Odour investigation of granular polyolefins for flexible food packaging using a sensory panel and an electronic nose

A study was carried out of the odour properties of polyolefins destined for flexible food packaging. A total of 25 homo- and copolymers of ethylene and five homo- and copolymers of polypropylene in pellet grade were analysed by a sensory panel. Principal component analyses of sensory data showed a perceptible and quantifiable difference between samples. Generally, polypropylene materials were judged less odorous than the majority of polyethylene pellets, especially the ethylene vinyl acetate copolymers. The feasibility of using a commercial electronic nose, equipped with 10 metal oxide semiconductors, to discriminate between the odour of plastic materials was also explored. Instrumental results were satisfactory and correlated well with panel answers, as shown by partial least-squares regression. Furthermore, application of a cluster analysis made it possible to differentiate polymer odours into strong, medium and weak.