the gas chromatography. First a large number of paperboard products were analysed followed by analysis of some thirty sequential jumbo reels of two different board products. The obtained results clarified what could be achieved when applying the gas sensor based analytical system to this type of materials. Furthermore the experiences gained by the experiments pointed out the importance of managing sample handling, headspace generation and gas flow distribution in a good way. These findings were useful for managing a third experimental series in which a commercial gas sensor based system was applied for differentiating aqueous thyme solutions regarding the thyme concentrations.The multivariate data analysis methodology used for evaluating the gas sensor responses was successfully applied also to the obtained gas chromatography data. The chosen approach was to treat the chromatograms as having been generated by a large number of sensors. The sensory analysis was applied for investigating whether the found differences were relevant from a taint perspective which was invaluable since the ”electronic nose” system and our human chemical senses work according to different principles. It was therefore especially interesting to find out that the “electronic nose” and off-flavour differentiation between sequential jumbo reels of one product agreed well. Furthermore it was clearly not just a matter of different humidity of the materials.In the second part the sensory analysis was the mainly applied evaluation technique. Gas chromatography was very valuable for supporting the experimental work and contributing to the understanding of the results whereas no gas sensor related evaluations were performed. In the first part a need for investigating a number of issues more carefully was pointed out. Topics such as sensory sensitivity, perception of mixtures in relation to the mixture components and calibration of sensory analysis were consequently investigated. For managing it was necessary to restrict the studies to simplified model systems that were arranged based on results and experiences obtained from studies of real packaging systems. The results pointed out the complexity of sensory related packaging issues and help in improving these type of sensory analysis e.g. by suggesting calibration procedures. The additional study is related to active packaging which means that the intention with the packaging is to influence the packed foodstuff in a way that is favourable and desired. In this study odorants were added to dispersion coatings that well could be used in the paperboard products. Headspace gas chromatography was successively applied for measuring the amounts and coating retention of the odorants upon drying. Furthermore multivariate data analysis was useful for overviewing the results and finding relations and structures that otherwise were hard to see.