Enological Practices Research Articles

Enriched Red Wine: Phenolic Profile, Sensory Evaluation and In Vitro Bioaccessibility of Phenolic Compounds

The beneficial health effect of red wine depends on its phenolic content and the phenolic content in red wines is affected by ecological, agricultural, and enological practices. Enriched wines have been proposed as an alternative to increase the phenolic content in wines. Nevertheless, phenolic compounds are related to the sensory characteristics of red wines, so enrichment of red wines requires a balance between phenolic content and sensory characteristics. In the present study, a Merlot red wine was enriched with a phenolic extract obtained from Cabernet Sauvignon grape pomace. Two levels of enrichment were evaluated: 4 and 8 g/L of total phenolic content (gallic acid equivalents, GAE). Wines were evaluated by a trained panel to determine their sensory profile (olfactive, visual, taste, and mouthfeel phases). The bioaccessibility of phenolic compounds from enriched red wines was evaluated using an in vitro digestive model and phenolic compounds were quantified by High Performance Liquid Chromatography coupled to tandem mass spectrometry (HPLC-MS/MS). Enrichment increased mainly flavonols and procyanidins. Such an increase impacted astringency and sweetness perceived by judges. This study proposes an alternative to increase the phenolic content in wines without modifying other main sensory characteristics and offers a potential beneficial effect on the health of consumers.

In search for flavonoid and colorimetric varietal markers of Vitis vinifera L. cv Rufete wines

The better adaptation of autochthonous grape varieties to environmental changes is increasing the interest on them. Previous studies on Vitis vinifera L. cv Rufete, the flagship of DOP “Sierra de Salamanca”, demonstrated its phenolic potential to produce quality wines. The present study aims at discovering flavonoid (HPLC-DAD-MSn) and colorimetric (CIELAB) varietal markers in commercial Rufete wines (RW) that could be employed to discriminate them from those made with other varieties or mixtures. Compared to Tempranillo wines (TW), RW showed lower phenolic contents, with lower proportions of anthocyanins and flavonols but greater of flavanols. Principal Component Analysis applied to flavonoid and chromatic variables allowed varietal separation of the samples along PC2, which was mostly driven by %total prodelphinidins, %oligomeric procyanidins and Cab* (greater in TW) and by %monomeric procyanindins and L* (greater in RW) and, additionally, by the proportions of A-type vitisins, acetaldehyde-related pigments, quercetin 3-O-glucuronide and Quercetin/Myricetin ratio (all greater in RW). The results of the present study show that the typicity of Rufete grapes is quite preserved in the wines made with up to 95% of Rufete and 5% of Tempranillo grapes or wines and independently of the enological practices of the different wineries.

Moderate Wine Consumption and Health: A Narrative Review.

Although it is clearly established that the abuse of alcohol is seriously harmful to health, much epidemiological and clinical evidence seem to underline the protective role of moderate quantities of alcohol and in particular of wine on health. This narrative review aims to re-evaluate the relationship between the type and dose of alcoholic drink and reduced or increased risk of various diseases, in the light of the most current scientific evidence. In particular, in vitro studies on the modulation of biochemical pathways and gene expression of wine bioactive components were evaluated. Twenty-four studies were selected after PubMed, Scopus and Google Scholar searches for the evaluation of moderate alcohol/wine consumption and health effects: eight studies concerned cardiovascular diseases, three concerned type 2 diabetes, four concerned neurodegenerative diseases, five concerned cancer and four were related to longevity. A brief discussion on viticultural and enological practices potentially affecting the content of bioactive components in wine is included. The analysis clearly indicates that wine differs from other alcoholic beverages and its moderate consumption not only does not increase the risk of chronic degenerative diseases but is also associated with health benefits particularly when included in a Mediterranean diet model. Obviously, every effort must be made to promote behavioral education to prevent abuse, especially among young people.

Application of Immobilized Yeasts for Improved Production of Sparkling Wines

Verdejo sparkling wines from two consecutive vintages were elaborated following the “champenoise” method. The second fermentation was developed with the same free or immobilized Saccharomyces cerevisiae bayanus yeast strain, carrying out four batch replicates each year. The sparkling wines were analyzed after 9 months of aging, showing no significant differences among the two typologies in the enological parameters (pH, total acidity, volatile acidity, reducing sugars, and alcoholic strength), the effervescence, or the spectrophotometric measurements. The free amino nitrogen content was significantly higher in the sparkling wines obtained from immobilized yeasts, nevertheless, the levels of neutral polysaccharides and total proteins were lower. No significant differences in the volatile composition were found, except for only two volatile compounds (isobutyric acid and benzyl alcohol); however, these two substances were present at levels below their respective olfactory thresholds. The sensory analysis by consumers showed identical preferences for both types of sparkling wines, except for the color acceptability. The descriptive analysis by a tasting panel revealed that sensorial differences between both sparkling wines were only found for the smell of dough. Therefore, the use of immobilized yeasts for the second fermentation of sparkling wines can reduce and simplify some enological practices such as the procedure of riddling and disgorging, with no impact on the so-mentioned quality parameters.

Comparison of Chromatic and Spectrophotometric Properties of White and Red Wines Produced in Galicia (Northwest Spain) by Applying PCA.

Wine is a complex matrix composed of numerous substances and color has an important influence on its quality and consumer acceptance. Color is affected by numerous factors such as pre-fermentation and fermentation operations, ageing, contact or addition of certain substances. In this study, different chromatic parameters were determined in 99 wines (58 red and 41 white) made from Galician (Northwest Spain) grape varieties. These parameters were obtained by using simple, rapid, and inexpensive spectrophotometric methodologies: color intensity, hue, total polyphenols content (Total Polyphenol Index TPI, Folin–Ciocalteu index, FCI), total anthocyans, total tannins, and color coordinates measured by the CIELab system. The influence of ageing in barrels (red wines) or using chips (white and red wines) on these parameters was also studied. A principal component analysis (PCA) was carried out to characterize the wines according to their chromatic characteristics. Application of PCA to the experimental data resulted in satisfactory classifications of studied white and red wines according to the cited enological practices.

Decreased Leaf Potassium Content Affects the Chemical Composition of Must for Sparkling Wine Production

The must used to make sparkling wine has a low pH value and moderate sugar content, and its potassium content can have a strong influence. An excess of potassium often leads to an insufficient supply of magnesium, since potassium has a strong antagonistic effect on magnesium, and, consequently, to poorer photosynthesis and a poorer quality of the must. The aim of this study was to determine whether the application of foliar fertilizers based on magnesium, phosphorus, and amino acids could reduce leaf potassium content, affecting the reductions in sugar content and pH value and increasing the total acidity of the must. A fertilizer trial with three replicates was conducted on the cultivar Istrian Malvasia (TCtrl—NPK, TMg—NPK + Agromag (6% MgO), TMgP—NPK + Agromag + Fosforo (30% P2O5) i TMgPBS—NPK + Agromag + Fosforo + Bio Prot) in a random complete block design. The NPK fertilizer was applied in the autumn. Foliar fertilization was applied three times during the growing season (31 May, 7 July, and 22 August 2014), and leaf samples were collected for leaf analysis before each application. The results show that foliar fertilization significantly reduced leaf potassium content, especially when treated with magnesium alone (treatment TMg). In addition, foliar fertilization significantly lowered the pH and increased the sugar content of the must. The results obtained in this research give a scientific contribution to the creation of fertilizer treatments for vines with a positive effect on the basic chemical composition of the base wine and provide a good basis for further research in reducing the use of certain enological practices during production.

Characterization of key odor-active compounds in sweet Petit Manseng (Vitis vinifera L.) wine by gas chromatography-olfactometry, aroma reconstitution, and omission tests.

Petit Manseng (Vitis vinifera L.) has become a popular variety in China for the production of semisweet and sweet wines. However, few studies focused on investigating the molecular odor code of its key odorants. In this study, the key odor-active compounds of Chinese sweet Petit Manseng wine were identified by gas chromatography-olfactometry (GC-O) and gas chromatography-mass spectrometry (GC-MS). Fifty-five odorous zones were sniffed and identified by application of aroma extraction dilution analysis on a distillate prepared by liquid-liquid extraction and solvent-assisted flavor evaporation. Among them, isoamyl alcohol, ethyl octanoate, isovaleric acid, (E)-β-damascenone, and phenylethanol particularly displayed with highest flavor dilution factors above 1024. The quantification of volatiles by headspace solid-phase microextraction coupled with GC-MS and GC coupled with triple quadrupole MS/MS and a calculation of odor activity values (OAVs) indicated 23 volatiles with OAVs above 1. Ethyl hexanoate showed the highest OAV with 208.8, followed by (E)-β-damascenone (189.0), 3-mercaptohexanol (60.3), isoamyl acetate (45.4), and furaneol (40.1). The aroma of the sweet wine was successfully reconstituted by combining 42 aroma compounds in a model wine solution. 3-Mercaptohexanol, (E)-β-damascenone, furaneol, γ-octalactone + γ-decalactone + γ-hexalactone, and ethyl cinnamate had important influence on the aroma of sweet Petit Manseng wine assessed by omission tests. Moreover, the discrimination of wines from three regions was successfully achieved by partial least squares discriminant analysis based on quantitative results of key odorants. 3-Mercaptohexanol was considered as the most responsible for the region discrimination and had highest concentrations in Petit Manseng wines from Jiaodong Peninsula. PRACTICAL APPLICATION: Understanding of the knowledge in key odorants of Petit Manseng wines could be useful to improve wine quality through viticultural and enological practices.

Impact of Climatic Conditions on the Resveratrol Concentration in Blend of Vitis vinifera L. cvs. Barbera and Croatina Grape Wines.

The aim of this work was to investigate the effect of meteorological conditions on resveratrol concentration of red wines produced in Piacenza viticultural region (Italy). In this regard, six representative estates producing Colli Piacentini Gutturnio DOC (a blend of V. vinifera L. cvs. Barbera and Croatina) vintage wines were analysed for trans- and cis-resveratrol over an 8-year period (1998–2005). Grapes were taken from the same vineyard in each estate by using the same enological practices over the entire investigated period. The meteorological conditions corresponding to the production areas were recorded, and bioclimatic indices were calculated as well. Overall, cis-resveratrol concentration was negatively correlated to Huglin index and August mean temperature, whilst positive correlation coefficients were found when considering the Selianinov index and the rainfall of September.

3-Isobutyl-2-methoxypyrazine is neutrally perceived by consumers at usual concentrations in French Sauvignon and Fer wines from the Gaillac area

3-isobutyl-2-methoxypyrazine (IBMP) is a grape-derived aroma compound responsible for the bell pepper character of wine. It is still unclear whether this molecule is always negatively perceived by consumers. The objective of this study was to establish a consumer rejection threshold (CRT) for IBMP in French white and red wines from the Gaillac area made from Sauvignon and Fer respectively.The best estimate thresholds (BET) were determined by carrying out three-alternative forced choice (3-AFC) tests: 5.5 ng/L for Sauvignon and 16.8 ng/L for Fer. For the estimation of the CRT, consumers (n = 48) received pairs of samples consisting of a base wine and a base wine spiked with an ascending concentration of IBMP. They were asked to indicate which sample they preferred, and the CRT was calculated as the concentration for which the spiked sample was significantly rejected. CRTs were determined at 50 ng/L and 30 ng/L for Sauvignon and Fer respectively.Our findings indicate that IBMP is more acceptable in white wine than in red wine. As IBMP concentrations reported in the literature for Sauvignon and Fer are generally below CRT concentrations, IBMP appears to be neutrally perceived by consumers at usual concentrations in wines from Gaillac made from these two cultivars.Our findings tend to contradict the belief in the wine industry that consumers systematically reject ‘vegetative’ styles of wines, and do not encourage local winegrowers and winemakers to necessarily implement viticultural or enological practices to minimise IBMP concentrations in wine.

Characterization of red wine native colloids by asymmetrical flow field-flow fractionation with online multidetection

Colloids are an important component of wines, but their study is challenging due to their instability. Asymmetrical Flow-Field Flow Fractionation (AF4)-multidetection is here proposed as a suitable approach to isolate and characterize red wine colloids in native state. AF4 provided size-separation and enabled quantification of the colloidal content of two wines. The gyration radius of colloids was determined by multi-angle light scattering, and ranged between 25 and 50 nm. Analysis of the collected AF4-fractions showed that proteins, polysaccharides and phenolics were present in different proportions among fractions. The composition of AF4-fractions differed between wines. SDS-PAGE analysis of AF4-fractions indicated the presence of protein-phenolics sub-aggregates only in the fractions containing colloids with small radius. The results allowed proposing a model for red wine colloids structure, which comprises two coexisting entities, one made of covalently linked proteins-phenolics sub-aggregates interacting by non-covalent forces with polysaccharides, and a second in which only polysaccharides and phenolics are present. The proposed model is consistent with the reported relative stability of red wine proteins, a fact that can be due to the stabilizing activity of polysaccharides. Given that enological practices affect the extraction of proteins, polysaccharides and phenolics, AF4-technique represents a very promising tool to investigate the effects of these practices on wine colloidal aggregation and behavior.

Use of potassium polyaspartate for stabilization of potassium bitartrate in wines: influence on colloidal stability and interactions with other additives and enological practices

The research was aimed at verifying the efficacy of potassium polyaspartate (KPA), added at bottling, for prevention of the precipitation of potassium bitartrate (KHT). The stability of KHT was determined with the mini-contact test and the cold test. The effect of KPA on the colloidal stability of white and red wines was also studied. Turbidity, color, and total anthocyanins and flavonoids (red wines only) were monitored. In the first experiment, the stabilizing effect of KPA added at bottling, with or without Arabic gum, tannins, and filtration (0.45µm cut-off), was studied in comparison with metatartaric acid (MTA). KPA proved to have good stabilizing efficacy for prevention of KHT precipitation and maintained its effect in all trials after 1 year of bottle aging. On the contrary, all the trials with MTA became unstable after 6 months. Moreover, KPA did not modify wine turbidity and color. The filtration (0.45µm cut-off) did not reduce its stabilizing efficacy. In the second experiment, the effect of KPA added to a white and a red wine, respectively clarified with casein and gelatin or vegetal protein and/or bentonite, was studied. KPA did not cause any increase in turbidity or appreciable changes in the color of the white wines of the different trials. A preliminary treatment with bentonite can prevent the possible formation of haze in red wines after the addition of KPA. PRACTICAL APPLICATION: KPA prevented the precipitation of KHT in unstable white and red wines. The stabilizing effect persisted after 1 year of bottle aging. The oenologist does not need to adopt special prescriptions when using KPA in combination with Arabic gum or tannins in prebottling operations. A treatment with bentonite prevented the appearance of turbidity in red wines after the addition of KPA.

How to adapt winegrowing and winemaking practices to improve organic wine production sustainability?

In a very evolving context of drastic reduction of chemical inputs in the production of wines from the vine to the bottle (under both legislative and consumer pressures), adaptation of viticultural and enological practices and implementation of novel techniques are major challenges for organic winemakers. The potential interventions are linked in particular with the use of new vine varieties (grapevine varieties resistant to cryptogamic diseases) and the use of new biological inputs (specific inactivated yeasts) and/or technology coupling (dynamic crushing, centrifugation, etc.) to ensure complete fermentations, complete extraction, and to avoid oxidation reactions throughout the winemaking processing. By this approach, we tend to demonstrate that (bio)-technological innovations can also accompany the development of a “sustainable oenology.”

Changes in the Composition of Aroma and Phenolic Compounds Induced by Different Enological Practices of Croatian White Wine

1. Azzolini, M., Fedrizzi, B., Tosi, E., Finato, F., Vagnoli, P., Scrinzi, C., Zapparoli, G. (2012). Effects of Torulaspora delbrueckii and Saccharomyces cerevisiae mixed cultures on fermentation and aroma of Amarone wine. European Food Research and Technology, 235(2), 303-313. CrossRef Google Scholar

Chemical Transfers Occurring Through Oenococcus oeni Biofilm in Different Enological Conditions.

Chardonnay wine malolactic fermentations were carried out to evaluate the chemical transfers occurring at the wood/wine interface in the presence of two different bacterial lifestyles. To do this, Oenococcus oeni was inoculated into must and wine in its planktonic and biofilm lifestyles, whether adhering or not to oak chips, leading to three distinct enological conditions: (i) post-alcoholic fermentation inoculation in wine in the absence of oak chips, (ii) post-alcoholic fermentation inoculation in wine in the presence of oak chips, and (iii) co-inoculation of both Saccharomyces cerevisiae and O. oeni directly in Chardonnay musts in the presence of oak chips. Classical microbiological and physico-chemical parameters analyzed during the fermentation processes confirmed that alcoholic fermentation was completed identically regardless of the enological conditions, and that once O. oeni had acquired a biofilm lifestyle in the presence or absence of oak, malolactic fermentation occurred faster and with better reproducibility compared to planktonic lifestyles. Analyses of volatile components (higher alcohols and wood aromas) and non-volatile components (Chardonnay grape polyphenols) carried out in the resulting wines revealed chemical differences, particularly when bacterial biofilms were present at the wood interface. This study revealed the non-specific trapping activity of biofilm networks in the presence of wood and grape compounds regardless of the enological conditions. Changes of concentrations in higher alcohols reflected the fermentation bioactivity of bacterial biofilms on wood surfaces. These chemical transfers were statistically validated by an untargeted approach using Excitation Emission Matrices of Fluorescence combined with multivariate analysis to discriminate innovative enological practices during winemaking and to provide winemakers with an optical tool for validating the biological and chemical differentiations occurring in wine that result from their decisions.

Current Perspective on Arsenic in Wines: Analysis, Speciation, and Changes in Composition during Production.

Arsenic, a naturally occurring metalloid found in certain foods, exists in various redox states and as inorganic and organic species, each with varying levels of toxicity. International regulatory bodies have imposed allowable maximums for total arsenic in wine ranging between 100 and 200 μg/L. Typical commercial wine levels are within these limits. However, a better understanding of viticultural and enological practices impacting total arsenic and arsenic species in grapes and wines is needed to ensure levels remain low. This perspective discusses current information on factors impacting the arsenic content of grapes and wines and the analytical approaches for monitoring inorganic and organic species.

A Model for Predicting Wine Quality in a Rhône Valley Vineyard

Core Ideas This modeling study to evaluate wine quality was based on a highly extensive and unique dataset. The model was validated with the actual scores attributed by the international press. This work can serve as a basis for studies in other vineyards. A model was developed as a tool to evaluate wine quality via submodels that represent soil, plants, meteorology, agronomic variables, various vineyard parameters, grape (Vitis vinifera L.) characteristics, and enological practices. The model is based on a highly extensive and unique dataset collected from a single Rhône Valley vineyard (Domaine de Beaurenard) in southern France and the expertise of its winemaker. This modeling study is a first step toward simulating the quality of a wine on the basis of 88 variables in the vineyard and 56 enological variables. The model was validated by comparing the scores predicted by the model with actual scores given by the international press for 49 modeled wines. At the end of the study, the model was compared against other statistical models. Through this model, winemakers can predict future wine quality early and develop improved business strategies. This modeling study was created for and applied directly to the studied situation (Châteauneuf du Pape, Côtes du Rhône, and Rasteau) and is not directly transferable to other situations. Nonetheless, it can serve as a basis for studies in other vineyards because, with the development of precision farming and the multiplication of sensors in agronomy, most wineries will soon have access to the necessary data to model the quality of their wine.

Investigation of geographic origin of wine from border regions: Potential limitations and possibilities of different analytical methods and combinations of methods to identify the correct side of the border

In the presented project the investigation on discrimination of geographic origin of wine in from border areas is carried out. Authentic wine samples from the border areas of Austria, Czech Republic, Slovakia (and from Serbia) are investigated and compared by applying different physico-chemical methods (e.g. IRMS, NMR, ICP-MS, ICP-OES, EPR, HPLC, UV-VIS, etc.). The comparison of the data sets from the participating countries and the different applied methods will show, to which extent a differentiation can still be achieved in the border areas of the respective countries, which methods prove most efficient and sensitive and if a combination of methods will lead to an increased sensitivity. Furthermore, we also investigate the causes for the potential differentiation, which might be environmentally determined, due to different agricultural and/or enological practices. Results from the first investigated vintage 2016 show a good separation of the respective geographic origins by isotope ratios and element concentrations as well as by other parameters. The relevant parameters for differentiation now have to be critically evaluated to exclude potential lab influences.

Identification of the potential inhibitors of malolactic fermentation in wines

Abstract This exploratory work aims to identify the potential inhibitors of lactic bacterial growth and to propose enological practices to guarantee the occurrence of spontaneous malolactic fermentation (MLF) in wines from traditional and double-pruning management harvests in southeast Brazil. One white wine from a summer harvest and one red wine from a winter harvest that failed to complete MLF were utilized as comparative models to identify inhibitor compounds to lactic bacteria. Wine composition, alcoholic-fermentation temperature and bacterial strain contribute to the success or failure of MLF. Temperatures below 12 °C during alcoholic fermentation decrease lactic bacterial metabolism and may impair the bacteria’s growth after yeast cells lysis. A must pH below 3.2 in a summer harvest impairs bacterial growth, and the association of low pH with a free-SO2 concentration above 10 mg L-1 may inhibit MLF. For grapes with a high sugar content, harvested in the winter cycle, enologists should keep the alcohol content below 15% and control the alcoholic-fermentation temperature.

Phenolic composition and varietal discrimination of Montenegrin red wines (Vitis vinifera var. Vranac, Kratošija, and Cabernet Sauvignon)

The present work intends to study, for the first time, the characterization of the phenolic composition (hydroxycinnamic and hydroxybenzoic acids derivatives, stilbenes, anthocyanins, and flavan-3-ols) of Montenegrin autochthonous varietal wines Vranac, Kratosija, and an international recognized variety, Cabernet Sauvignon, from different locations of Montenegro, under the same conditions and enological practices by applying chromatographic techniques. The studied varietal wines showed specific varietal profiles for the examined phenolic groups: relative proportion of hydroxycinnamic acids, composition of stilbenes, anthocyanin profile, flavan-3-ols composition of monomers and dimers, as well as some certain wine varietal ratios, namely acetylated/p-coumarylated anthocyanins and trans-coutaric/trans-caftaric acid. Principal component analyses confirmed a separation according to varietal wines. A linear discriminant analysis proved the discriminant power of the phenolic profile to authenticate wine varieties. Vranac wines contained the highest content of anthocyanins. Kratosija wines had the highest content of hydroxycinnamic acids. Cabernet Sauvignon wines contained the highest content of flavan-3-ols and the lowest content of stilbenes. All wines showed high antioxidant activity.

Extended Maceration and Cap Management Impacts on the Phenolic, Volatile, and Sensory Profiles of Merlot Wine

The present study aimed to evaluate the sensory and chemical effects of nine cap management and maceration techniques. Extended maceration (EM) was applied to Vitis vinifera L. cv. Merlot for 0, 1, 2, 4, 6, and 8 wks. In addition, a punch-down treatment and two submerged-cap treatments were also evaluated, giving a total of nine treatments. Descriptive analysis, polyphenolic measures, basic wine parameters, and volatile compound analysis were used to describe these nine treatments. EM defined the astringent texture of the resulting wines, while cap management modified the bitter taste and pepper spice aroma. In total, 27 of 29 measured volatile compounds exhibited a significant treatment effect, thus demonstrating the importance of these enological practices on the final volatile profile. Correlation with EM length was shown for 15 of the significant volatile compounds. In particular, the ester profile of the wines displayed decreased variability after 2 wks of maceration. The results of this study suggest that EM may not be as impactful on astringency as previously thought, due to the fact that EM only significantly affected this attribute after 6 wks. Additionally, the results of the cap management treatments indicated that bitterness can be modified by punch-down versus pump-over techniques.