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영어

Cork is an impermeable material, the phellem layer of bark tissue that is harvested for commercial use primarily from Quercus suber (the cork oak), which is native to southwest Europe and northwest Africa. Cork is mainly composed of suberin, a hydrophobic substance. Because of its impermeable, buoyant, elastic, and fire retardant properties, it is used in a variety of products such as wine stoppers, panels, boards and paving materials. Cork production is generally considered eco-friendly and sustainable because the cork tree is not cut down to obtain cork; only the bark is stripped to harvest the cork. The tree continues to live and grow. The sustainability of production and the easy recycling of cork products and by-products are two of its most distinctive aspects. In our previous studies, corks in Quercus variablis (in South Korea) and Quercus suber (in Portucal) were analyzed to compare the chemical compositions and its natural durability. Both species had similar composition of chemical components. In particular, the contents of suberin in the species were shown as 47.6% and 50.2%, respectively. As a result of fungal decay resistance test, there was no big difference in weight losses and morphological changes of both species. Based on the results, it was thought that the cork of Q. variabilis could be fully utilized as an alternative resource for that of Q. suber. As a main substance in corks, suberin is a complex polymer composed of two domains, polyaliphatic and polyphenolic, and thus it has great potential to be used for various purposes. The monomers, di-acids and phenolic acids have several applications in food, polymer and pharmaceutical industries. For examples, phenolic acid monomer of suberin is a secondary metabolite. Extraction of antioxidants from natural sources can replace synthetic antioxidants that do not have toxic and carcinogenic property. In polymer industries, suberin monomers are used as macromolecular materials either as additives or inactive starting monomeric form. Recent studies have explored the polyester nature of the suberin monomer to synthesize various polyester polymeric materials. Therefore, the isolation of suberin monomers or low-molecular weight compounds from renewable sources is the topic of focus nowadays. Hence, waste from corks rich in suberin components could be a promising source for these renewable chemicals extraction.