Procyanidin composition of Chardonnay, Mauzac and Grenache blanc grapes

Dimer procyanidins, galloylated or not, and trimers were analysed in three white grape varieties: Chardonnay, Mauzac and Grenache blanc. Procyanidins were extracted from the different components of the grape cluster (seeds, stems, skins and pulps) and then quantified by HPLC. Procyanidin B1 is the major component in stems and skins while procyanidin B2 is the major component in seeds

Novel memory-based sensory approach to assess large-scale typicality: the case of mainland Portugal red wines

Twenty professional wine experts were asked to describe their prototypical construct of a representative young red wine from each of the 12 Protected Geographical Indications (PGI) of mainland Portugal. No samples were assessed; the experiment was based on memory alone by completion of 12 extended self-reported sensory questionnaires. Four large-scale areas were differentiated, the typicality being statistically validated and described from a sensory standpoint. Alcohol, acidity, bitterness, and astringency were cross-linked; the respective variations were correlated with published literature and expressed as key factors for the regional macroscale area differentiation. Bitterness and astringency were found to be sensory different and related on a geographical scale, as bitterness was primarily affected by inland/coastal influence; while astringency confirmed its customary north/south dependence that finding is to be considered a new understanding. Moreover, with the proposed methodology, it was possible to achieve a novel nationwide sensory characterization of PGIs, overcoming present day limitations on macroscale sensory research and sample representativeness. Results by uncalibrated prototypical memory assessment of single PGI Beira Atlântico were compared with the outcome of calibrated wine sampling assessment by local experts, using the same sensory questionnaire, and were found significantly correlated. The need for a calibration stage was found uneven regarding the overall group of scrutinized wine descriptors

Dimer and trimer procyanidins in Carignan and Mourvèdre grapes and red wines

Dimer procyanidins, galloylated or not, and trimers were analysed in the red grapes Carignan and Mourvedre. Procyanidins were extracted from the various parts of the grape bunch and then quantified by HPLC. In Carignan and Mourvedre grapes, procyanidin B2 was the major component in seeds, whereas procyanidin B1 was the major component in stems and skins. Trimeric procyanidins were also present in grapes in larger amounts. Various red wines were produced from Carignan and Mourvedre grapes, using different winemaking procedures: entire crushed harvest, destemmed harvest, carbonic maceration and heating of the harvest. Entire crushed harvest gave red wines with the highest levels of procyanidins. An important release of procyanidins, especially procyanidin B1 from skins and stems, when present, occurred.Procyanidines dimères et trimères des raisins et vins rouges de Carignan et MourvèdreDes procyanidines dimères galloylées et non-galloylées, et trimères sont dosées dans deux cépages rouges: Carignan et Mourvèdre. Les procyanidines sont extraites des différentes parties de la grappe puis quantifiées par CLHP en phase inverse. Dans le raisin de Carignan et de Mourvedre, la procyanidine B2 est la plus abondante dans les pepins, tandis que la procyanidine B1 est la plus abondante dans les rafles et pellicules. Les procyanidines trimères sont aussi présentes en quantités importantes. Différents vins rouges ont été élabores à partir des cépages Carignan et Mourvèdre, en utilisant plusieurs téchniques de vinification: vendange foulée; vendange éraflée, macération carbonique et le chauffage de la vendange. Les quantités les plus abondantes de procyanidines sont obtenues dans des vins issus d'une vendange entière et foulée

Research Note: Effect of Light Quality on Fruit Growth, Composition and the Sensory Impact of the Wines

The stage at which grapes are harvested has an influence on the aromatic and phenolic composition of the berries and the resulting wines. The aim of this study was to evaluate wines harvested sequentially as outlined in the berry sugar accumulation model. Two vintages and treatments in which the light qualityand quantity were altered at the fruit zone were compared. In 2010/2011, the grapes were harvested at two ripening stages after the sugar loading plateau was reached, namely the “fresh fruit” stage (20-25 days afterwards) and “pre-mature” stage (at approximately 35 days). In the 2011/2012 season, grapes were harvested 45 days after the sugar loading plateau was reached (the “mature fruit” stage). Vegetative aromas were synonymous with the “fresh fruit” stage in 2010/2011, while the 2011/2012 wines from the “mature fruit” harvest date were characterized by raisin, prune and spicy aromas. In both seasons, the control treatments were rated more intense in ‘satin in the mouth’ in and after expectoration. Wines in which the UV-B radiation was excluded during berry growth were rated the highest in the mouthfeel attribute ‘coarseness’ in both treatment seasons. Wines were analyzed chemically for phenolic content using HPLC, and sensorial using descriptive analysis with a trained panel. In the leaf removal treatments,higher acidity content enhanced the perception of astringency in the wine. Wines were analyzed chemically for phenolic content using HPLC and sensorial using descriptive analysis with a trained panel. Overall, the data showed that grape composition was altered by varying light quality, within a season, but seasonalvariation overrode treatment effects. Flavonol concentration in 2011/2012 wine was higher in the exposed leaf removal treatment compared to the other treatments. High light intensities in 2011/2012 season increased anthocyanin concentration in the wine.. This study emphasizes the importance of the quality and quantity of light on the composition and quality of wines, and presents new findings regarding sensory attributes associated with harvesting at different ripening stages.

Blends of wood chips from oak and cherry: impact on the general phenolic parameters and sensory profile of a white wine during the aging process

Today, there is a restricted knowledge about the potential impact of the use of different wood chip species on the white wine aging process. This lack of knowledge is even greater when wood species are used in blends of different species. Thus, the aim was to carry out a comparative analysis of the impact of different blends of wood chip species, involving oak and cherry wood, on different phenolic and color parameters, browning potential index and sensory profile of a white wine during the aging process. During the aging time studied, the use of wood chips induced an increase of wine phenolic content and color intensity, particularly in wines aged in contact with cherry wood chips alone or in blends with oak wood chips. A similar tendency was also detected for browning potential index. Regarding the sensorial results, the use of different wood chip species has an impact on the increase of "woody aroma" for the wines aged with oak wood chip species and also an increase of "body" and "astringency" descriptors for the wines aged with oak chips alone or blended with cherry chips. This work advances our understanding of the impact of different wood chip species separately or by the use of blends on white wine quality

Grape flavonoid evolution and composition under altered light and temperature conditions in Cabernet Sauvignon (Vitis vinifera L.)

Original ResearchThe evolution of flavonoids under altered temperature and light conditions in the fruit zone was followed in Cabernet Sauvignon (Vitis vinifera L.) grapes during ripening. The study was conducted over two consecutive seasons in 2010/2011 and 2011/2012 comprising two main treatments in which the light quantity was manipulated in the bunch zone: (1) standard (STD) with no lateral shoot or leaf removal and (2) leaf removal west (LRW) treatment with leaf removal on the western side of the bunch zone. Furthermore, the light quality was altered by installing ultraviolet B-suppression sheets within the bunch zone in both seasons. Tannin evolution was dependent on the prevailing light quality/ quantity and temperatures during berry development in a particular season. Grape seed tannin accumulation coincided with seed development and commenced at the early stages of berry development. Seed proanthocyanidin composition was not influenced by the treatments. The largest impact on proanthocyanidin accumulation and structure in the skin was due to seasonal variations highlighting the complex interaction between light quality and/or quantity across the two growing seasons and eventually the complex interaction with temperature. Flavonol accumulation was significantly influenced by the light quality, which is known to be the main abiotic driver of flavonol biosynthesis regulation. Anthocyanin concentration and content were largely dependent on the temperature and light quality in a particular season. Anthocyanin composition was altered by the season rather than the treatmentinfo:eu-repo/semantics/publishedVersio

Effect of solvent-dependent viscoelastic properties of chitosan membranes on the permeation of 2-phenylethanol

The viscoelastic behaviour of chitosan was followed by dynamic mechanical analysis (DMA) while the sample was immersed in gradient compositions of water/ethanol mixtures. The swelling equilibrium of chitosan membranes, both crosslinked with genipin or not, increased linearly with the water content. Increasing the water content, it was simultaneously observed a peak in the loss factor (around 25 vol.%) and a reduction of the storage modulus, which was attributed to the a-relaxation of chitosan. This was the first time that the glass transition dynamics in a polymer was monitored in immersion conditions where the composition of the plasticizer in the bath is changed in a controlled way. The water content at which tan d presented a maximum increased with both increasing frequency and increasing crosslinking density. The permeability decreased steadily with the ethanol content, reaching very low values around the glass transition. Therefore we hypothesize that conformational mobility of the polymeric chains may play an important role in the diffusion properties of molecules trough polymeric matrices.This work was partially supported by the Portuguese Foundation for Science and Technology (FCT), through funds from the POCTI and/or FEDER programmes and through the scholarship SFRH/BPD/34545/2007 granted to Ricardo M.P. da Silva. This work was carried out under the scope of the European NoE EXPERTISSUES (NMP3-CT-2004-500283) and also partially supported by the EU funded projects HIPPOCRATES (STREP - NMP3-CT-2003-505758) and PROTEUS (INTERREG III A - SP1.P151/03). The technical assistance of Ana Pinheiro in the execution of the DMA experiments is also acknowledged

Metal reduction in wine using PVI-PVP copolymer and its effects on chemical and sensory characters

We studied the influence of an adsorbent PVI-PVP resin (a copolymer of vinylimidazole and vinylpyrrolidone), on the removal of heavy metals in wines, mainly copper (Cu), iron (Fe), lead (Pb), cadmium (Cd) and aluminium (Al). The study also investigated the influence of PVI-PVP on the physical-chemical and sensory characteristics of white and red wines, comparing its effect when applied in the must and in the wine. The removal of metals was more effective when PVI-PVP was applied to the wine than to the must. The removal of Fe and Pb was more effective in white wines than in red wines, while the removal of Cu and Al was higher in red wines. In general, the higher the PVI-PVP dose, the greater the quantity of metallic elements (copper, iron, lead and aluminium) that are removed. PVI-PVP had a minor effect on phenolic composition. The wines showed some decrease in total acidity and an increase in pH with PVI-PVP. The application of PVI-PVP at the dose rates employed here did not affect the wine’s sensory characteristics significantly