Prediction of sauvignon blanc quality gradings with static headspace−gas chromatography−ion mobility spectrometry (SHS−GC−IMS) and machine learning

The main goal of the current study is the development of a cost-effective and easy-to-use method suitable for use in the laboratory of commercial wineries to analyze wine aroma. Additionally, this study attempted to establish a prediction model for wine quality gradings based on their aroma, which could reveal the important aroma compounds that correlate well with different grades of perceived quality METHODS: Parameters of the SHS−GC−IMS instrument were first optimized to acquire the most desirable chromatographic resolution and signal intensities. Method stability was then exhibited by repeatability and reproducibility. Subsequently, compound identification was conducted. After method development, a total of 143 end-ferment wine samples of three different quality gradings from vintage 2020 were analyzed with the SHS−GC−IMS instrument. Six machine learning methods were employed to process the results and construct a quality prediction model. Techniques that aim to explain the model to extract useful insights were also applied.

Impact of the non-volatile matrix composition on red wine aroma release and perception of olfactory and oral cues

Aroma and mouthfeel cues are the main characteristics defining red wine quality. During wine tasting, perceptual and physical-chemical phenomena leading to mutual interactions between volatiles and non-volatiles sensory active compounds, can occur. Aroma perception depends on the release of volatiles from wine, that is affected by wine constituents present in the medium (Pittari et al. 2021; Lyu et al. 2021). Our aim was to evaluate the effect of the non-volatile wine matrix composition (polyphenols, PPh) on the release and perception of red wine aromas by an experiment of matrix enrichment.

White wine light-strike fault: a comparison between flint and green bottles under the typical supermarket conditions

Consumer preference favors flint-glass wine bottles over the traditional dark-colored, but it is documented that light exposure can cause white wines to produce off-aromas and change in color, and consequently da[1]mage their quality. Aim of the study was to study the white wine shelf life under the typical supermarket conditions, by recording the light and temperature exposure, the colorimetric changes, and the light-strike fault. METHODS: One pilot experiment based on two white wines and eight-time points and one kinetic experiment based on four white wines and seven-time points were designed and realized using a typical supermarket shelf for 32 and 50 days, correspondently. By installing prototype sensors at 32 points of the shelf, the temperature, UV, IR, and Visible light exposure were registered every 10 min. Approximately 600 commercial wines, bottled in flint and colored glass, were used. The colorimetric changes of the wines were registered and the light-strike fault was evaluated.

GC-O and olfactoscan approaches to reveal premature aging markers in Chardonnay wine

Molecular markers of wine oxydation, such as sotolon or Strecker’s aldehydes that induce respectively nut or curry and boiled vegetables or wilted rose odors, can be percieved as a default by consumers. These volatile compounds are especially formed during the premature aging of wine, but it is likely that several contributing compounds are still unknown as is their combined contribution. This study was carried out to identify the markers of oxydation in Chardonnay wine by Gas Chromatography Olfactometry (GC-O) and to study the impact of these markers on the complex wine aromatic buffer using the Olfactoscan approach.A Chardonnay wine (2018-vintage), taken after malolactic fermentation without sulphites addition, was submitted to an artificial oxidation to simulate more or less prononced premature oxidation. Volatile compounds were extracted by Solid-Phase Extraction (SPE) and analysed by GC-O with a panel of 13 trained subjects. The same extract was also submitted to a second analysis based on the Olfactoscan technique, which allowed to evaluate the impact of each volatile compounds on the complex aromatic buffer of a non-oxidized wine delivered as background odor. Preliminary results revealed three types of behavior. On the one hand, several odor zones appeared only with the background odour, suggesting a synergy effect induced by the compounds in the aromatic buffer. Conversely, odor-active compounds could not be perceived within the background odor suggesting a masking effect. Finally several compounds were found to contribute as key odorants for wine oxydation once mixed with the aromatic buffer. These compounds are still to be identified using complementary techniques.

Understanding sweetness of dry wines: first evidence of astilbin isomers in red wines and quantitation in a one-century range of vintages

The gustatory balance of wines relies on sweetness, bitterness and sourness. In dry wines, sweetness does not result from the presence of residual sugar as in sweet wines, but is due to other non-volatile compounds. Such taste-active compounds are released during winemaking, by grapes, yeasts or oak wood and belong numerous chemical families [1]. Beyond this diversity, stereochemistry of molecules can also influence their sensory properties [2]. However, the molecular determinants associated with this taste have only been partially elucidated. Astilbin (2R, 3R) was recently reported to contribute to wine sweetness [3]. As its aglycon contains two stereogenic centers, three other stereoisomers may be present: neoisoastilbin (2S, 3R), isoastilbin (2R, 3S), and neoastilbin (2S, 3S). These compounds have already been observed in natural products, but never in wine. This work aimed at assaying their presence for the first time in wines as well as their taste properties.The isomers were synthesized from astilbin and purified by semi-preparative HPLC.

Influence of processing parameters on aroma profile of conventional and ecological Cabernet-Sauvignon red wine during concentration by reverse osmosis

Wine aroma represents one of the most important quality parameter and it is influenced by various factors (viticulture and vinification techniques, climate or storage conditions etc.). Wines produced from conventionally and ecologically grown grapes of same variety have different chemical composition and aroma profile [1]. Aroma profile of wine can be also influenced by additional treatment of wine, such as concentration of wine by reverse osmosis (RO). Reverse osmosis represents a pressure-driven membrane separation technique that separates the initial wine on the retentate or concentrate that is retained on the membrane, and permeate that passes through it [2]. Wine permeate usually containes water, ethanol, acetic acid and several low molecular weight compounds that can pass through the membrane. This property enables the use of reverse osmosis membranes for wine concentration, partial dealcoholization, acetic acid or aroma correction [3,4].

Differences in the chemical composition and “fruity” aromas of Auxerrois sparkling wines from the use of cane and beet sugar during wine production.

The main objective of this study was to establish if beet sugar produces a different concentration of “fruity” volatile aroma compounds (VOCs), compared to cane sugar when used for second alcoholic fermentation of Auxerrois sparkling wines. Auxerrois base wine from the 2020 vintage was separated into two lots; half was fermented with cane sugar and half with beet sugar (both sucrose products and tested for sugar purity). These sugars were used in yeast acclimation (IOC 2007), and base wines for the second fermentation (12 bottles each). Base wines were manually bottled at the Cool Climate Oenology and Viticulture Institute (CCOVI) research winery. The standard chemical analysis took place at intervals of 0, 4 weeks, and 8 weeks post-bottling. Acidity and pH measurements were carried out by an auto-titrator. Residual Sugar (g/L) (glucose (g/L), fructose (g/L)), YAN (mg N/L), malic acid, and acetic acid (g/L) were analyzed by Megazyme assay kits. parameters were analyzed by Megazyme assay kits. Alcohol (% v/v) was assessed by GC-FID. VOC analysis of base wines, finished sparkling wines, as well as the two sugars in model sparkling wine solutions, was carried out by GC-MS. VOCs included ethyl octanoate, ethyl hexanoate, ethyl butanoate, ethyl decanoate, ethyl-2-methylbutyrate, ethyl-3-methylbutyrate, ethyl 2-methyl propanoate, ethyl 2- hydroxy propanoate, 1-hexanol, 2-phenylethan-1-ol, ethyl acetate, hexyl acetate, isoamyl acetate and 2-phenylethyl acetate.

Impact of reduction alcohol techiniques in the aromatic chemical profile of rosé Tempranillo wines

Studying the impact of reducing alcohol techniques in the chemical composition of the aromatic profile of rosé Tempranillo wines from the spanish region of Castilla-La Mancha INTRODUCTION: In the last decades there has been an increseasing demand of wines with low or non-existing alcohol concentration due to the negative effects that alcohol has in health. In spite of that, there are not laws that protect these products, and there is also a great difficulty in the elaboration of these type of wines due to the increasing temperatures because of climate change. This is why the oenological industry has made great advances in the development of different techniques that could satisfy consumers’ demands without modifying wine quality. The most used techniques have been post-fermentative ones.

Analytical characterization of Oloroso Sherry in Sherry Cask seasoning and its influence in the ageing of brandy de jerez

Oloroso Sherry is a typical fortified wine from Jerez de la Frontera (south of Spain). It is one of the most used in the seasoning of oak barrels, called Sherry Cask, destined in this area for ageing brandies or condiments as wine vinegars. Brandy de Jerez is an European Geographical Indication for grape-derived spirits. Its special organoleptic characteristics are due to its traditional dynamic ageing in Sherry Casks. American oak is the most common wood employed in Jerez area, where Brandy de Jerez is exclusively manufactured. During ageing period of Sherry and brandies, the wood is not only a container, it is involved in several physicochemical process with the Sherry or the distillate. Oak wood is the responsible of the presence of many compounds in the products, affecting their aroma and chemical composition and having a high influence in their final quality. Moreover, the seasoned wood with Sherry wine could transfer the compounds from wine into the brandy, improving its aroma and flavor.

Does the location of wine cellars have significant impact on the evolution of madeira wine polyphenols?

Unlike table wines, Madeira Wine (MW,17-22% ABV) benefits from a long aging period under thermo-oxidative aging conditions, during which it gains its unique and complex flavour. A broad study is ongoing and aims to assess if the differences in the storage conditions impact significantly the evolution of MWs during canteiro aging. Considering that polyphenols have a significant role in the wine aging, we intended to appraise if there are significant differences in the evolution trends of polyphenols of MWs aging in different cellars under canteiro. Different MWs were aged into brand-new oak casks in two different wine cellars, one in Funchal (B) and other in Caniçal (Z). Temperature and humidity data were sensor recorded. RP-HPLC-DAD was used to perform the identification and quantification of polyphenols [1]. CIELab parameters were also assessed, using an UV-Vis spectrophotometer.

A mechanistic investigation of H/D scrambling processes in flavonoids

Several classes of flavonoids, such as anthocyanins, flavonols, flavanols and flavones, undergo a slow H/D exchange on aromatic ring A, leading to full deuteration at positions C(6) and C(8). Within the flavanol class, H-C(6) and H-C(8) of catechin and epicatechin are slowly exchanged in D2O to the corresponding deuterated analogues; even quercetin, a relevant flavonol representative, shows the same behaviour in a D2O/DMSOd6 1:1 solution. Detailed kinetic measurements of these H/D scrambling processes are here reported by exploiting the time-dependent changes of their peak areas in the 1H-NMR spectra taken at different temperatures. A unifying reaction mechanism is also proposed based on our detailed kinetic observations, even taking into account pH and solvent effects. Molecular modelling and QM calculations were also carried out to shed more light on several molecular details of the proposed mechanism.

What is the best time to harvest grapes destined for withering? Ripeness and dehydration length affect phenolic composition of Nebbiolo grapes

Sfursat di Valtellina is a DOCG reinforced wine produced in Valtellina from partially withered red grapes of Vitis vinifera L. cv. Nebbiolo. The grape ripeness degree and the dehydration process strongly influence the physicochemical characteristics of grapes [1, 2, 3]. In particular, grape skin and seeds contain several classes of phenolic compounds strictly associated with red wine quality, which are significantly affected by these factors [4]. The aim of this research is to assess the combined influence of different ripeness levels and withering rates on the standard chemical composition and phenolic profile of winegrape in order to provide new insights and approaches to the management of withering, searching for the valorization of grape potentialities.

Experimental vinification of withered grapes of Vitis vinifera “Muscat of Alexandria”

The objective of the present work is to investigate wine produced from dehydrated grapes and vinified according to classical Roman manuals.

METHODS – Locally produced Muscat of Alexandria’s grapes were used for the sweet wine production, grown in the experimental vineyard of Instituto Superior de Agronomia (Lisbon, Portugal). The grapes were harvested manually slightly over-ripe and subjected to greenhouse drying. After 7-10 days dried grapes were transported to an experimental winery for various operations (e.g., grape weighing, sorting, crushing/destemming). Several maceration protocols were used comprising the addition of saltwater and white wine to whole bunches or destemmed grapes. Fermentation was conducted with the addition of commercial yeast. The standard physico-chemical parameters of wines were determined according to the OIV standards.

Polyphenol targeted and untargeted metabolomics on rosé wines : impact of protein fining on polyphenolic composition and color

Color is one of the key elements in the marketing of rosé wines[1]. Their broad range of color is due to the presence of red pigments (i.e. anthocyanins and their derivatives) and yellow pigments, likely including polyphenol oxidation products. Clarifying agents are widely used in the winemaking industry to enhance wine stability and to modulate wine color by binding and precipitating polyphenols[2]. During this study, the impact of four different fining agents (i.e. two vegetal proteins, potatoe and pea proteins, an animal protein, casein, and a synthetic polymer, polyvinylpolypyrrolidone, PVPP) on Syrah Rose wine color and phenolic composition (especially pigments) was investigated. Color was characterized by spectrophotometry analysis using the CIELab system in addition to absorbance data. Fining using PVPP had the highest impact on redness (a*) and lightness (L*) parameters, whereas patatin strongly reduced the yellow component (b*) of the wine color. In parallel, the concentration of 125 phenolic compounds including 85 anthocyanins and derived pigments was determined by Ultra High Performance Liquid Chromatography coupled to elestrospray ionisaion triple-quadrupole Mass Spectrometry (UHPLC-QqQ-ESI-MS) in the Multiple Reaction Monitoring mode[3] .

Macromolecular characterization of disease resistant red wine varieties (PIWI)

Pilzwiderstandsfähige (PIWI) are disease resistant Vitis vinifera interspecific hybrid varieties that are receiving increasing attention for ability to ripen in cool climates and their resistance to grapevine fungal diseases. Wines produced from these varieties have not been characterized, especially regarding their macromolecular composition. This study characterised and quantified colloid-forming molecules (proteins, polysaccharides and phenolics) of red PIWI wines produced in the UK. METHODS: In 2019 6 wines were made from the PIWI varieties Rondo, Cabernet Jura, Cabernet Cortis, Cabernet Noir, Regent and Cabertin grown at the Plumpton Rock Lodge Vineyard in Sussex (UK) and harvested at similar level of maturity (TSS, pH and TA). All juice was chaptalized to the same potential alcohol of 12%. Small scale winemaking (1L) was performed in quadruplicate using Bodum® coffee plungers to manage maceration [1]. Residual sugar content, pH, and titratable acidity were monitored during fermentation. For finished wines, the protein and polysaccharide content was measured by HPLC-SEC [2], while the total phenolic content was assessed using the Folin-Ciocalteau method [3]. The protein profile of the wines was further investigated by SDS-PAGE [4]. RESULTS: Fermentations (n=24) were all carried out to completion within 8 days.

Terpenoids and norisoprenoids in italian red wines

AIM Terpene compounds are associated with floral notes and are characteristic of aromatic grape varieties such as Muscat (Jackson, 2008). They are generally considered to potentially contribute to the aroma of white wines. However, there is a growing interest towards the potential contribution of terpene compounds to the aroma of red wines. The aim of this work was to investigate the occurrence of different terpenes in red wines from Italian varieties. METHODS For this study wines from 11 mono-varietal Italian red wines from 12 regions were used (19 Sangiovese, 11 Nebbiolo, 10 Aglianico, 11 Primitivo, 10 Raboso del Piave, 9 Cannonau, 11 Teroldego, 3 Nerello, 9 Montepulciano, 7 Corvina). All samples were from vintage 2016 and none of them had been in contact with wood. A total of 19 terpenes and 7 norisoprenoids were analysed by mean of SPME-GC-MS analysis using a DVB-CAR-PDMS fiber. The wines were collected in the framework of the activities of the D-Wines (Diversity of Italian wines) project.

The use of Hanseniaspora vineae on the production of base sparkling wine

Non-Saccharomyces yeasts have been associated, for many years, with challenging alcoholic fermentation processes. However, during the last decade the use of non-Saccharomyces yeasts in wine production has become increasingly widespread due to the advantages they can offer in mixed inoculations with Saccharomyces cerevisiae (Sc). In this respect, Hanseniaspora vineae (Hv), in synergy with Saccharomyces spp, represents an interesting opportunity to impart a positive contribution to the aroma complexity of wines. In fact, it is a well-known producer of pleasant esters, such as 2-phenylethyl acetate. This study compares the performances of Hv (strain Hv-205) in sequential inoculation modality to Sc in three Chardonnay musts for base sparkling wine production. No significant differences were observed in basic chemical parameters between wines except for titratable acidity, with a significantly decrease (up to 1.5 g/L) in Hv processes due to malic acid degradation. The analysis of the aroma compounds revealed remarkable differences in concentration of volatile metabolites, among others up to 37-fold increase of 2-phenylethyl acetate. In contrast, lower concentration of its alcohol were detected, suggesting higher acetylation activity by Hv.

Determination of target compounds in cava quality using liquid chromatography. Application of chemometric tools in data analysis

According to the Protected Designation of Origin (PDO), Cava is protected in the quality sparkling wines made by the traditional Champenoise method were the wine realize a second fermentation inside the own bottle1. Geographical and human peculiarities of each bottle are the main way for the final quality2. The aim of this study is to find correlations and which target compounds are the most representative of the quality of two different grape varieties, Pinot Noir and Xarel·lo. The quality of these two types of grapes is being studied for each variety by a previous classification of the vineyard made by the company who provided the samples (qualities A,B,C,D, being A the better one and D the worst one). The target compounds studied are organic acids and polyphenols. The methodology for the determination of organic acids is HPLC-UV/vis and for some of them the enzymatic methodology.

Aroma composition of young and aged Lugana and Verdicchio

AIM Verdicchio and Lugana are two Italian white wines produced in the Marche and Garda lake regions respectively. They are however obtained using grape varieties sharing the same genetic background, locally known as Verdicchio in Marche and Trebbiano di Soave in Garda. Anecdotal evidence suggests that these two wine types exhibit distinctive aroma features. The aim of this work was to explore the existence of a recognizable odour profile for Lugana and Verdicchio, and whether specific aroma chemical markers could be identified. METHODS 13 commercial wines, 6 Lugana and 7 Verdicchio were used. Sensory analysis was done using sorting task methodology, assessing only odor similarities. A total of 53 volatile compounds were identified and quantified GC-MS analysis. Aging behaviors were also evaluated after an accelerated aging at 40 ° C for 3 months. RESULTS HCA analysis of sorting task data identified indeed two groups: one characterized by floral and minty notes and mostly associated with Lugana wines, the other characterized by spicy and toasted aromas and mostly associated with Verdicchio. From a chemical point of view, major differences between the two wines types were observed for cis-3-hexenol, methionol, phenylethyl alcohol, and geraniol.

Volatile compounds of base wines for the production of Lessini Durello sparkling wine

AIM Durello is a sparkling wine produced in the Lessini mountains near Verona. The wine is made from Durella grapes, a native white grape variety with a particularly high acidity. In spite of the small production area (375 ha for only 35 producers), there is a growing interest in this product. However, little is known about the aromatic profiles of these wines. The aim of this work was to characterize the aroma profile of Durella base wines suitable for the production of Lessini Durello sparkling wine. METHODS 14 base wines from Durella grapesfrom different producers were used for this study. Solid Phase Microextraction (SPME) and Solid Phase Extraction (SPE) sampling techniques coupled to GC-MS analysis allowed to identify and quantify a total of 62 volatile compounds. RESULTS Durello base wines showed relatively high levels of vitispirane, ß-damascenone, ß-citronellol and esters.