Waxes composition of reproduction cork from Quercus suber and its variability throughout the industrial processing

The chemical composition of waxes was studied in cork planks from three dif ferent trees of Spanish Quercus suber at four different stages of the indus trial processing of the first transformation: stripping, first rest, boilin g followed by open air rest and boiling followed by store-room rest. Waxes were extracted with chloroform (CHCl3) and the extract was submitted to sap onification in order to obtain the neutral and acid fractions. The trimethy lsilyl derivatives of both fractions were analysed by GC-MS. An important d ecrease of the total content of waxes -CHCl3 extract-(average values: 10.13 to 4.91%) and of the acid fraction (average values: 2.51 to 0.96%) was obs erved throughout the industrial processing. Some differences were also foun d among trees, two of them being richer in total waxes (average, 8.14 and 7 .71%) than the other one (average, 4.67%). Concerning the three groups of i dentified components (fatty acids, fatty alcohols and triterpenes), the con tents of the fatty alcohols and acids suffer an important reduction during the first rest (average values: 30.39 to 17.53% and 58.73 to 31.48%, respec tively), while after boiling, there is a decrease of the triterpenes concen trations (79.16 to 58.00% -neutral fraction- acid 40.23 to 23.20% -acid fra ction-), being greater when the second rest is carried out in a store room. Significant differences among trees were only found in the fatty alcohols contents. The neutral fraction was mainly composed by fatty alcohols tall t he even members from C-18 to C-26, With traces of intermediate odd members and some unsaturated groups, C-20 and C-21) and triterpenes (14 components, among them friedelin, betulin and cerin were identified), and a very small amount of monocarboxylic fatty acids (C-16, C-18, C-22 and C-24 members) w as also present. The main group of components of the acid fraction was that of fatty acids (saturated even C-12-C-24 and odd C-15, C-17, C-21 members, accompanied by a great amount of unsaturated terms and some omega-hydroxya cids, 18-hydroxy-9,12-octadecadienoic and 18-hydroxy-9-octadecenoic acids). Four triterpenes, the C-20, C-24 and C-28 alcohols and ferulic acid were a lso detected in the acid fraction. Some of these individual components of e ach fraction were also affected by the industrial processing and presented significant differences among the studied trees.