CHEMICAL CHARACTERIZATION OF REPRODUCTION CORK FROM SPANISH QUERCUS-SUBER

The chemical composition of Quercus, suber reproduction cork was studi ed in planks from three different trees at different stages of their i ndustrial processing and in samples collected in seven locations in th e three main Spanish production areas. Extracts in chloroform, methano l and water, neutral and acid fractions of waxes, suberin, lignin, hol ocellulose and pentosans, and polyphenols (low molecular weight polyph enols and tannins), were quantified. Suberin was the main component in all the samples, followed by lignin and holocellulose in lower concen trations. The most affected variables throughout the industrial proces sing were: lignin, chloroform and water extracts and the acid fraction of waxes. These variables did not allow one to distinguish the studie d trees, which are differentiated by the percentages of methanol extra cts, the tannic fraction of polyphenols, the free of suberin residue a nd the holocellulose content. Four variables were selected as those wh ich provided the greatest discrimination among provenances: methanol e xtract, low molecular weight polyphenols, desuberinized residue and ac id fraction of waxes. However, the studied populations can not be clea rly distinguished by their chemical composition and no relationship wa s found between geographical proximity of their provenances and chemic al resemblance.