Polyphenol content of cork granulates at different steps of the manufacturing process of microagglomerated stoppers treated with supercritical CO₂ used for wine bottling

Abstract

The wine closure industry is mainly divided into three categories: screw caps, synthetic closures, and cork-based closures. Among this latter, microagglomerated cork stoppers treated with supercritical CO₂ are now widely used, especially to avoid cork taint contaminations^[1]. They are designed with cork granules obtained from cork offcuts of the punching process during the natural cork stoppers production. A previous study^[2] showed that these stoppers released fewer polyphenols in 12 % (v/v) hydroalcoholic solution than natural cork stoppers. Thus, the present study aims to understand in which step of the manufacturing process of microagglomerated cork stoppers, phenolic compounds are eliminated and which polyphenols are likely to migrate into the wine during horizontal storage. Therefore, granulates from three different steps of the manufacturing process and supercritical CO₂ water extracts were analyzed regarding their polyphenolic compounds. Polyphenol extraction was performed on granulates (1g) using 80 mL of acetone/water (70/30, v/v) acidified at 0.1% HCOOH in order to achieve a total extraction of polyphenols. Granulate extracts were then evaporated until dryness and recovered with 20 mL of 0.1% HCOOH acidified water. Polyphenols of the resulting samples and the supercritical CO₂ water extracts were quantified by HPLC-MS after filtering. The granulates were also extracted with 12% (v/v) ethanol/water to carry out a sensory profile and thus to highlight possible olfactory and/or gustative differences between granulates at the different steps of the manufacturing process.

Acknowledgements: The authors would like to thank Diam Bouchage (Céret, France) for its financial support and for providing samples of granulates and also Christophe Loisel for his expertise in microagglomerated cork manufacturing.

References
1) Taylor, M. K., Young, T. M., Butzke, C. E., & Ebeler, S. E. (2000). Supercritical fluid extraction of 2, 4, 6-trichloroanisole from cork stoppers. Journal of agricultural and food chemistry, 48(6): 2208‑2211, DOI 10.1021/jf991045q
2) Gancel, A.-L., Jourdes, M., Pons, & Teissedre P.-L. (2023). Polyphenol migration from natural and microagglomerated cork stoppers to hydroalcoholic solutions and their sensory impact. Oeno-one (accepted on 3 June 2023).