GC−MS Study of Volatiles of Normal and Microbiologically Attacked Cork fromQuercus suberL.

Abstract

The volatile compounds of cork were studied by gas chromatography and combined gas chromatography−high-resolution mass spectrometry using simultaneous distillation−extraction to prepare the samples. To assess the origin of the volatiles, three different types of samples were analyzed: “normal”, attacked by Armillaria mellea, and infested by molds. The study of the volatiles of these different types of corks allowed the identification of the chemical modifications which may occur in cork polymers. The cork attacked by A. mellea showed higher amounts of phenols, vanillin, benzaldehyde, benzyl alcohol, and chlorinated compounds than normal cork; this may indicate lignin degradation. The cork infested by molds contained higher levels of 3-methyl-1-butanol, 1-octen-3-ol, 1-octanol, 2-methylisoborneol, chlorinated compounds, and methyl ketones. These components resulting from microbial metabolism were also present in cork attacked by A. mellea. The use of cork attacked by A. mellea is not recommended in the manufacture of cork stoppers, since these types of cork have volatile compounds likely to cause off-flavors in wine. For the same reason it is important to reduce the likelihood of mold development during the standing period. Keywords: “Normal” cork; Armillaria mellea; molds; volatile components; musty and moldy odors

Volatiles from submerged and surface‐cultured beefsteak fungus, Fistulina hepatica

“…14,26,28 The amounts of D-fenchol in cork slabs obviously increased upon the attack of the cork by a saprophytic basidiomycete Armillaria mellea. 29 D-Fenchol was also detected in the fruiting bodies of the wild basidiomycete Cystoderma carcharias, 22 and (E)-nerolidol occurred in the fruiting bodies of the same species. 6 The diterpene biformene was first isolated and identified from Dacrydium biforme and was later also detected in essential oils of plant leaves.…”

Antennal response of Prinobius myardi to synthetic tree volatiles

“…Plant volatiles are also probably involved in the recognition of weakened, damaged hosts (Allison et al 2004;Hanks et al 2012). Moderate EAG responses were elicited in P. myardi by three compounds associated with emissions from wounded leaves of Quercus species: the known ubiquitous GLV (E)-2-hexenal, two acyclic monoterpenes, β-myrcene and (E)-β-ocimene (Paris et al 2011;Pearse et al 2013), and 3-methyl-butanol (found in microbially colonized cork from Q. suber (Rocha et al 1996)). …”

“…The main group included 16 analogues of volatiles identified in foliar emissions from Q. suber and Q. ilex: the monoterpenes, β-pinene, (+)-α-pinene, (+)-limonene, β-myrcene, 1,8-cineole, (E)-β-ocimene, α-terpinene, γ-terpinene, α-phellandrene, ρ-cymene and α-terpineol (Sánchez-Osorio et al 2008;Llusià et al 2012); the GLVs, (E)-2-hexenal, (Z)-3-hexenol and (Z)-3-hexenyl acetate (Fürstenau et al 2012); and the triterpenes, lupenone and erithrodiol (Monaco and Previtera 1984). We also tested several analogues of compounds found in Q. suber cork, namely gallic and ellagic acids, the triterpene friedelin and 3-methyl-butanol (Rocha et al 1996). Turpentine oil was used as the standard stimulus (Sánchez-Osorio et al 2007).…”

Simultaneous headspace solid phase microextraction analysis of off‐flavour compounds from Quercus suber L. cork

“…As may be seen from The results clearly demonstrate that the HS-SPME analysis of this group of compounds may be affected by variation of the 1OCT concentration. As 1OCT is a chemical component of both wine and cork, 11,37,38 in concentrations ranging between 3 and 250 µg L −1 , these results may explain the reported discrepancies between the sensory analysis of a compound and its quantification by HS-SPME. Two possibilities may be noted: (i) the detection of a given aroma by sensory analysis is not confirmed by the HS-SPME analytical results and/or (ii) the HS-SPME analytical results are higher than the SPL but no positive sensory detection was made.…”

“…In order to cover the range of concentrations of 1OCT that may be detected in cork and/or wine, 11,37,38 four factors of multiplication of the concentration of 1OCT in relation to its concentration in the reference solution (78.0 µg L −1 ) were established: 0.3, 0.5, 2.0 and 2.7. The ratios A x /A 0 , with A x the chromatographic area of the given compound in the solution where the 1OCT concentration was varied and A 0 the chromatographic area of the same compound in the reference solution, are shown in Table 5.…”