Figure 1: PLA bottles for filling edible oils as a sustainable alternative to PET bottles © Martina HollerBottles made of bioplastic protect cooking oil from oxidative spoilage (rancidity) to a similar extent as PET bottles. In addition, even less taste- and odor-impairing substances were formed. This is the result of a recent study published in the journal "Food Packaging and Shelf Life" by researchers led by Marc Pignitter from the Faculty of Chemistry at the University of Vienna.
To keep healthy cooking oils with a high proportion of unsaturated fatty acids fresh for a long time, the bottle material is crucial. Due to their material properties and low cost, PET bottles are often the first choice for this purpose. However, PET (polyethylene terephthalate) is very difficult to biodegrade and remains in nature for up to 2000 years. With a global production of almost 400 million tons of plastic (2021), only one-third of plastic waste is recycled in Austria, for example, and a quarter of plastic waste also ends up in landfills across the EU. In 2022, the EU Commission therefore called for new EU-wide regulations for a transition to biobased, biodegradable and compostable plastics - a group of substances that the research team around food analyst Marc Pignitter at the Institute of Physiological Chemistry at the University of Vienna is working on intensively.
Renewable & Sustainable A promising candidate for bioplastic bottles is polylactic acid (PLA) - a thermoplastic biopolymer derived from renewable raw materials that is also industrially compostable. It is obtained by fermenting carbohydrates in corn starch or sugar cane and is already used successfully in the food industry, for example to fill smoothies. The research team now investigated whether bioplastic bottles made of PLA could also be used to store cooking oils, which would be a decisive advantage in terms of sustainability & environmental compatibility given that around 200 million tons of cooking oil are produced worldwide.
In detail, the effects of different conventional plastic packaging materials as well as of the bioplastic PLA on the oxidation stability and shelf life of sunflower oil were compared. The focus was on the packaging-induced development of oxidation products in the Él, which are responsible for the rancidity and bitter taste. In addition, the compounds that leached from the bottle materials into the Éle were analyzed.
Advantageous & sustainable The results of the storage study showed that bioplastic bottles made of PLA even protected the sunflower oil from becoming rancid better in some cases than conventional PET. In addition, unlike PET bottles, PLA bottles were not found to transfer "unintentionally introduced substances" (NIAS) into the Él - so all in all, two more advantages in addition to the sustainability of the material. Although PLA is currently still well above (recycled) PET in terms of cost, the push towards bioplastics and the associated scalability will have a price-reducing effect and bring PLA into focus as a real alternative. Since PLA can already be partially recycled, it would also have to be taken into account in waste management.
Publication in Food Packaging and Shelf Life:
Holler M, Alberdi-Cedeño J, Auñon-Lopez A, Pointner T, Martínez-Yusta A, König J, Pignitter M. Polylactic acid as a promising sustainable plastic packaging for edible oils. Food Packag Shelf Life, 2023, 36, 101051 2023,
DOI: 10.1016/j.fpsl.2023.101051
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