Degradation of oligomeric procyanidins and anthocyanins in a Tinta Roriz red wine during maturation

A young red Tinta Roriz wine was stored for three months at different temperatures (12, 22, 32, 42 degrees C) under anaerobic conditions and after adjusting the SO2 to 0, 50, 100 mg/l. Changes in wine phenolic composition, especially the procyanidins and anthocyanins were measured using HPLC reverse phase. Dimeric (B1, B2, B3, B4), galloylated dimeric (B1-3-O-gallate, B2-3O-gallate, B2-3'-O-gallate) and trimeric procyanidins (C1, T2) were quantified during the maturation of the red wine, and their losses were found to be logarithmic with time. Temperature exerts a marked influence on the progressive degradation of procyanidins, while the presence of SO, slows down the degradation. Comparing their activation energies the dimer procyanidins B1, B2 and B3 appear to be more stable to degradation while trimer T2 and B2-3-O-gallate are most reactive. Concerning the anthocyanins, the acylated monoglucosides degrade faster than the other monoglucosides and the p-coumaric acid acylated pigments disappear faster than the acetic acid acylated pigments

Interactions between protein fining agents and proanthocyanidins

A comparative fining trial was conducted in a laboratory scale to study the influence of protein fining agents on proanthocyanidins, colour and browning potential of white wine. The monomeric flavanols were significantly depleted by casein, and gelatine with low molecular weight (MW) distribution, and isinglass obtained from fish swim bladder (MW > 94.0, containing some bands in the range 94.0–43.0 and at 20.1 kDa). However, the other gelatines and isinglass with a MW polydispersion below 20.1 kDa did not interact significantly (P < 0.05) with these compounds. In contrast, the oligomeric compounds were not decreased by swim bladder isinglass. It was also observed that neither of the isinglasses decreased the polymeric flavanols significantly (P < 0.05). Although casein and potassium caseinate had similar MW distributions and isoelectric points, potassium caseinate decreased the polymeric flavanols, whereas casein did decrease monomeric, oligomeric and polymeric flavanols significantly (P < 0.05). The degree of polymerisation of polymeric proanthocyanidins that remained in the fined wine decreased significantly (P < 0.05) after addition of protein fining agents except when potassium caseinate was used. Casein, potassium caseinate and swim bladder isinglass induced a significant (P < 0.05) decrease in wine colour (A420nm), a decrease in browning potential and a decrease in turbidit

Evolution of proanthocyanidins in bunch stems during berry development (Vitis vinifera L.)

Proanthocyanidins from bunch stems of two red varieties (Castelao Frances and Touriga Francesa) and one white variety (Viosinho)(Vitis vinifera L,) harvested in 1998, were separated into monomers (catechins), oligomers (degree of polymerization ranging from 2 to 12-15) and polymers (degree of polymerization &gt;12-15), and then quantified during grape development (40 d before veraison until ripening). In addition, low molecular weight catechins [(+)-catechin and (-)-epicatechin], dimeric procyanidins (B1, B2, B3, B4), galloylated dimeric procyanidins (B13-0-gallate, B2-3-0-gallate, B2-3'-0-gallate), and trimeric procyanidins (C1, T2) from grape stems were quantified by HPLC, At harvest the polymeric fraction was the most abundant (28.0 - 35.8 mg . g-1 stem). For the three grape varieties, the content of catechins, oligomeric and polymeric fractions decreased during berry development mainly after veraison, Crape stems are also an important source of proanthocyanidins in the grape cluster when compared to the flavanol content in seeds. From an industrial point of view, stems seem to be an important source of proanthocyanidins for potential use as nutriceutical, enological products, chemical standards or even in winemaking to regulate flavanol composition in wine.

Evolution of anthocyanins during grape maturation of two varieties (Vitis vinifera L.), Castelao Frances and Touriga Francesa

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Effect of commercial mannoproteins on wine colour and tannins stability

Available at ScienceDirectCommercial oenological products containing mannoproteins have the purpose of preventing tartrate salts precipitation or achieving wines with a better mouth-feeling. The evaluation of the influence of three commercial mannoproteins on colour and tannin stability of three different red wines (two from Touriga Nacional and one from Alfrocheiro and Aragonês varieties) was studied. The evolution of colour through time was similar for all modalities, resulting in an increase of polymeric pigments and colour hue and a decrease of other parameters, suggesting that there was no influence of commercial mannoproteins on colour stability. The tannin profile evolution showed a possible stabilizing effect of one of the commercial products for tannins with an mDP between 8 and 14. It is possible that the commercial mannoproteins used in this work have some influence on the tannin aggregation evolution, contributing to the delay of tannin polymerisation in red wines

Effect of Winery Yeast Lees on Touriga Nacional Red Wine Color and Tannin Evolution

Red wine aging on lees is a w inemaking practice u sed to achieve more rounded and less astringent wines. In two different trials, external yeast lees were added to a red wine and their effects on wine color and tannin evolution during aging were studied. Results indicated that the addition of yeast lees did not affect color stabilization during the studied period. Color compounds a nd condensed tannins were rapidly adsorbed to t he yeast lees at the beginning of the experiment. There was a retarding effect on proanthocyanidin polymerization reaction by the addition of yeast lees, leading to the maintenance of low and medium molecular weight tannins in solution. Two different interactions were observed: first, proanthocyanidin adsorption by the yeast lees, primarily ones with the highest polymerization degree, and second, the retarding of proanthocyanidin polymerization, likely by the mannoproteins released by yeast lees. The age of the yeast lees was a factor in mannoprotein release and its effect in wineinfo:eu-repo/semantics/publishedVersio

Glycosidic aroma compounds of some portuguese grape cultivars

Determinação dos compostos glycosidicos do aroma de uvas poruguesa

The power of oral and nasal calls to discriminate individual mothers and offspring in red deer, Cervus elaphus

[Background]: In most species, acoustical cues are crucial for mother-offspring recognition. Studies of a few species of ungulates showed that potential for individual recognition may differ between nasal and oral contact calls. [Results]: Vocalizations of 28 hinds and 31 calves of farmed Iberian red deer (Cervus elaphus hispanicus) were examined with discriminant function analyses (DFA) to determine whether acoustic structure of their oral and nasal contact calls encodes information about the caller's identity. Contact calls were elicited by brief separation of individually identified animals by a distance over 10 m or by a bar fence. Both oral and nasal calls of both hinds and calves showed high potential to discriminate individuals. In hinds, individuality was significantly higher in the oral than in the nasal calls, whereas in calves, individuality was equally well expressed in both oral and nasal calls. For calves, the maximum fundamental frequency was higher and the duration was longer in oral calls than in nasal calls. For hinds, the maximum fundamental frequency and the duration were indistinguishable between oral and nasal calls. Compared to the pooled sample of oral and nasal calls, separate oral or nasal call samples provided better classifying accuracy to individual in either hinds or calves. Nevertheless, in both hinds and calves, even in the pooled sample of oral and nasal calls, the degree of individual identity was 2-3 times greater than expected by chance. For hinds that provided calls in both years, cross-validation of calls collected in 2012 with discriminant functions created with calls from 2011 showed a strong decrease of classifying accuracy to individual. [Conclusions]: These results suggest different potentials of nasal and oral calls to allow the discrimination of individuals among hinds, but not among red deer calves. The high potential of individual recognition even with the pooled sample of oral and nasal calls allows mother and young to remember only one set of acoustic variables for mutual vocal recognition. Poor between-year stability of individual characteristics of hind oral and nasal calls would require updating keys to individual recognition each calving season.This study was supported by the Russian Scientific Foundation, grant No 14-14-00237 (for IV, EV, OS and VM) and by Ministerio de Economía y Competitividad, Spain, project AGL2012-38898 (for TL, AG and LG).Peer Reviewe

Rootstock and harvest season affect the chemical composition and sensory analysis of grapes and wines of the Alicante Bouschet (Vitis viniffera L.) grown in a tropical semi-arid climate in Brazil

Aim: In this study, we aimed to evaluate the composition of grapes and wines of the Alicante Bouschet variety from a tropical semi-arid area in Brazil, by studying two rootstocks and harvests in different semesters (climates) of the same year. Methods, Results: Vines of Vitis vinifera L., Alicante Bouschet, a teinturier variety, were grown in a tropical semi‑arid climate in Brazil. The phenolic composition of the grapes and wines was measured to assess how they had been affected by two rootstocks (IAC 572 and 1103P) and two harvest seasons, Semester 1 and Semester 2 (in this region, a grapevine produces two harvests per year, with an intra-annual climate variability). The grapes and wines were subjected to the usual physicochemical analyses, as well as to spectrophotometric and chromatographic analyses. Sensory analysis was carried out by professional tasters. The results show that there is a rootstock effect and a harvest season effect for several parameters on grape composition, as well as on the resulting wines. The grapes from vines grafted onto IAC 572 rootstock contained higher titratable acidity, tartaric acid, malic acid, total anthocyanins, total proanthocyanidins in skins and seeds and polymeric tannins in skins. The grapes from vines grafted onto 1103P rootstock contained higher concentrations of total phenols and non-flavonoids, total monomeric anthocyanins, monomeric and polymeric tannins in the seeds. The second semester wines were higher in total anthocyanins, total phenols, flavonoids and non-flavonoids, condensed tannins and low molecular weight flavanols, astringency potential, colour intensity, titratable acidity, total dry extract and alcohol content. Conclusions: The results demonstrate an influence of rootstock and harvest season (semester/climate) on grape and wine composition. Some of the grape and wine phenolic compounds analysed individually (some monomeric anthocyanins and low molecular weight flavanols) were higher in the first semester than in the second. The overall phenolic parameters determined in grapes and wines from the second semester were higher than those from the first. According to the sensory analyses, the semester (climate) effect was stronger than the rootstock effect, and the wines from the second semester received the highest scoring than those from the first semester, mainly for olfactory and gustatory attributes. Significance and impact of the study: This study uses a holistic methodology, mainly with respect to the phenolic compounds, to examine the combined effects of rootstocks and intra-annual climate variability on grape and wine composition. The results of this study may contribute to future research, as well as help the producers and wine companies of tropical regions to tailor viticultural and oenological parameters, in order to improve the quality and typicality of the productsinfo:eu-repo/semantics/publishedVersio

Chemical composition and sensory profile of Syrah wines from semiarid tropical Brazil - rootstock and harvest season effects

This study aims to characterise the chemical compositions and sensorial profiles of wines made with Syrah grapes over two harvest seasons (first and second semester), over in different calendar years, from vines on two different rootstocks (1103P and IAC 313). Wine chemical composition and sensory profile were influenced by both rootstock and harvest season. Syrah wines on IAC 313 were favoured with higher concentrations of, petunidin 3-O-acetylglucoside (3.7 mg/L), malvidin 3-O-acetylglucoside (17.8 mg/L), malvidin 3-O-coumarylglucoside (4.4 mg/L), petunidin 3-O-coumarylglucoside (2.0 mg/L), peonidin 3-O-coumarylglucoside (1.4 mg/ L), monomeric flavanols (23.6 mg/L), oligomeric tannins (183.0 mg/L), total condensed tannins (1037.7 mg/L), dimer B1 (9.8 mg/L), B4 (5.0 mg/L), trimer C1 (3.1 mg/L) and calcium (80 mg/L). Syrah wines on 1103P had higher concentrations of total anthocyanins (375.6 mg/L, catechin (8.6 mg/L), epicatechin (12.6 mg/L), dimer B2 (21.0 mg/L), B1 3-O-gallate (1.8 mg/L), B2 3′-O-gallate (6.0 mg/L) and total flavanols (53.4 mg/L). The sensory profiles of the Syrah wines were influenced by rootstock followed by, mainly in relation to aromatic attributes. Syrah wines on IAC 313 were scored more highly by the tastersinfo:eu-repo/semantics/publishedVersio