abstract
The monomeric composition of suberin extracts obtained by gradual alkaline methanolysis of Quercus suber cork was determined by gas chromatography-mass spectrometry (GC-MS). Results show that l-alkanols and alkanoic and a,omega-alkanedioic acids are preferentially removed upon mild alkaline conditions, whereas mid-chain-modified omega-hydroxyalkanoic acids are preferentially removed under stronger alkaline conditions. Saturated w-hydroxyalkanoic acids are found to be abundant in all suberin extracts. These results are consistent with two distinct suberin fractions with different locations in cork cell walls and/or esterification degrees. It is proposed that these fractions correlate with the two main suberin peaks in the solid state C-13 NMR spectra of cork and suberin extracts. Quantitative CC-MS analysis showed that suberin monomers comprise similar to 30% (w/w) of the suberin extracts, the remaining comprising nonvolatile structures with high M-n, values, as measured by vapor pressure osmometry. The presence of a large fraction of high molecular weight aliphatic structures in suberin extracts is supported by the corresponding NMR spectra.
keywords
CHEMICAL CHARACTERIZATION; POLYESTER; PLANTS
subject category
Agriculture; Chemistry; Food Science & Technology
authors
Lopes, MH; Gil, AM; Silvestre, AJD; Neto, CP
our authors
Ana Maria Pissarra Coelho Gil
Associate Professor with Aggregation
Armando Jorge Domingues Silvestre
Full professor