Sustainable food packaging to combat lipid oxidation in edible oils

Abstract: In order to determine whether a sustainable packaging material could be used as an alternative to polyethylene terephthalate (PET), this study investigated the influence of a renewable and/or biodegradable packaging material on the oxidative stability of sunflower oil.

Two renewable packages consisting of polylactic acid (PLA) and bio-polyethylene (Green-PE) were compared with conventional packaging consisting of PET, recycled PET (r-PET), and polyethylene (PE). The study was carried out over a two-month storage period at room temperature and under the influence of light. The oil samples were taken on days 1, 3, 7, 14, 27, and 56 of storage, and the peroxide value, p-anisidine value, specific secondary products of lipid oxidation, the content of tocopherols and migration of the packaging materials were determined using ¹H-NMR, GC-MS and LC-MS.

The results showed that the degree of lipid peroxidation in PLA-stored sunflower oil barely differed from the oil samples stored in r-PET and PET, while it was significantly higher in oils packaged in PE and Green-PE compared to PLA. Interestingly, the storage-induced formation of (E)-2-heptenal and pentanoic acid was even less pronounced in sunflower oil stored in PLA than in other bottles. For the tocopherols, no difference could be detected between oils filled in PLA, r-PET, and PET bottles. Benzene as a migration product was found in oil stored in r-PET (0.138 ± 0.004 μg/L) and PET (0.133 ± 0.005 μg/L) after 56 days. It was not detected in the other plastic materials. Furthermore, no migration compounds from PLA were observed in the oil samples.

As PLA bottles could prevent lipid oxidation to a similar extent as r-PET and PET packaging without releasing migration compounds to the oil, PLA could be used as a renewable and non-fossil packaging material for edible oils and thus reduce the environmental impact.