The interaction between plastic food packaging and olive oil
The science results showed a gradual loss of quality during storage, especially in plastic or glass bottles. What's the interaction of polypropylene and polylactide packaging with olive oil? How much olive oil was sorbed into the packaging material?
Four commercial samples of extra-virgin olive oil have been analysed in order to evaluate the influence of storage time on quality.
The following parameters were determined after 3 and 6 months of storage: acidity, peroxide index, absorption coefficients K270 and K230, percentage of humidity, impurity content (%), phenols content, iodine index, saponification index, colour index and fatty acid content. At the same time, the effects of container type on the deterioration in quality were studied.
Each olive oil was stored in five different containers at room temperature with the same surface area of exposition to air and light: clear PET bottle, PET bottle (covered with Al foil), glass bottle, tin, and Tetra-brik®. The results showed a gradual loss of quality during storage, especially in plastic or glass bottles. The best containers for commercial packing of extra-olive oil were tin and Tetra-brik®.
The plastic packaging has gained worldwide spread for the storage of olive oil. However, plastics are not inert and interaction phenomena may occur between packaging materials and olive oil.
Some extra virgin olive oil samples were submitted to accelerated interaction conditions, in contact with polypropylene (PP) and polylactide (PLA) plastic packaging materials. 3D-front-face fluorescence spectroscopy, being a simple, fast and non destructive analytical technique, was used to study this interaction. Independent components analysis (ICA) was used to analyze raw 3D-front-face fluorescence spectra of olive oil. ICA was able to highlight a probable effect of a migration of substances with antioxidant activity.
The signals extracted by ICA corresponded to natural olive oil fluorophores (tocopherols and polyphenols) as well as newly formed ones which were tentatively identified as fluorescent oxidation products.
Based on the extracted fluorescent signals, olive oil in contact with plastics had slower aging rates in comparison with reference oils. Peroxide and free acidity values validated the results obtained by ICA, related to olive oil oxidation rates. Sorbed olive oil in plastic was also quantified given that this sorption could induce a swelling of the polymer thus promoting migration.
Amine Kassouf, Maria El Rakwe, Hanna Chebib, Violette Ducruet, Douglas N. Rutledge, Jacqueline Maalouly, Independent components analysis coupled with 3D-front-face fluorescence spectroscopy to study the interaction between plastic food packaging and olive oil, Analytica Chimica Acta, Available online 21 June 2014, ISSN 0003-2670
Ana Isabel Méndez, Elena Falqué, Effect of storage time and container type on the quality of extra-virgin olive oil, Food Control, Volume 18, Issue 5, May 2007, Pages 521-529, ISSN 0956-7135