António M. Jordão

Volatile composition analysis by solid-phase microextraction applied to oak wood used in cooperage (Quercus pyrenaica and Quercus petraea) : effect of botanical species and toasting process

The purpose of this study was to investigate the sorption of selected volatile substances from oak wood-chip samples (Quercus pyrenaica Willd. and Quercus petraea L.) subjected to different toasting levels, namely, without toasting, with medium toasting, and with strong toasting, through the use of solid-phase microextraction (SPME). The main volatile compounds identified as a function of the toasting level and botanical species were furfural, hexanal, α-pinene, d-limonene, decanal, vitispirane, ethyl hexanoate, cis-3-methyl-γ-octalactone (“oak lactone” or “whisky lactone”), α-terpineol, p-xylene, and nonanal. Considering the data obtained from the toasted woods (medium and strong intensity) in comparison with those of nontoasted woods, it can be pointed out that the average peak area and the number of compounds identified in the gas chromatogram decreased during the toasting process. In general, regarding the compounds analyzed, quantitative differences were found between the two oak wood species under study. High values of volatile compounds were found in Quercus pyrenaica oak wood chips. In addition, for the number of compounds identified in oak wood extracts and directly extracted from solid oak wood chips by SPME, it is concluded that the best extraction process for volatile compounds from oak wood is the use of oak wood-chip liquid extracts.

Antioxidant capacity, scavenger activity, and ellagitannins content from commercial oak pieces used in winemaking

In 2005, the European Union authorized the use of oak wood pieces in winemaking, and consequently, the addition of oak chips has been generalized. Thus, the antioxidant capacity, scavenger activity, and ellagitannins content from fourteen different commercial oak wood pieces (Quercus spp.) that can be found on the Portuguese market as alternatives to barrels for aging wines were studied. Commercial oak wood pieces samples from Quercus petraea had significantly higher antioxidant activity values than the pieces from Quercus alba species. In general, antioxidant capacity and scavenging activity decrease with the toasting level of the oak wood pieces samples analyzed. A similar effect was detected in the individual ellagitannin content studied. On the other hand, with the toasting process, the total phenolic content and the ellagic acid concentration increased. Finally, a correlation analysis revealed that ellagitannins contribute to the antioxidant capacity of oak wood pieces studied. From the data presented in this paper, antioxidant capacity and ellagitannin content of the oak wood pieces studied have been clearly related either to the oak wood species used, particle size, or to toasting levels.

Proanthocyanidin content, antioxidant capacity and scavenger activity of Portuguese sparkling wines (Bairrada Appellation of Origin)

BACKGROUND The main object of the present study was to investigate the different proanthocyanidin fraction (monomeric, oligomeric and polymeric fraction) contents, antioxidant capacity and scavenger activity of the most important and representative commercial sparkling wines available in Bairrada Portuguese Appellation of Origin. RESULTS The white commercial sparkling wines tested had much less total phenolic, proanthocyanidin content, antioxidant capacity and scavenger activity than the sparkling red wines. For all white and red sparkling wines the polymeric fraction of proanthocyanidins was the most abundant fraction quantified. The antioxidant capacity was positively correlated with the different proanthocyanidin fractions studied. However, in general, higher correlations between total polyphenols, different proanthocyanidin fractions and antioxidant capacity were found only for red sparkling wines. CONCLUSION The results confirm that Portuguese sparkling wines from Bairrada Appellation of Origin are good sources of antioxidants when compared with other wines elaborated from other grapes varieties and from other regions. At same time, good linear correlations between the levels of each different proanthocyanidin fractions and total polyphenols with antioxidant capacity were found for the commercial sparkling wines analysed.

Ellagitannins from Portuguese oak wood (Quercus pyrenaica Willd.) used in cooperage: influence of geographical origin, coarseness of the grain and toasting level

Abstract The ellagitannins and ellagic acid from extracts of Portuguese oak wood chips (Quercus pyrenaica) used in cooperage from different origins (Gerês and Guarda forests) were analysed by HPLC. The results were compared with the ellagitannin content of wood chips obtained from American (Q. alba) and French (Q. petraea) oak. The influence of heat treatment and the coarseness of the grain on ellagitannins and ellagic acid were also studied. Five ellagitannins (vescalagin, castalagin, roburin D, roburin E and grandinin) and ellagic acid were quantified. Vescalagin and castalagin were the most abundant individual ellagitannins in all of the oak wood chips studied. Portuguese oak wood had the highest content of ellagitannins and ellagic acid, followed by the French and American oaks. The geographical origin of Portuguese oak and the coarseness of the grain of French oak affected the content of ellagitannins and ellagic acid. In general, the ellagitannin content decreased with the toasting process, while the ellagic acid content increased. The toasting process had the highest impact on ellagitannin composition in comparison to the other variables studied.

General phenolic characterisation, individual anthocyanin and antioxidant capacity of matured red wines from two Portuguese Appellations of Origins

BACKGROUND The main aim of this work was to evaluate the general phenolic composition, individual anthocyanin content and total antioxidant capacity from 20 commercial matured red wine samples (vintage from 2005 to 2008) produced in two Appellations of Origin from the north of Portugal: Douro and Dão. RESULTS The results showed that the levels of general phenolic compounds, individual anthocyanins and antioxidant capacity in the 20 matured red wine samples analysed differed significantly. In addition, matured red wine samples aged in oak wood had a lower total individual anthocyanin content (from 13.85 to 56.79 mg L(-1), averaging 46.13 mg L(-1)) than wines aged in bottle (from 25.93 to 252.82 mg L(-1), averaging 94.17 mg L(-1)). The total antioxidant capacity values of the analysed wines showed quantitative differences among the values obtained from each antioxidant method applied as well as differences in the range of variation, especially for the values obtained by the DPPH method. CONCLUSION The wines used in this study constitute quite a heterogeneous group, made from different Portuguese red grape varieties, with diverse ages and two ageing processes (bottle and oak wood barrels); and accordingly, they showed important differences, especially in their phenolic composition. Finally, the oak wood ageing process before bottling had a negative effect in individual anthocyanins content in contrast to matured red wines submitted only to a bottle ageing process.

Relationship Between Antioxidant Capacity, Proanthocyanidin and Anthocyanin Content During Grape Maturation of Touriga Nacional and Tinta Roriz Grape Varieties

To investigate antioxidant capacity in seeds and skins during grape maturation and its relationship with anthocyanin and proanthocyanidin content, two Portuguese red grape varieties, Touriga Nacional and Tinta Roriz (Vitis vinifera L.) were studied. Two analytical methods were used for antioxidant capacity analysis: the DPPH and ABTS methods. Proanthocyanidins from seeds and skins were separated into monomers, oligomers and polymers, while 13 individual anthocyanins from the skins were also evaluated by HPLC. For both grape varieties studied, antioxidant capacity from the skins and seeds was characterised during grape maturation by a general decrease, mainly in the first weeks after veraison, followed by stabilisation and a slight increase in the values in the last three weeks of ripening. A similar tendency was observed for the amount of all the different proanthocyanidin fractions quantified. Our results also showed that seeds are an important source of proanthocyanidins with respect to the grape berry skins. Seeds were also the grape berry fraction with the highest antioxidant capacity when compared to the antioxidant capacity content of the skins. For the 13 individual monomeric anthocyanins quantified during grape maturation, evolution was generally characterised by a continuous increase in the values. However, for some of the individual anthocyanins, the continuous increase was followed by stabilisation or a decrease in the values in the last weeks of ripening. Finally, there was a positive relationship between the different proanthocyanidin fractions and antioxidant capacity of both grape varieties studied; while a negative relationship during grape maturation was obtained for individual anthocyanins.

Extraction of Some Ellagic Tannins and Ellagic Acid from Oak: Wood Chips (Quercus pyrenaica L.) in Model Wine Solutions: Effect of Time, pH, Temperature and Alcoholic Content

The subject of the present work is the study of the influence of pH, temperature, alcoholic content and time on the extraction of some individual ellagic tannins (castalagin, vescalagin, grandinin, roburin D and E) and ellagic acid from oak wood chips (Quercus pyrenaica L.) within model wine solutions. The determination of these compounds by reversed-phase high-performance liquid chromatography (HPLC), after 104 extraction days, enabled us to establish the qualitative and quantitative evolution of each component and the effect of each extraction condition on individual and total ellagic tannins from oak wood chips. Vescalagin and castalagin were the most abundant individual ellagic tannins measured under all extraction conditions. Individual ellagic tannins and ellagic acid increased during the first weeks of extraction, followed by a decrease. Under the extraction conditions examined, temperature was the main factor influencing ellagic tannins and elagic acid evolution. The results suggest that a decrease/degradation of these compounds is less noticeable at low temperatures (12oC). After 104 extraction days the ellagic tannins content in a model wine solution at 12oC was higher than the content of ellagic tannins in solutions at 20oC. On the other hand, the effects of alcoholic content and pH of model wine solutions on the extraction and evolution of the analysed compounds (except for castalagin and vescalagin) seemed to be less important than temperature.

Evaluation of Textural Properties in Apples of Regional Varieties

Regional varieties of apples present an endogenous patrimony that should be preserved and promoted to guarantee biodiversity of genetic resources. In the present work, Texture Profile Analysis (TPA) was performed to apples of fourteen different regional varieties, having in consideration the spatial geometry of the fruits, and the textural parameters: hardness, adhesiveness, springiness, cohesiveness, and chewiness were assessed. The samples to perform the TPAs were obtained from different locations in the fruit–external and internal–and considering axial and radial orientations. The results of these analysis performed allowed us to conclude that the apples from regional varieties showed different textural properties among themselves. Furthermore, it was generally observed that hardness does not vary much according to the internal or external location of the sample, but varies quite significantly according to the orientation, being generally higher for the axial measurements. From the present work, it was possible to conclude that, in terms of textural properties, the varieties studied showed important differences.

Antioxidant capacity, radical scavenger activity, lipid oxidation protection analysis and antimicrobial activity of red grape extracts from different varieties cultivated in Portugal

The aim of this study was to investigate the antioxidant capacity, radical scavenger activity, lipid oxidation protection and antimicrobial activity of grape extracts from 12 different red grape varieties cultivated in Portugal. The mean values of total phenolic content quantified in grape extracts varied from 833.7 to 2005.6 mg/L gallic acid. Antioxidant capacity results showed different values for each grape variety ranging from 3.96 to 32.96 mm/L Fe(II). The scavenger activity values ranged from 15.99% to 54.82% for the superoxide radical and from 11.79% to 29.67% for the hydroxyl radical. The grape extracts with the highest antioxidant capacity had a positive effect on the lipid oxidation protection and induced low peroxide values in butter samples. Finally, concerning antimicrobial activity, grape extracts from Touriga Nacional and Tinta Roriz grape varieties had significant antimicrobial activity, especially notable for total mesophilic aerobics.

Composition of regional Portuguese apple cultivars in different harvest years.

In the present study, apples of regional cultivars originating from Portugal were compared in terms of some chemical properties during three consecutive harvest years. It was possible to conclude that these regional cultivars of apples were generally sweeter and contained more minerals than other cultivars described in the literature. The data revealed that the acid, protein, and mineral content depended on the apple cultivar. The acid content varied notably with the 2004, 2005, and 2006 harvests. For total sugar or protein content, the variations observed were comparatively smaller. In the 2004 and 2005 harvests, the sugar and protein contents were similar but differ from the 2006 harvest. In respect to mineral content, the 2004 harvest registered the highest differences, and this was also the year when the apples had the highest maturation index, calculated as the sugar/acid ratio.