Fining of wines using proteins is a standard practice in the winemaking process. Gelatine is a common fining agent used for red wines. However, the consumer demand for wines that are free of ...animal-derived products has reinforced the search for alternative protein sources such as yeast origin as the latter is originally present in wine. In 2012, the International Organization of Vine and Wine (OIV) authorized yeast protein extract (YPE) as a processing aid for the fining of musts and wines (OIV-Eno 452–2012). The present work aimed at better understanding the fining mechanisms of a specific YPE, to evaluate the part played by interactions in solution with polyphenols, but also at the interfaces with suspended particles. Polyphenols from the soluble phase of red wine were separated from the suspended particles by centrifugation, and these particles were resuspended in a wine model solution. Interactions with YPE were studied with each fraction separately through static multiple light scattering (SMLS) using the Turbiscan Lab® apparatus and optical microscopy. The impact on wine color and astringency was assessed by UV–visible spectrophotometry and BSA assay test. Faster aggregation and sedimentation kinetics were observed with gelatine than with YPE, but the levels of clarification and lees were similar for both fining agents after a couple of hours (4 h maximum). Gelatine resulted in higher tannin and pigment removal, likely to decrease astringency but also derived pigments involved in red wine color stability. Meanwhile, the impact of the YPE was moderate, likely to modulate astringency while preserving wine color and structure. In addition to interacting directly with polyphenols in solutions such as gelatine, YPE exhibited the additional ability to trap particles and promote their sedimentation in the absence of tannins. This double performance of the YPE used in this work, is likely to guarantee an effective fining of red wines as well as for low tannin content matrices such as rosé and white wines.
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•The mechanism of red wine fining with a yeast protein extract and a gelatine was studied.•Both fining agents interacted with tannins promoting their precipitation with particles.•Precipitation with tannin and pigments was more pronounced with gelatine.•YPE was able to trap particles and promote their sedimentation without tannins.
It is well recognized that the aging process is a critical step in winemaking because it induces substantial chemical changes linked to the organoleptic properties and stability of the finished ...wines. Therefore, this study aimed to investigate the influence of different types, utilization times, and volumes of aging barrels on the metabolite profile of red wines, produced from Thai-grown Shiraz grapes, using a non-targeted proton nuclear magnetic resonance (sup.1H-NMR) metabolomics approach. As a result, 37 non-volatile polar metabolites including alcohols, amino acids, organic acids, carbohydrates and low-molecular-weight phenolics were identified. Chemometric analysis allowed the discrimination of wine metabolite profiles associated with different types of aging containers (oak barrels vs. stainless-steel tanks), as well as the utilization times (2, 6 and >10 years old) and volumes (225, 500 and 2000 L) of the wooden barrels employed. Significant variations in the concentration of formate, fumarate, pyruvate, succinate, citrate, gallate, acetate, tyrosine, phenylalanine, histidine, γ-aminobutyrate, methionine and choline were statistically suggested as indicators accountable for the discrimination of samples aged under different conditions. These feature biomarkers could be applied to manipulate the use of aging containers to achieve the desired wine maturation profiles.
A simple, rapid and high-throughput approach was developed for authentication of red wine for the first time, by combining spectral results from matrix-assisted laser desorption/ionization mass ...spectrometry (MALDI-MS) and direct analysis in real time mass spectrometry (DART-MS). By coupling with orthogonal partial least squares discrimination analysis (OPLS-DA), this approach enabled successful classification of 535 wines from 8 countries, with the correct classification rates of 100% on the calibration set and over 90% on the validation set for almost all countries, and 26 potential characteristic markers selected. Compared to one single technique, this approach allowed detection of more compound ions, and with better fitting and predictive performances. The satisfactory differentiation results of vintages and grape varieties further verified the robustness of the approach. This study demonstrated the feasibility of combining multiple mass spectrometric techniques for wine analysis, which can be extended to other fields or to combinations of other analytical techniques.
► We optimized the analysis of resveratrol metabolic profile with 11 standards. ► We defined a resveratrol metabolic profile of 21 compounds. ► Resveratrol metabolites were accurately quantified, ...when standard available. ► The method was applied to a interventional study with red wine and a dealcoholized one. ► Resveratrol bioavailability could not be influenced by the alcoholic matrix of wine.
Resveratrol exerts a variety of biological and pharmacological activities, which are observed despite its extremely low bioavailability and rapid clearance from the circulation due to extensive sulfation and glucuronidation in the intestine and liver. In order to more accurately quantify all known resveratrol metabolites, a sensitive and optimized analytical assay was developed and validated by pure standards. Methodology improvements aimed to the chromatographic detection of disulfates and sulfoglucuronides, improving resolution of sulfates, by using a buffered solution, with recovery values of resveratrol and its metabolites, even of sulfates, of 99%. The adapted methodology was then applied to a clinical study with high cardiovascular risk subjects, after the moderate consumption of red wine (RW) or dealcoholized red wine (DRW) for 28 days. Up to 21 resveratrol metabolites, including those formed by gut and microbial metabolism, were identified in 24-h urine samples. Interestingly, after long-term consumption of RW and DRW, resveratrol metabolite concentration significantly increased in urine with no differences between the two interventions, indicating that bioavailability and biotransformation of resveratrol is not affected by the alcoholic matrix of wine. In summary, we established a sensitive analytical assay for the quantification of a wide resveratrol metabolic profile in human urine, also regarding gut microbial-derived metabolites, which may also be applied to blood and tissue samples. The resveratrol metabolic pattern might therefore act as an excellent marker for the efficacy of resveratrol in clinical and epidemiological studies for the study of the beneficial effects of grape product consumption. In this sense, having a more precise concentration value of all the resveratrol metabolites in target tissues would finally lead to a better interpretation of the obtained results.
To determine the concentrations of aroma compounds involved in the fruity aroma of red wines, an analytical method was developed and optimized using liquid–liquid extraction and gas chromatography ...coupled to mass spectrometry (GC/MS). The aim was to reduce sample preparation and analysis time, with a single sample preparation and a single injection being needed to quantify 43 compounds. 19 esters, 13 monoterpenes, 5 C13-norisoprenoids, and 6 C6-aldehyde and alcohol compounds were quantified in 14 red wines made from different grape varieties grown in the Mediterranean basin. Samples were selected based on typical varietal aroma by a panel of experts, who produced 7 olfactory descriptors linked to desirable or non-desirable wine aromas. The instrumental analysis showed variations in concentrations of the quantified compounds among the wines. The wines described using positive fruity descriptors had higher mean total concentrations of esters, C6-alcohols, monoterpenes, and C13-norisoprenoids. Some non-ester compounds were positively correlated with the fruity descriptors. Sensory profile results obtained by a panel of 16 trained judges revealed that the addition of non-ester compounds (including 2 cyclic esters) to a red wine initially described as having cooked fruit aromas had a positive contribution to some fresh fruity notes. This study opens up new avenues for research on the potential involvement of non-ester compounds in the fruity expression of red wines.
A rapid LC–MS/MS method for quantification of phenols and polyphenols in authentic wine samples with unrivalled sensitivity was developed. Excellent limits of detection in the low μg L
−1 range were ...achieved. Reversed phase HPLC employing sub-2
μm particles as stationary phase allowed high-throughput analysis with analysis times of 10
min for 11 compounds. The phenolic pattern was assessed in 97 authentic wine samples (stored under identical conditions without further treatment or modification) comprising eleven geographical Austrian regions, six grape varieties and five vintages. Canonical discriminant analysis was applied to the data set showing the suitability of the (poly)phenolic spectrum for classification of the wine samples. The method allowed a geographic discrimination of several grape varieties and a grape variety based discrimination of four regions. As a novel finding excellent (poly)phenol-based differentiation of the five investigated vintages (2003–2007) was achieved.
The main flavonols found in seven widespread Vitis vinifera red grape cultivars include the 3-glucosides and 3-glucuronides of myricetin and quercetin and the 3-glucosides of kaempferol and ...isorhamnetin. In addition, the methoxylated trisubstituted flavonols, laricitrin and syringetin, were predominantly found as 3-glucosides. As minority flavonols, the results suggest the detection of the 3-galactosides of kaempferol and laricitrin, the 3-glucuronide of kaempferol, and the 3-(6‘ ‘-acetyl)glucosides of quercetin and syringetin. The flavonol profiles based on the eight above-mentioned flavonols allowed the cultivar differentiation of the grape samples. With regard to flavonol biosynthesis in the berry skin, quercetin 3-glucuronide predominated at véraison, followed by quercetin 3-glucoside, and only trace amounts of trisubstituted flavonols were detected. The proportion of quercetin 3-glucoside remained almost constant during berry ripening, whereas the proportion of quercetin 3-glucuronide decreased and the other flavonols, especially myricetin 3-glucoside, increased their importance. In wines, flavonol 3-glycosides coexisted with their corresponding free aglycones released by hydrolysis. The presence of laricitrin, syringetin, and laricitrin 3-glucoside in red wines is reported here for the first time. The extent of hydrolysis was widely variable among wines made from the same grape cultivar, and the results suggest the influence of the type of aglycone and glycoside on the rate of hydrolysis. Due to hydrolysis, the differentiation of single-cultivar wines gave acceptable results only when aglycone-type flavonol profiles were used. Keywords: Flavonols; laricitrin; syringetin; grape; red wine; Vitis vinifera; cultivar authenticity; ripening
A preparative HPLC method was applied to aromatic red wine extracts. Twenty-five fractions with various flavors were thus obtained, and several aromatic reconstitutions were produced by mixing some ...of these fractions. Discriminative tests revealed that the omission of some fractions from the mixture of fruity fractions or the addition of others affected the overall expression of fruity aroma. Sensory profile analyses identified significant differences among aromatic reconstitutions in terms of intensity of black-berry, as well as fresh-, and jammy-fruit descriptors. A fraction with a very low fruity note (fraction 17) had an additive effect on the fresh fruity aroma, while fractions with caramel and lactic notes (fractions 3–5) had a masking effect on this aroma and an additive effect on the jammy-fruit aroma. Further analysis revealed that ethyl 2-hydroxy-4-methylpentanoate was eluted in fraction 17, while diacetyl, acetoin, acetic acid, and γ-butyrolactone were eluted in fractions 3–5. Omissions tests established that ethyl 2-hydroxy-4-methylpentanoate was responsible for enhancing black-berry and fresh-fruit aroma and that a combination of diacetyl, acetoin, acetic acid, and γ-butyrolactone, at levels between 2 and 40% of their perception thresholds, had the same hypoadditive effect on the overall and fresh fruity aroma as fractions 3–5.
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