In an article published online on July 14, 2021, in the peer-reviewed journal Chemistry, Paula Vera and colleagues from the Analytical Chemistry Department, University of Zaragoza, Spain, reported on the identification of non-volatile and volatile compounds migrating from wine corks using an untargeted approach.
The authors performed migration experiments with eight corks made of ethylene-vinyl acetate (EVA) supplied by European companies using 3% acetic acid and 20% ethanol as simulants for non-alcoholic and alcoholic beverages. After an incubation period of 10 days at 60 °C, the samples were analyzed for volatile compounds with gas chromatography-mass spectrometry (GC-MS) and for non-volatile compounds with ultrahigh performance liquid chromatography (UHPLC) coupled to an ion-mobility separation quadrupole-time of flight mass spectrometer (UHPLC-IMS-QTOF). By using an in-house spectral library, the researchers could isolate the unique markers migrating from the samples, and the “ion mobility incorporated into the QTOF mass analyzer provided clean spectra and improved resolution, thus reducing the number of possible interferences.” To confirm identification, analytical standards of candidate compounds were applied to chemical analysis and used for the comparison with samples.
In total, Vera and colleagues identified seven volatile and 43 non-volatile compounds in the samples, including nine additives such as the antioxidants butyl 4-hydroxybenzoate (CAS 94-26-8), Irganox 1010 (CAS 6683-19-8), Irganox 1076 (CAS 2082-79-3), Irgafos 168 (CAS 31570-04-4), butylated hydroxytoluen (BHT, CAS 128-37-0), a cross-linking agent, and the lubricants N,N’-ethylenebisoleamide (EBO, CAS 110-31-6) and octadecanamide, N,N’-1,2-ethanediylbis- (CAS 123-26-2). BHT is also listed in the Food Packaging Forum’s Food Contact Chemicals database (FCCdb) as a priority hazardous substance. The majority of migrating chemicals (84%) were non-intentionally added substances (NIAS). These included several cyclic co-oligomers of different chain sequences resulting from the copolymerization of monomers, as well as oxidation and break-down products. All chemicals had a higher migration potential in 20% ethanol, simulating alcoholic beverages, than in 3% acetic acid.
The scientists also evaluated whether the level of migrating chemicals complied with current legislation. They found that one cork leached three compounds “to 20% ethanol at a concentration in excess of the level permitted by their Cramer classification. This implies that one of the tested corks is not suitable as food contact material.” With their study, the authors aim to elucidate the nature and potential origin of chemicals which can help producers “to reduce the prevalence of these compounds in the formulation of the final product.”
Vera, P. et al. (2021). “The migration of NIAS from ethylene-vinyl acetate corks and their identification using gas chromatography mass spectrometry and liquid chromatography ion mobility quadrupole time-of-flight mass spectrometry.” Food chemistry. DOI: 10.1016/j.foodchem.2021.130592