This research concluded in getting experimental data about the composition of organic acids in wines obtained from varieties Cabernet-Sauvignon, Merlot, Pinot Noir, Rara Neagra, Feteasca Neagra, ...Shiraz (Syrah) produced within C.V. ”Cricova” S.A between 2015–2019 years. Also, it was argued the need to apply the malolactic fermentation simultaneously with alcoholic fermentation in order to increase the quality of young dry red wines, which allows the launch of the finished product in a restricted period of time. The degradation of malic acid in wine was achieved by malolactic fermentation bacteria, removing the excessive fresh taste of young wines ”Primeur” and ”Virgin”.
In order to elucidate the aroma components of wine produced in the Loess Plateau region of China, volatile compounds of young wines from Cabernet Sauvignon, Cabernet Gernischet and Chardonnay ...varieties grown in the new ecological region were investigated for the first time in this research. Among the volatile compounds analyzed by HS-SPME with GC-MS, a total of 45, 44 and 42 volatile compounds were identified and quantified in Cabernet Sauvignon, Cabernet Gernischet and Chardonnay wines, respectively. In the volatiles detected, alcohols formed the most abundant group in the aroma compounds of the three wines, followed by esters and fatty acids. According to their odor active values (OAVs), 18 volatile compounds were always present in the three wines at concentrations higher than their threshold values, but ethyl octanoate, ethyl hexanoate, and isoamyl acetate were found to jointly contribute to 92.9%, 93.3%, and 98.7%, of the global aroma of Cabernet Sauvignon, Cabernet Gernischet and Chardonnay wines, respectively. These odorants are associated with "fruity'' and ''ripe fruit'' odor descriptors.
Background and Aims
Governo all'uso toscano (GUT) is a traditional winemaking practice where withered grapes are added to a freshly fermented wine. This results in a second alcoholic fermentation and ...a distinctive wine, in which there is renewed interest. Grape withering is problematic for winemakers, however, both in terms of cost and risks. It is therefore important to determine the minimum amount of withered grapes needed to typify the wine in order to minimise risks and costs.
Methods and Results
During the trials, Sangiovese grapes were withered for 2 months in a dedicated room, a ‘fruttaio’, with a resulting mass loss of about 40%. Afterwards, withered grapes (5–20% berry mass/wine mass) were added to a Control wine to reproduce the GUT procedure. The GUT technique significantly changed the chemical profile of the wines. Ethanol, colour intensity and hue increased, while acidity decreased. Malolactic fermentation occurred simultaneously with the second alcoholic fermentation in all GUT wines, but not in the Control wines. The GUT practice significantly changed the volatile profile, including the concentration of several primary grape compounds, such as aromatic alcohols, C6 compounds and terpenoids, and of several fermentation compounds.
Conclusion
Under the experimental conditions, the optimal amount of withered grapes added to the base wine was 5%.
Significance of the Study
The study described the oenological effects of GUT and the optimisation of the amount of withered grapes required to make a wine with this characteristic winemaking practice clearly recognisable.
Thirty-two samples of commercially available Greek wines were analysed in order to determine the content of biogenic amines. The method involves pre-column dansylation of the amines and subsequent ...solid phase extraction (SPE) of the derivatives through C
18 cartridges. For the analysis, RP-HPLC (reversed phase-high performance liquid chromatography) coupled with fluorimetric detection at excitation and emission wavelengths of 320 and 523
nm, respectively was used. All amines measured had recoveries over 85%. The highest detection limit was for agmatine (0.18
mg
l
−1). Putrescine, cadaverine, histamine and isoamylamine are the most abundant amines in the samples analysed. The relative concentrations of biogenic amines expressed in mg l
−1 had as follows: putrescine
>
histamine
>
isoamylamine
>
ethylamine
>
methylamine
>
cadaverine
=
tyramine
=
agmatine
=
tryptamine. Higher amounts of biogenic amines were generally detected in wines, aged for long periods in barrels or in bottles. However, young wines contained lower amounts of these compounds as they were directly bottled after winemaking and have not undergone any further maturation processing. Moreover, less acid wines gave rise to higher histamine contents.
Twenty-five volatile compounds of 71 white, 53 rose and 70 red commercial young wines, representative for the young wines commercialized under the Denomination of Origin (DO) “Vinos de Madrid” ...(Spain) were analyzed by gas chromatography-flame ionization detector (GC-FID) and gas chromatography-mass spectrometry (GC-MS). Odor activity values (OAV) of 21 of them were calculated, also. Twenty-four of the 25 determined odor compounds were found in the three types of wines, which means that the differences between white, rose and red wines are essentially quantitative, rather than qualitative. 4-Vinyl-guayacol was typical only for the white wines. Thirteen of the 21 odor compounds with determined OAVs had significant relevance to the global aroma of the white and rose and 12 of the red wines. Among them (in diminishing order of odor importance) ethyl octanoate, ethyl hexanoate, isoamyl acetate and isovaleric acid were the most determinant for the aroma of the white and rose wines, whereas, ethyl octanoate, isovaleric acid, isoamyl acetate and ethyl hexanoate were for the red wines. Discriminant statistic analysis showed that the isoamylic alcohols, higher major alcohols, ethyl hexanoate, acetates, ethyl octanoate, 4-vinyl-guaiacol and decanoic acid were the most significant compounds in the differentiation between the white, rose and red young wines. The same analysis showed correct classification of 96.6% of the wines (92.1% cross-validation), according to their type (white, rose or red).
Phenolic profiles of young monovarietal white and red wines from the Central Serbia were investigated. Quantification of phenolics was done using ultra-high-performance liquid chromatography (UHPLC) ...coupled with a diode array detector and a triple-quadrupole mass spectrometer. Generally, red wines were characterised with higher phenolics content when compared to the white wines. This applies also for the total phenolics content (TPC) and radical scavenging activity (RSA) values. Among all the samples, the red wine from autochthonous Serbian variety 'Prokupac' stood out with unique composition, showing the highest TPC, RSA and the highest concentration of the individual phenolics. Finally, based on a specific phenolic pattern, principal component analysis (PCA) indicated clustering of red and white wines, with the 'Prokupac' as a prominent outlier.
Principal component analysis (PCA) was used to identify the main sources of variation in the Fourier transform infrared (FT-IR) spectra of 329 wines of various styles. The FT-IR spectra were gathered ...using a specialized WineScan instrument. The main sources of variation included the reducing sugar and alcohol content of the samples, as well as the stage of fermentation and the maturation period of the wines. The implications of the variation between the different wine styles for the design of calibration models with accurate predictive abilities were investigated using glycerol calibration in wine as a model system. PCA enabled the identification and interpretation of samples that were poorly predicted by the calibration models, as well as the detection of individual samples in the sample set that had atypical spectra (i.e., outlier samples). The Soft Independent Modeling of Class Analogy (SIMCA) approach was used to establish a model for the classification of the outlier samples. A glycerol calibration for wine was developed (reducing sugar content < 30 g/L, alcohol > 8% v/v) with satisfactory predictive ability (SEP = 0.40 g/L). The RPD value (ratio of the standard deviation of the data to the standard error of prediction) was 5.6, indicating that the calibration is suitable for quantification purposes. A calibration for glycerol in special late harvest and noble late harvest wines (RS 31−147 g/L, alcohol > 11.6% v/v) with a prediction error SECV = 0.65 g/L, was also established. This study yielded an analytical strategy that combined the careful design of calibration sets with measures that facilitated the early detection and interpretation of poorly predicted samples and outlier samples in a sample set. The strategy provided a powerful means of quality control, which is necessary for the generation of accurate prediction data and therefore for the successful implementation of FT-IR in the routine analytical laboratory. Keywords: FT-IR spectroscopy; principal component analysis; outliers; glycerol; wine
In young wines potassium hydrogen tartrate is always present in supersaturating concentration and crystallizes spontaneously. The aim of this study is to obtain kinetic parameters, which explain the ...stability of young wines during the stabilization treatments. The kinetic and equilibrium parameters were evaluated and discussed. The heating factor has a decisive influence on the reaction rate of potassium hydrogen tartrate precipitation in young wines. An increase of temperature leads to a decrease in efficiency of stabilization process and to an enhancement of the activation energy of the system. According to the obtained experimental results, the optimal regime for production and stabilization of young wines has been established.
The present work was undertaken to study the effect of the treatment temperature on the potassium bitartrate stability and composition of young wines. The thermodynamic parameters, namely ∆G°, ∆H°, ...∆S° were calculated to predict the nature of potassium hydrogen tartrate (KHT) precipitation. According to the achieved results, the exothermal nature and thermodynamical feasibility of KHT precipitation in young wines were established. Based on thermodynamics, negative ∆G°, ∆H° values and positive ∆S° value give a spontaneous KHT process at lower temperatures.
•First work to study carbonic maceration in Tempranillo and Graciano simultaneously.•Carbonic maceration greatly influences red wine color parameters.•Wine phenolic composition depended on the ...fraction obtained by carbonic maceration.•Wines were clearly discriminated according to their phenolic composition.
The current study aims to gather information about the color-related characteristics and the monomeric phenolic composition of carbonic maceration (CM) wines. The study was conducted over two vintages, with two different grape varieties. Color-related general parameters and wine monomeric phenolic composition were determined in both free-run and press CM fractions and were compared to conventional winemaking (CW). Overall, wines made by CM had lower phenolic content and color intensity. The analysis of wine detailed phenolic composition showed that CM wines were characterized by low contents of anthocyanins and flavonols. In contrast, free-run wine obtained by CM had the greatest concentration of flavanols and hydroxycinnamic acids, probably due to the presence of stems during the fermentation. In conclusion, vinification by CM leads to important differences in wine phenolic composition and, as consequence, on wine color properties. These differences could play an important role in wine sensorial properties and wine aging potential.
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