Changes in phenolic compounds and colour in pale Sherry wines subjected to fining treatments

 Changes in the concentrations of hydroxybenzoic acids, hydroxycinnamic acids and their esters, monomeric and dimeric derivatives of flavan-3-ol, and flavonols, as well as in the UV-visible absorbances of pale Sherry wines were studied. The wines were subjected to four different fining treatments: casein + bentonite, casein + bentonite + activated charcoal, casein + bentonite + polyvinylpyrrolidone (PVPP) and casein + bentonite + Riduxhigh. Based on the results, the treatments including activated charcoal and PVPP were the most effective at decreasing the overall concentration phenolic compounds, with no significant difference between them. Likewise, these treatments provided the best results in relation to wine colour in the visible spectral region, and particularly at 420 nm, at which wavelength browning compounds are usually measured. Received: 24 March 1997 / Revised version: 11 June 1997     

Evolution of the colour,antioxidant activity and polyphenols in unusually aged Sherry wines

The present paper reports the results of a study monitoring several key analytical parameters in a set of aged samples of vintages from 1999 back to 1935. The analysed parameters were: colour, antioxidant activity, low molecular weight phenolics, index of total polyphenols and SO₂ content.     

Changes in phenolic compounds in lentils (Lens culinaris) during germination and fermentation

 Germination and fermentation have been proposed to improve the nutritive value of legumes. This paper reports the changes that occur in phenolic compounds in lentils (Lens culinaris var. vulgaris) during germination and fermentation. Levels of low-molecular-weight phenolic compounds (benzoic acids and aldehydes, hydroxycinnamic acids and derivatives, flavan-3-ols and procyanidins) were determined. Germination did not appreciably vary the content of phenolic compounds, although important structural changes in procyanidin-type compounds were observed. Fermentation led to a general increase in the content of phenolic compounds. Gentisic acid, p-hydroxyphenylpropionic acid, tryptophol and three other unknown compounds were detected in fermented lentils, but not in raw lentils. The influence of these changes on the potential antinutritional effects associated with phenolic compounds in legumes, as well as on the antioxidant properties attributed to these compounds is discussed. Received: 16 December 1996 / Revised version: 6 March 1997     

Direct determination of phenolic compounds in Sicilian wines by liquid chromatography with PDA and MS detection

Phenolic compounds in Sicilian wines were directly detected using an HPLC with a PDA detector coupled on-line with a MS system equipped with Electrospray Ionisation (ESI) source operated in the negative-ion mode and a quadrupole mass analyzer. In this work, MS spectra were recorded at different voltage, to obtain structural elucidations in addition to molecular mass informations. The different response of the compounds identified has been also evaluated. MS characteristics of cis- and trans-piceid were determined on the basis of the response obtained with the ESI interface.     

Changes in the profile of volatile compounds in wines stored under oxygen and their relationship with the browning process

 Eight young white wines produced in Aragon from Macabeo and Chardonnay grapes were stored under an oxygen atmosphere in the dark at room temperature. Changes in the colour and volatile compound composition were recorded over a period of 13 weeks. Significant changes in the volatile compound composition were detected through analysis of variance (ANOVA) of repeated measures, considering both grape variety and browning tendency as discriminant categories. The amounts of fatty acids and fermentation esters in the wine were significantly changed by the oxidative storage. Some of these changes can be attributed to acid-ester hydrolysis equilibria, but not others, such as the decrease in concentrations of octanoic and decanoic acids. The oxidative storage also affected most of the unsaturated fatty-acid-derived compounds: trans-2-octenal, trans-2-nonenal, trans-2-decenal and 1-octen-3-ol were all found to increase in the first stages of storage, while hexanol decreased slightly. Volatile phenols behaved very differently: while phenol and 4-ethylphenol initially increased and later decreased, eugenol increased through the process and 4-vinyl-guaiacol disappeared. Benzaldehyde and furfural increased while methionol and terpenols disappeared. Only furfural was found to be linked with the tendency of the wine to brown, while only linalool and benzaldehyde were found to be linked whith the grape variety. The levels of some odorants previously isolated by sniffing detection were temptatively monitored, and significant changes in their concentrations were found to occur during the process. Received: 16 December 1996 / Revised version: 27 March 1997     

Pre-bottling use of dehydrated waste grape skins to improve colour,phenolic and aroma composition of red wines

Different dehydrated waste grape skins from the juice industry were added into aged and young red wines as an innovative way of compensating for colour loss before bottling. After addition of grape skins, colour intensity of wines increased a mean 11% and a maximum of 31% with predominance of the red component. Total polyphenols mean increase was 10% with a maximum value of 20%. Analysis of low molecular weight phenolic compounds by HPLC–DAD showed a significant (p < 0.05) content increase of the bioactive compounds gallic acid, (+)-catechin, (−)-epicatechin, and (E)-resveratrol. Anthocyanins content also increased at an average of 50 mg/l. The volatile profile of wines analysed by SBSE–GC–MS was only moderately influenced by the treatments. Mixtures of dehydrated waste grape skins were useful to improve the colour and polyphenol profile of red wines, considering them a useful tool for correcting colour loss before bottling.     

Changes in the profile of volatile compounds in wines stored under oxygen and their relationship with the browning process

 Eight young white wines produced in Aragon from Macabeo and Chardonnay grapes were stored under an oxygen atmosphere in the dark at room temperature. Changes in the colour and volatile compound composition were recorded over a period of 13 weeks. Significant changes in the volatile compound composition were detected through analysis of variance (ANOVA) of repeated measures, considering both grape variety and browning tendency as discriminant categories. The amounts of fatty acids and fermentation esters in the wine were significantly changed by the oxidative storage. Some of these changes can be attributed to acid-ester hydrolysis equilibria, but not others, such as the decrease in concentrations of octanoic and decanoic acids. The oxidative storage also affected most of the unsaturated fatty-acid-derived compounds: trans-2-octenal, trans-2-nonenal, trans-2-decenal and 1-octen-3-ol were all found to increase in the first stages of storage, while hexanol decreased slightly. Volatile phenols behaved very differently: while phenol and 4-ethylphenol initially increased and later decreased, eugenol increased through the process and 4-vinyl-guaiacol disappeared. Benzaldehyde and furfural increased while methionol and terpenols disappeared. Only furfural was found to be linked with the tendency of the wine to brown, while only linalool and benzaldehyde were found to be linked whith the grape variety. The levels of some odorants previously isolated by sniffing detection were temptatively monitored, and significant changes in their concentrations were found to occur during the process. Received: 16 December 1996 / Revised version: 27 March 1997     

The effect of some processing variables on non-coloured phenolic compounds in port wines

 The non-coloured phenolic fraction of fortified port wines was studied. Trials using several mash-extraction techniques which may be used during port wine making were evaluated for their effectiveness by measuring qualitative and quantitative differences in phenolics. Total phenolic compounds measured by spectrophotometry and HPLC analysis were compared, and the greater values obtained using spectrophotometry are attributable to the contribution of anthocyanins and non-phenolic UV-absorbing compounds. Quantitative and qualitative differences in composition were observed depending on the extraction mode. The greatest total phenolic content was found in port wine made by traditional foot treading, while early addition of extra alcohol to the mash had a neutral or negative effect on the yield of phenolic compounds. Received: 20 March 1997     

Influence of prefermentative maceration temperature on the colour and the phenolic and volatile composition of rosé wines

Prefermentative maceration for 8 h at 5, 10 and 15 °C was used to make rosé wines, and changes in their colour (colour intensity (CI), tone and CIELAB parameters), phenolic compounds (classic indices and individual compounds) and volatile compounds (major and minor) were monitored from the must stage to wines until 6 months after bottling. The 15 °C maceration temperature provided wines with the highest CI, a* and C* values, the greatest malvidin‐3‐glucoside content and the lowest alcohol and ethyl acetate levels. Only in these wines were terpenols released after 6 months in the bottle. The wines produced at 5 °C had the highest ester levels, which also remained more stable during storage. When using maceration temperature as the differentiating variable in a discriminant analysis, volatile compounds were important contributors. However, colour and phenolic compound parameters were important when sampling time was used as the differentiating variable. The best scoring wines in an informal sensory evaluation test were those subjected to 15 °C maceration, while the least appreciated were those macerated at 5 °C. Copyright © 2005 Society of Chemical Industry     

Prebiotic effects of yacon (Smallanthus sonchifolius Poepp. & Endl), a source of fructooligosaccharides and phenolic compounds with antioxidant activity

Montepulciano is one of the most famous and important red-berried grapes of Italy. This article presents and discusses a comparative study of aroma profile and phenolic content of the Montepulciano wine from the Marches and the Abruzzo regions. The volatile composition of wines was determined by using headspace solid phase microextraction (HS-SPME) coupled with gas chromatography-mass spectrometry (GC-MS). The PDMS fibre was chosen. The dominating esters in Montepulciano wines were ethyl hexanoate, ethyl decanoate, and ethyl octanoate, whereas phenyl ethanol and 3-methyl-1-butanol were dominating alcohols.Phenolic compounds, namely gallic acid, p-coumaric acid, trans-ferulic acid, caffeic acid, trans-resveratrol, (+)-catechin and (−)-epicatechin, were examined using HPLC-MS with direct injection of wine samples. The total phenolic content of the analysed wines was in the range of 30.4-61.9 mg l⁻¹. The presence of high amounts of esters seems to characterise the volatiles of Montepulciano wines from the Marches, whereas a high level of alcohols was found in Montepulciano wines from Abruzzo. Moreover, multivariate chemometric techniques, such as cluster analysis and principal component analysis, supported this thesis. Headspace solid phase microextraction and gas chromatography-mass spectrometry were used to analyse 20 commercial wine samples (Montepulciano monovarietal red wines) from the Marches (10 samples) and Abruzzo (10 samples).     

Changes in phenolic composition of Tinta Miúda red wines after 2 years of ageing in bottle: effect of winemaking technologies

The major phenolic compounds (catechins, oligomeric and polymeric proanthocyanidins, and anthocyanins) in Tinta Miúda red wines made by various winemaking technologies (i.e., fermentation with carbonic maceration, fermentation with stem contact and fermentation without stem contact) were analyzed after 2 years of ageing in bottle, and compared with the data on their younger state (i.e., at the time of bottling). The concentrations of all individual phenolic compounds analyzed were significantly changed and their degradation rates (percent of decrease) were highly dependent on the winemaking technology used. The degradation of anthocyanins was, in general, more remarkable than that of catechins and proanthocyanidins. Catechins and proanthocyanidins in carbonic maceration wine appeared more stable than in skin fermentation wines, during ageing in bottle.     

Differences in the phenolic composition and sensory profile between red wines aged in oak barrels and wines aged with oak chips

The aim of this study was to evaluate the similarities or differences in the phenolic composition and the sensory characteristics between wines traditionally aged in new French and American barrels for different periods of time, and wines aged for 30 days with different kinds (different geographical origin al toasting degree) of oak chips. This study was carried out with two grape varieties, Mencía and Tinta del País, and in two consecutive vintages. The results obtained indicated that it was not possible to obtain wines aged with chips with sensory characteristics similar to those aged for a long time in new barrels, independently. However, the results showed that the use of oak chips could be a good alternative for elaborating young wines with slight olfactory and gustative wood notes quite similar to wines aged in new barrels for short periods of time (about three months).     

Changes in contents of phenolic compounds during maturing of barrique red wines

Concentrations of derivatives of benzoic and cinnamic acids and furaldehyde were studied during maturing of a red wine (a mixture of Cabernet Sauvignon and Merlot) in barrique barrels (Quercus robur). Samples were taken at three-week intervals over 6 months. The influence of degree of toasting of the wood on the amount of phenolic compounds in barrique wine was also investigated. The samples were pre-separated using a solid-phase extraction on an RP 105 polymeric sorbent and analysed by high-performance liquid chromatography with UV-DAD detection. Gallic, protocatechuic, p-hydroxybenzoic, vanillic, caffeic, syringic, p-coumaric, ferulic, benzoic and ellagic acids and p-hydroxybenzaldehyde, vanillin, 2-furaldehyde, 5-methoxy-2-furaldehyde and 5-methyl-2-furaldehyde were identified in the extracts of natural and toasted wood chips and in the extracts of the wine. Syringaldehyde was identified only in the extracts of the toasted wood chips. Ellagic acid can be regarded as a characteristic compound of barrique wine ageing and its constant level during some periods could become a marker of maturity of barrique wines. Due to the absence of furaldehydes in natural wines, these compounds can be considered as typical components of barrique wines and so they can serve as a marker of authenticity of barrique wines.     

Comparative study of phenolic compounds in Cabernet Sauvignon wines made in traditional and Ganimede fermenters

Chemical profiles of anthocyanin and non-anthocyanin phenolics of Cabernet Sauvignon wine made by two different winemaking techniques (traditional vinification and Ganimede method) were determined by high performance liquid chromatography–mass spectrometry (HPLC–MS). Particularly, effect of extraction on and subsequent stability of the phenolic compounds from the end of fermentation to bottling were investigated. The results showed that the total anthocyanin content was higher in the young wines produced in the Ganimede fermenter. The anthocyanin contents in these wines subsequently decreased significantly after two years of ageing. By contrast, the traditional vinification was slightly better than the Ganimede to yield the non-anthocyanin phenolics. This indicates that the Ganimede fermenter might be suitable for the production of brightly coloured red wines for early consumption, which could save time and labour cost for industrial production of highquality wines.     

A survey of phenolic compounds in Spanish wines of different geographical origin

 The phenolic composition of red and white wines from four Spanish Appellations of Origin (official classification of Spanish wines) was investigated. Different hydroxybenzoic and hydroxycinnamic acids, catechins, procyanidins, alcohols, stilbenes and flavonols were identified. Additionally, the ketone 2,3-dihydroxy-1-guaiacylpropan-1-one was identified for the first time in red wines aged in oak barrels. The concentration of most of the phenolic compounds quantified was higher in red wines than in white wines, as would be expected from the different methods of vinification and the grape varieties used. These differences could also contribute to differences in the antioxidant ability of these wines. The multivariate analysis applied to the phenolic compounds quantified allowed the relationships among these compounds to be examined and the origin of the wines to be distinguished. Received: 31 May 1999 / Revised version: 16 August 1999     

Influence of the heterogeneity of grape phenolic maturity on wine composition and quality

Nowadays, consumers demand red wines with deep colour, soft tannins and fruit scents, but these wines can only be obtained from grapes with complete phenolic maturity. Diverse methods have been proposed for measuring phenolic maturity. However, all these methods only provide the average value and do not consider any possible heterogeneity. Throughout ripening, grapes were separated according to their density, which revealed the existence of a large heterogeneity. Grapes at harvest were also separated by density in three groups. The higher the density of the grapes the higher ethanol content, pH, colour intensity, total phenolic index and anthocyanin and proanthocyanidin concentrations, and the lower the titratable acidity and bitterness of the wines. When the grapes were denser the wines were also better balanced in flavour and mouthfeel sensation. These results suggest that grape heterogeneity may influence the final wine composition and quality and therefore it should be considered at harvest.     

Polyphenolic compounds and antioxidant properties of selected China wines

Thirty-seven China wines, produced from different geographical origins, were examined in this study. The antioxidant activity of wines was measured by different analytical methods: oxygen radical absorbance capacity (ORAC), reducing power, 2,2-azino-di-(3-ethylbenzothialozine-sulphonic acid) (ABTS), 2,2-diphenyl-1-picrylhydrazyl (DPPH·), hydroxyl radical-scavenger activity, superoxide radical-scavenger activity, lipid peroxidation and chelating capacity. Furthermore,total phenols, total flavonoids, total flavanols and total anthocyanins of wines were determined. As expected, the red wines had much higher phenolic content and antioxidant capacity than rosé wines or white wines. Among the red wines, Cabernet Sauvignon and Muscat Hamburg, respectively, represented the wines with the highest and lowest phenolic contents and antioxidant capacity. Among the white wines, Italian Riesling had the lowest phenolic content and antioxidant capacity. Taken together, a close relationship between phenolic contents and antioxidant capacity, for all wines, was observed.     

Influence of wine-making protocol and fining agents on the evolution of the anthocyanin content,colour and general organoleptic quality of Vinhão wines

This paper reports the evolution, over two years, of the anthocyanin content, colour and organoleptic quality of red wines prepared from a single batch of Vinhão grapes by means of three different protocols (maceration/fermentation with conventional pumping-over or in rotary vats, and fermentation after initial carbonic maceration), with and without the use of four different fining agents (polyvinylpolypyrrolidine, gelatin, egg albumin, and casein). Carbonic maceration led to lower anthocyanin levels and less intense coloration than the other two methods immediately following vinification, but during storage the carbonic maceration wines underwent less colour degradation than the others, so that after two years the colour density differences among the three were negligible. Wines treated with fining agents tended to have somewhat lower anthocyanin levels and, especially in the case of PVPP, less intense colouration than untreated wines, and their colour was at best only marginally more stable during storage, but they nevertheless generally achieved higher panel ratings for organoleptic quality than untreated wines, especially as regards taste.     

Determination of phenolic compounds in wines: Influence of bottle storage of young red wines on their evolution

Various analytical methods based on the HPLC-DAD technique were used to determine 38 phenolic compounds in red wines. While anthocyanins and hydroxycinnamic acids were determined by direct injection of wine samples, hydroxybenzoic acids, catechins, procyanidins and flavonols required an analytical pretreatment involving liquid–liquid partitioning with ethyl ether followed by solid-phase extraction on C₁₈ mini-columns. The proposed analytical methods were used to establish the phenol composition of Mencía and Brancellao, two varietal young red wines, and its influence on colour stability during storage in bottles for one year. At the end of malolactic fermentation, Mencía wine was found to contain much greater amounts of anthocyan pigments than was Brancellao wine. This resulted in a higher colour density but a weaker hue in Mencía wine than in Brancellao wine. Phenolic compounds evolved similarly in both wines during storage; changes in such compounds involved a decrease in the levels of monomeric anthocyanins, phenolic acids, epicatechin and flavonols, and an increase in those of procyanidins. The absence of a relationship between the changes in colour density and monomeric anthocyanins in both wines suggests that copigmentation and polymerization with other phenolic compounds (viz. phenolic acids, catechins and/or flavonols) prevail over degradation of the pigments.