Comparative life cycle analysis of a biodegradable multilayer film and a conventional multilayer film for fresh meat modified atmosphere packaging – and effectively accounting for shelf-life

Life cycle analyses of novel food packaging materials do not often account for the environmental impact of a change in shelf-life, which can result in misleading comparisons. This paper established a methodology for comparative life cycle analyses, whereby the direct effects of the lidding films were compared whilst ensuring the indirect effects of the wasted food portion remained stable. Global warming potential and non-renewable energy use were analysed for a conventional (low-density polyethylene/ethylene vinyl alcohol) versus a biodegradable (polyhydroxyalkanoate/butenediol vinyl alcohol) multilayer lidding film for modified atmosphere packaging of minced beef. Two methodologies were investigated. The first (metric one) changed the barrier layer thickness in the biodegradable film to match the carbon dioxide transmission rate with that of a conventional film. The second (metric two) changed the barrier layer thickness to match a carbon dioxide transmission rate predicted by a mathematical model to ensure the same shelf-life as the conventional film. Using metric two over metric one resulted in 1) a thinner film 2) 2.3 times lower global warming potential. When using sugar beet as the biopolymer feedstock and the current UK disposal system, the biodegradable film had 135% higher global warming potential than the conventional film. By incorporating waste products and better farming practices, the global warming potential of the biodegradable film could be up to 92% lower than that of the conventional film. This work demonstrates how shelf-life can be incorporated into life cycle analyses and the importance of accounting for it, in particular when evaluating biodegradables which often have higher permeabilities.