Sealing effectiveness of different types of closures towards volatile phenols and haloanisoles

Aim: To determine if aerial contamination can induce the migration of volatile compounds through wine closures after bottling. Methods and results: Bottled white wines sealed with cork stoppers (natural and microagglomerate), synthetic closures and screw caps were stored under an environment contaminated with three deuterium-labeled compounds : (d5)-2,4,6-trichloroanisole (d5-TCA), (d4)-4-ethylphenol (d4-E4P) and (d5)-4-ethylguaiacol (d5-E4G). Wines, closure sections (outer, middle and inner) and screw cap liner were assessed over time for the concentration of different compounds by solid phase microextraction-gas chromatography-mass spectrometry (SPME-GC-MS). The results collected during 30 months of storage showed that large amounts of all compounds were essentially retained in the outer portion of cylindrical closures, both cork and synthetic. However, these compounds were able to penetrate through synthetics and screw caps and contaminate the wine. Conclusion: Cork stoppers have proven to be an effective barrier to the migration of aerial volatile compounds such as d5-TCA, d4-E4P and d5-E4G, whereas permeable closures such as synthetic and screwcap saranex did allow the migration of those compounds into bottled wines. Significance and impact of the study: This study provides practical information about the sealing properties of different closures for a sound decision-making with regard to packaging. To the best of our knowledge, this is the first report of post-bottling aerial contamination via migration of volatile compounds through wine closures