An assessment of the effects of wine volatiles on the perception of taste and astringency in wine

The objective of this work is measuring the effect of different volatile extract compositions on the perception of taste, astringency, global intensity and persistence of wine. Six Spanish wines, two from Chardonnay and four from Tempranillo grapes, all of them showing different chemical and sensory characteristics, were selected. Wines were separated into volatile and non-volatile fractions by solid phase extraction and lyophilisation and further liquid extraction, respectively. Eighteen “reconstituted wines” were prepared, combining different volatile extracts and different non-volatile matrices and adjusting ethanol content to 12% (v/v), and were further described by a specifically trained sensory panel. Taste attributes (sweetness, acidity, bitterness), astringency, aroma intensity, global intensity and persistence were assessed in both, original and “reconstituted” wines by using a numerical category scale. The sensory properties of the original wines were retained by their corresponding “reconstituted samples”. The sensory assessment of the “reconstituted wines” showed that the addition of volatile fruity extracts from white wines brought about a decrease in astringency and bitterness and an increase in sweet perception in all cases. While global intensity and persistence of white wine matrices were also increased, they did not change in red wine matrices, which suggests that the volatile fraction plays only a secondary role in these attributes of red wines. Similarly, the effects of replacing the volatile fraction of a red wine by volatile extracts from other red wines were small and inconsistent, which confirms that taste and astringency are primarily driven by non-volatile molecules in these wines.     

Binding capacity of brown pigments present in special Spanish sweet wines

Some special Spanish sweet wines are obtained by addition of a sweetening and coloring agent called grape syrup, which is obtained by heating must to give a dark and highly caramelised liquid, with similar consistency than other syrups. The aim of this work was to establish the influence of the addition of boiled must or “grape syrup” on the aroma and colour of sweet wines focussing specially on the possible binding effect on volatile compounds. The influence of must polyphenols was also studied, so, a wine sweetened with a “grape syrup” free of polyphenols was also elaborated. As it was expected, the addition of grape syrups gave an increase in the levels of furfural related compounds, and sweet wines showed lower concentrations of terpenes, ethyl esters, organic acids and acetates of alcohols than the control wine. The capacity of brown polymers present in grape syrups to bind these volatile compounds is discussed. Furthermore, colour parameters were also studied and significant differences were found for all of them between sweet wines and control wine.     

Nitrogen compounds and polysaccharides changes during the biological ageing of sherry wines

Biologically aged sherry wines are elaborated by the so called “criadera” and “solera” system, which essentially involves development of the yeast on the wine surface forming a film velum for several years. In this work, a study on the changes that take place in polysaccharide and nitrogen compounds during the elaboration of sherry wines has been undertaken. The evolution of monosaccharides derived from polysaccharides as well as of amino acids and polypeptides have been investigated in wine samples at different stages of the elaboration process (young wines, “sobretablas”, “criaderas” and “solera”). Mannose, galactose, glucose and arabinose were detected in all analyzed wines; mannose being the most abundant carbohydrate, particularly in wines that aged longer. Glucose and galactose content also increased during the biological ageing of these wines, whereas arabinose concentration lowered during all period. Nitrogen compounds experimented a decrease and even some amino acids were not detected at the end of the ageing. Considering the increase in mannose and the decrease in amino acid levels, it is presumable that autolysis and growth of yeast occur at the same time during the elaboration of the sherry wines.     

Employment of near infrared spectroscopy to determine oak volatile compounds and ethylphenols in aged red wines

The aim of this work was to study the ability of NIR spectroscopy to determine oak volatile compounds and ethylphenols levels in aged red wines. For this purpose 510 wines aged with different storage time and in different oak barrel types were analyzed. Calibration models were developed from SBSE-GC–MS and NIR data using partial least squares (PLS) regression. In order to validate the calibration, full cross validation was employed. Results showed that the calibration statistics were very good (R² > 0.86) for all the compounds studied. In wines aged in French and in American and French oak barrels, and in “reserva” and “gran reserva” wines, the residual predictive deviation (RPD) obtained was higher than 1.5 in all the compounds and it was higher than 2 in some of the cases. In conclusion, near infrared spectroscopy can be used as a rapid tool to determine oak volatile compounds and ethylphenols in aged red wines.     

Contribution of free and glycosidically-bound volatile compounds to the aroma of muscat “a petit grains” wines and effect of skin contact

Free and glycosidically-bound volatile compounds of must, skin and wine from Muscat “a petit grains” cultivated in Spain were determined, and the effect of different skin contact times on the aroma composition and sensory characteristics of wines was investigated. Must and wine had a large quantity of mono-terpenes, mainly linalool, geraniol, and nerol. The most abundant glycosylated fraction was the mono and poly-oxygenated terpenes, followed by benzene compounds and norisoprenoids. Must skin contact at 18 °C during 15 and 23 h produced an important increase in the free and bound varietal compounds, which suggests the use of glycosidic enzymes, together with skin maceration, to increase wine aroma. From a sensory standpoint, must skin contact was very positive, since it brought about an increase in the fresh and fruity characteristic of the wines, and they also had more body.     

SPME–GC method as a tool to differentiate VOC profiles in Saccharomyces cerevisiae wine yeasts

The aim of this work was to study the variability of 36 Saccharomyces cerevisiae wild strains isolated from different grape varieties and from two very distant zones, located in Northern and Southern Italy. The strains were differentiated on the basis of parameters of technological interest, such as resistance to antimicrobial compounds frequently present in wine, and the production of volatile aromatic compounds (VOC), determined by SPME procedure in the experimental wines obtained by inoculated fermentations. The VOC profile allowed to differentiate the yeasts in function of isolation area: S. cerevisiae isolated from Southern Italy grapes were able to produce more volatile compounds than those from Northern Italy. The compounds synthesized by all the yeasts, besides the ethanol, were 3-methyl-1-butanol and ethyl acetate. The production of acids during the alcoholic fermentation was a characteristic of Southern yeast strains. The screening of S. cerevisiae strains for technological parameters, such as sulphur dioxide, copper and ethanol resistance or hydrogen sulphide production, revealed similar behaviour for sulphur dioxide resistance among Northern and Southern S. cerevisiae strains. Copper resistance and sulphur dioxide production were correlated to isolation area: S. cerevisiae “Northern” strains showed higher copper resistance and lowest hydrogen sulphide production than that exhibited from “Southern” strains.     

Chemical and chromatic characteristics of Tempranillo,Cabernet Sauvignon and Merlot wines from DO Navarra aged in Spanish and French oak barrels

The oenological quality of Spanish oak wood from Navarra (Quercus petraea Liebl.) in relation to French wood of recognised quality in cooperage has been evaluated. We have studied the effects of the Spanish wood on wine evolution during ageing, in regards to chromatic characteristics, polyphenols, and volatile compounds related to oak wood, in three different mono-varietal wines (cv. Tempranillo, cv. Cabernet Sauvignon and cv. Merlot) from the Origin Denomination Navarra. The results were compared with those obtained for the same wines aged in French oak barrels from central regions of France, obtained from five different French and Spanish cooperages.     

橡木片对霞多丽葡萄酒发酵的影响

该文研究在发酵过程中添加法国中度烘烤橡木制品对霞多丽干白葡萄酒的影响,增加霞多丽干白葡萄酒酿造工艺的选择性.接种酵母菌进行酒精发酵的同时在葡萄汁中添加法国中度烘烤橡木制品,未添加橡木制品发酵的样品为对照样,分别在发酵降糖50％和酒精发酵结束时测定理化指标、有机酸与挥发性化合物的含量.结果表明:添加橡木制品发酵对霞多丽葡萄酒化学物质有一定影响,其总高级醇、总橡木挥发性化合物含量较高.而对照样的葡萄酒中总酸和总酯含量较高,总高级醇含量是添加橡木制品发酵的葡萄酒中总高级醇含量的70％～85％,而酸类物质含量是添加橡木制品发酵葡萄酒的2倍.     

Multivariate classification of rice wines according to ageing time and brand based on amino acid profiles

Discrimination of Chinese rice wines according to ageing time and brand using amino acid profiles was presented in this study. Free amino acids (16) in 98 rice wines were simultaneously determined using high-performance liquid chromatograph-diode array detection (HPLC-DAD). Then the experimental data was subjected to multivariate analysis. Principal component analysis (PCA) was employed to differentiate samples from various ageing times (3, 9, 11 and 15 months) and brands (“pagoda”, “kuaijishan”, and “guyuelongshan”). Partial least square discriminant analysis (PLS-DA) and full (leave-one-out) cross-validation were used to develop classification models. The overall correct classification rate for different ageing times and brands was 99.7% and 94.9%, respectively. The proposed method shows an effective strategy for the detection of mislabelling of rice wines.     

不同果酒挥发性风味物质对比分析

以4种不同果酒（青梅酒、桃花酒、杨梅酒、桑葚酒）为研究对象,采用顶空固相微萃取（HS-SPME）结合气相色谱-质谱联用法（GC-MS）对其挥发性风味成分进行测定,并对其挥发性风味物质进行主成分分析（PCA）,建立综合评分模型对不同果酒挥发性成分进行综合评价。结果表明,4种不同果酒中共检测出79种挥发性风味成分,其中,醇类17种、醛类16种、酮类8种、酯类18种、脂肪酸类5种、萜烯类11种及其他类4种,醇类物质相对含量最高,青梅酒、桃花酒、杨梅酒、桑葚酒的醇类相对含量分别为30.17%、25.15%、28.08%、28.41%。PCA结果表明,4种果酒综合得分按高低顺序依次为青梅酒>桑葚酒>杨梅酒>桃花酒。     

Validation of a Method for Analysis of Aroma Compounds in Red Wine using Liquid–Liquid Extraction and GC–MS

An analytical method for determination of volatile composition of wines using sample preparation by liquid–liquid extraction and gas chromatography coupled to mass spectrometry for separation and detection has been developed and validated. Extraction of volatile compounds was performed in dichloromethane, and 1-octanol was added as an internal standard. Kékfrankos red wine produced in Villány wine region in Hungary was used as a model wine for testing and validation of the method. The developed method allowed satisfactory determination of 33 volatile compounds in the wines. Compounds analyzed include alcohols, esters, lactones, fatty acids, furans, and nitrogen compounds. The calibration curves of the four reference compounds used (2-phenyl ethanol, ethyl nonanoate, butyrolactone, and tyrosol) were linear in all cases with correlation coefficients (R ²) ranging from 0.9951 to 0.9992. The accuracy of the method was checked with a standard addition method (recovery 92.2–103 %), showing good repeatability and reproducibility (RSD?<?10 %).     

Improvement of volatile composition of wines by controlled addition of malolactic bacteria

The effect of malolactic fermentation (MLF) on the volatile composition of red wines was studied by inoculation with selected lactic acid bacteria. Four wines were inoculated with different Oenococcus oeni (syn. Leuconostoc oenos) strains, the major malolactic species found in wines, and one was inoculated with a Lactobacillus sp. strain. A non inoculated wine was also analyzed to act as a control. Malolactic fermentation and evolution of non volatile compounds were followed by HPLC and after the depletion of the malic acid present in wine the volatile compounds were extracted and analyzed by gas chromatography with flame ionization and mass spectrometry. Wines which had undergone the MLF showed a significant increment in total higher alcohols, esters and acids that are important in the sensory properties and quality of wine.