Metabolic response to elevated CO2 levels in Pinus pinaster Aiton needles in an ontogenetic and genotypic-dependent way.

Global climate changes involve elevated atmospheric [CO2], fostering the carbon allocation to tree sink tissues, partitioning it into metabolic pathways. We use metabolomics analysis in adult and juvenile needles of four Pinus pinaster genotypes exposed to two levels of growth [CO2]: ambient (400 µmol mol-1) and enriched (800 µmol mol-1), to know if the metabolic responses are genotype-dependent and vary according to the stage of needle ontogeny. The eCO2-induced changes in the needle metabolomes are more significant in secondary metabolism pathways and especially meaningful in juvenile needles. The heteroblasty has important consequences in the expression of the metabolome, and on the plasticity to CO2, determining the level of specific metabolite accumulation, showing an interdependence between adult and juvenile needles. The P. pinaster needle metabolomes also show clear quantitative differences linked to genotype, as well as regarding the metabolic response to eCO2, showing both, common and genotype-specific biochemical responses. Thus, the changes in flavonol levels are mainly genotype-independent, while those in terpenoid and free fatty acids are mainly genotype-dependent, ratifying the importance of genotype to determine the metabolic response to eCO2. To understand the adaptation mechanisms that tree species can develop to cope with eCO2 it is necessary to know the genetically distinct responses within a species to recognize the CO2-induced changes from the divergent approaches, what can facilitate knowing also the possible interrelation of the physiological and metabolic responses. That could explain the controversial effects of eCO2 on the carbon-based metabolite in conifers, at the inter- and intra-specific level.

LC-DAD/ESI-MS/MS study of phenolic compounds in ash (Fraxinus excelsior L. and F. americana L.) heartwood. Effect of toasting intensity at cooperage.

The phenolic composition of heartwood extracts from Fraxinus excelsior L. and F. americana L., both before and after toasting in cooperage, was studied using LC-DAD/ESI-MS/MS. Low-molecular weight (LMW) phenolic compounds, secoiridoids, phenylethanoid glycosides, dilignols and oligolignols compounds were detected, and 48 were identified, or tentatively characterized, on the basis of their retention time, UV/Vis and MS spectra, and MS fragmentation patterns. Some LMW phenolic compounds like protocatechuic acid and aldehyde, hydroxytyrosol and tyrosol, were unlike to those for oak wood, while ellagic and gallic acid were not found. The toasting of wood resulted in a progressive increase in lignin degradation products with regard to toasting intensity. The levels of some of these compounds in medium-toasted ash woods were much higher than those normally detected in toasted oak, highlighting vanillin levels, thus a more pronounced vanilla character can be expected when using toasted ash wood in the aging wines. Moreover, in seasoned wood, we found a great variety of phenolic compounds which had not been found in oak wood, especially oleuropein, ligstroside and olivil, along with verbascoside and isoverbascoside in F. excelsior, and oleoside in F. americana. Toasting mainly provoked their degradation, thus in medium-toasted wood, only four of them were detected. This resulted in a minor differentiation between toasted ash and oak woods. The absence of tannins in ash wood, which are very important in oak wood, is another peculiar characteristic that should be taken into account when considering its use in cooperage.

Volatile compounds in acacia, chestnut, cherry, ash, and oak woods, with a view to their use in cooperage.

Extracts of wood from acacia, European ash, American ash, chestnut, cherry, and three oak species (Quercus pyrenaica, Quercus alba and Quercus petraea) before and after toasting in cooperage were studied by GC-MS. 110 compounds were detected, and 97 of them were identified. In general, all studied woods showed more lignin derivatives than lipid and carbohydrate derivatives, with a higher variety of compounds detected and abundance of them. The toasting led to an increase in the concentrations of most of these compounds, and this increase is especially important in acacia, chestnut and ash woods. The cis and trans isomers of beta-methyl-gamma-octalactone and isobutyrovanillone were only detected in oak wood, 3,4-dimethoxyphenol and 2,4-dihydroxybenzaldehyde only in acacia wood, and p-anisaldehyde and benzylsalicylate only in cherry wood, before and after toasting, and these compounds could be considered chemical markers for each one of these woods. Moreover, each wood has a characteristic volatile composition, from a quantitative point of view, and therefore we can expect a characteristic sensorial profile. The oak wood turned out to be the most balanced, since although it provides a lot of volatile compounds to the aroma and flavor of aged wine, it can do so without masking their primary and secondary aroma. On the whole, toasted acacia and chestnut woods showed a very high richness of studied compounds, as lignin as lipid and carbohydrate derivatives, while cherry and ash were much richer than toasted oak wood in lignin derivatives, but much poorer in lipid and carbohydrate derivatives.

Volatile compounds in a spanish red wine aged in barrels made of Spanish, French, and American oak wood.

A red Rioja wine was aged in barrels made of Spanish oak wood (Quercus robur, Quercus petraea,Quercus pyrenaica, and Quercus faginea) during 21 months. The concentrations of some volatile compounds [syringaldehyde, vanillin, eugenol, maltol, guaiacol, 4-ethylphenol, cis and trans isomers of beta-methyl-gamma-octalactone, 2-furfuraldehyde, 5-methyl-2-furfuraldehyde, 5-(hydroxymethyl)-2-furfuraldehyde, and furfuryl alcohol] were studied in these wines and compared with those of the same wine aged in barrels made from French oak of Q. robur (Limousin, France) and Q. petraea (Allier, France) and American oak of Quercus alba (Missouri). Similar concentrations of these compounds were found in wines aged in Spanish and French oak wood barrels, and significantly different concentrations were found with respect to wines aged in barrels made of American oak wood, indicating a different behavior. Thus, wines with different characteristics were obtained, depending on the kind of wood. Also, the kind of wood had an important influence on sensory characteristics of wine during the aging process. Spanish oak wood from Q. robur, Q. petraea, and Q. pyrenaica can be considered to be suitable for barrel production for quality wines, because a wine aged in barrels made of these Spanish oak woods showed similar and intermediate characteristics to those of the same wine aged in French and American oak woods usually used in cooperage.