Novel Sustainable Alternatives for the Study of the Chemical Composition of Cork

Abstract

Cork is a natural and renewable material extracted from the cork oak Quercus suber L. (1) Background: The cellular structure and chemical composition of the plant wall give cork its physical and mechanical properties. Chemically, the composition of cork is principally dominated by the presence of suberin as the main structural cell wall component and affected by its close association with other components. The usual chemical analysis of cork has been partially adapted from wood and other lignocellulosic analytical methods and it is a method with extensive procedures. This study aims to (i) find quicker and more sustainable methods for testing the cork chemical composition, (ii) conduct extraction tests using alternative techniques, (iii) optimize alternative methodologies, and (iv) validate the proposed sustainable methodologies. (2) Methods: Microwave-assisted extraction (MAE) and accelerated solvent extraction (ASE) are explored as alternative systems to the traditional method. The percentages of the extractives obtained via MAE are lower than the percentages obtained by means of the classical composition. (3) Results: However, the percentages of suberin are very similar in both methods: 46.39% in the case of the classical composition and 45.11% in the case of microwave-assisted extraction. No significant differences are observed between the content of the extractives in the dichloromethane, ethanol, and water obtained via ASE and the results obtained with the classical methodology. (4) Conclusions: MAE and ASE are faster methods; they use less solvents and provide more reproducible results than the classical chemical composition methodology. These data pave the way for novel sustainable alternatives relative to the studies of the chemical composition of cork.