Enological Suitability of Indigenous Yeast Strains for 'Verdejo' Wine Production.

The use of indigenous yeasts for the production of wines is a tool to defend the typicity of a particular region. The selection of appropriate indigenous yeasts ensures the maintenance of oenological characteristics by simulating spontaneous alcoholic fermentation (AF) while avoiding the risks of stuck or sluggish fermentations. In this study, autochthonous yeasts from Verdejo grape juice (Appellation of Origin Rueda) were selected, identified, and characterized to exploit the characteristics of the 'terroir'. The fermentation capacity of seven strains was studied individually at the laboratory scale. The most suitable strains (Saccharomyces cerevisiae: Sacch 1, Sacch 2, Sacch 4, and Sacch 6) and Sacch 6 co-inoculated with Metschnikowia pulcherrima were characterized at the pilot scale. The fermentation kinetics, bioproduct release, volatile composition, and sensory profile of the wines were evaluated. Significant differences were found, especially in the aroma profile. In particular, Sacch 6 and Sacch 6 co-inoculated with M. pulcherrima produced higher amounts of ethyl esters and acetates and lower amounts of higher alcohols than the spontaneous AF. Wines inoculated with indigenous yeasts had higher sensory scores for fruit aromas and overall rating. The selection of indigenous yeasts improved the aroma of Verdejo wines and could contribute to determining the wine typicity of the wine region.

The Wine Industry By-Products: Applications for Food Industry and Health Benefits.

Each year, 20 million tons of wine by-products are generated, corresponding to 30% of the total quantity of vinified grapes. Wine by-products are a source of healthy bioactive molecules, such as polyphenols and other molecules (pigments, fibers, minerals, etc.). The abundance of bioactive compounds assures a promising future for nutritional foodstuff production. Wine by-products can be used to fortify aromatized waters and infusions, bread, pasta, dairy products, alcohol, sugary beverages, and processed foods. These innovative products are part of the Mediterranean diet and are of great interest to both human and environmental health. Pre-clinical studies show that consumption of food produced with wine by-products or with their extracts attenuates the inflammatory state and increases antioxidant status. As such, wine by-products provide protective effects against the underlying pathophysiological hallmarks of some chronic diseases such as atherosclerosis, diabetes, hypertension, obesity, and cancer. However, the poor bioavailability warrants further investigation on how to optimize the efficacy of wine by-products, and more clinical trials are also needed. The scientific evidence has validated the uses of the dietary nature of wine by-products and has helped to promote their use as a functional food to prevent chronic human diseases.

Feasibility study on the use of ATR-FTIR spectroscopy as a tool for the estimation of wine polysaccharides.

Polysaccharides are the main macromolecules of colloidal nature in wines. These compounds play a critical role in stabilizing other molecules in solution and thus modifying the wine processing and organoleptic properties. Different analytical techniques have been proposed for their determination. However, most of them are complicated and time-consuming. To overcome these drawbacks, Fourier transform infrared spectroscopy (FTIR) has been evaluated in this study for the estimation of wine polysaccharides in a fast and non-destructive way. Spectral data have been correlated with wine polysaccharide contents by modified partial least squares regression (MPLS) using different spectral pretreatments. MPLS models developed have revealed the potential of FTIR analysis for the routine screening of polysaccharides rich in arabinose and galactose (PRAG), rhamnogalacturonans types II (RG-II), mannoproteins (MP) and total soluble polysaccharides (TSP) in wine samples, obtaining standard errors of prediction from 6.07 to 8.44%. Monitoring the wine polysaccharides can assist in the elaboration of the wines according to their requirements and improving quality to satisfy consumer preferences.

Characterization on the impact of different clarifiers on the white wine colloids using Asymmetrical Flow Field-Flow Fractionation.

Clarifiers are substances used during the winemaking process to enhance clarity and stability in the wines. The different clarifiers may alter removal capacities differently. In this study, the removal efficiency of seven common fining agents, divided into three groups (mineral clarifiers, synthetic polymeric clarifiers, and vegetable protein clarifiers), was analyzed with Asymmetrical Flow Field-Flow fractionation (AF4). Besides, the relationship between the removal capacity and different molecular and macromolecular properties has been evaluated. The results showed extensive removal of colloidal and macromolecular matter by the bentonites with potential impact on characteristic properties of the wine. The vegetable clarifiers showed a more profiled reduction, potentially preserving characteristics of the wine. The synthetic polymers showed a more limited removal efficiency but with a high affinity to remove colloidal phenols. The use of AF4-UV-MALS-dRI allowed the characterization of the wines after different clarification treatments, showing to be an analytical technique with a potential impact on the wine industry.

Fractionation of Nanoparticle Matter in Red Wines Using Asymmetrical Flow Field-Flow Fractionation.

The particle matter of wine is mainly composed of wine colloids and macromolecules. The present work develops a methodology using asymmetrical flow field-flow fractionation coupled with multi-angle light scattering, differential refractive index detector, and ultraviolet detector (AsFlFFF-MALS-dRI-UV) for the fractionation and determination of the molar mass, the hydrodynamic radius, and the apparent densities of the aggregates and macromolecules present in wine samples. The results from a set of six Argentinian high-altitude wines showed two main populations: the first population composed of wine colloids with higher UV-specific absorptivity and the second population composed of polysaccharides, such as arabinogalactans. The conformation results showed that population 1 consists of small and dense particles, while population 2 showed high molar masses and lower densities. The results demonstrated the use of AsFlFFF as a new, effective method for the fractionation and characterization of wine colloids and wine macromolecules in red wines with further potential applications.

White wine processing by UHPH without SO2. Elimination of microbial populations and effect in oxidative enzymes, colloidal stability and sensory quality.

The use of UHPH sterilization in the absence of SO2 has been used to eliminate wild microorganisms and inactivate oxidative enzymes. A white must of the Muscat of Alexandria grape variety was continuously processed by UHPH at 300 MPa (inlet temperature: 23-25 °C). The initial microbial load of the settled must was 4-log CFU/mL for both yeast and moulds, and slightly lower for bacteria. After UHPH processing, no microorganisms were detected in 1 mL. UHPH musts remain without fermentative activity for more than 60 days. Concentrations of the thermal markers indicated the absence of thermal damage in the UHPH-treated musts, since 5-hydroxymethylfurfural was not detected. In addition, the must treated by UHPH keeps terpene concentrations similar to those of the untreated controls. A strong inactivation of the oxidative enzymes was observed, with no browning at room temperature for more than 3 days. The antioxidant value of the UHPH-treated must was 156% higher than the control.

Aromatic Potential and Bioactivity of Cork Stoppers and Cork By-Products.

The characterization of natural waste sources is the first step on the reutilization process, circular economy, and global sustainability. In this work, the aromatic composition and bioactive compounds related to beneficial health effects from cork stoppers and cork by-products were assessed in order to add value to these wastes. Twenty-three aromatic compounds with industrial interest were quantified by gas chromatography coupled mass spectrometry GC-MS in both samples. Vanillins and volatile phenols were the most abundant aromatic families. Other aromatic compounds, such as aldehydes, lactones, terpenols, and alcohols, were also determined. Furthermore, the phenolic composition and the antioxidant activity were also evaluated. Overall, extracts showed high aromatic and antioxidant potential to be further used in different industrial fields. The recovery of these valuable compounds from cork stoppers and cork by-products helps to reuse them in agricultural, cosmetic, pharmaceutical, or food industries.

Monitoring the effects and side-effects on wine colour and flavonoid composition of the combined post-fermentative additions of seeds and mannoproteins.

One of the main consequences of the advancement of harvest date associated to global climate change is that the phenolic maturity of grapes can be delayed in relation to their technological maturity. As a consequence, wines made from these grapes can be poor in phenolic compounds or possess an unbalanced phenolic composition, affecting their global quality. The combined post-fermentative addition of seeds and an astringency-modulator mannoprotein (MP) might be a potential strategy to solve this problem, since seeds might supply flavanols and improve wine chemical stability and the mannoprotein might modulate the changes induced in astringency by the addition of seeds and improve wine colloidal stability. The present study aimed at monitoring at different moments of winemaking and ageing the effects and side-effects of this combined strategy on the detailed flavanol, flavonol and anthocyanin compositions and on colour of wines made from Syrah grapes. Seeds were obtained from Pedro Ximénez overripe grapes. Flavanol composition and flavonol and anthocyanin compositions were determined by HPLC-MSn-MRM and HPLC-DAD-MSn analyses, respectively. Colour changes caused by these additions were studied from CIELAB parameters as well as the ability of these techniques to protect colour from bleaching agents, such as SO2. In general, the addition of seeds initially increased the levels of flavanols and anthocyanins. However, during bottle ageing a reduction in the levels of flavanols, flavonols and anthocyanins could be observed in seed treated wines, which might be related to the greater formation of flavanol aggregates associated with greater levels of flavanols. This effect was partially solved for most of the flavonoids studied with the additional MP treatment. Treated and control wines showed colour differences that were visible to human eye, although they were reduced over time. At the end of the study, treated wines showed colour parameters corresponding to younger wines than those observed in control wines. A greater resistance against SO2 bleaching was also observed in treated wines, which can be mainly associated to the greater percentages of polymeric pigments caused by seed treatment and to the improvement of the colloidal stability of SO2-resistant pigments caused by the addition of the MP.

Effects of fertigation by elicitors enriched in amino acids from vegetal and animal origins on Syrah plant gas exchange and grape quality.

Nutrition management of vines is a key factor that regulates production and determines grape quality. Currently, one of the main objectives of fertilization is to apply eco-friendly and balanced nutrition. In this case, fertigation is the most efficient strategy. The objective of this work was to assess the effect of innovative fertilizers on Syrah grapevines. The tested products contained an elicitor, macro- and microelements and amino acids from animal and vegetal origins. Fertilizers were applied by fertigation under field conditions in 2016, 2017 and 2018. The influence of the treatments on the grapevine gas exchange, element assimilation and oenological composition of must was evaluated. Additionally, the amino acid contents and volatile composition were determined. The results suggest that application of fertigation does not directly influence the water status of Syrah vines under the conditions of the study but can improve the gas exchange balance and N assimilation. Moreover, the leaf assimilation of Zn, Ca and, to a lesser extent, B were improved at the bloom stage, and the assimilation of Mn was improved at veraison. Small changes were observed in the basic parameters of musts, and an increase in yeast assimilable nitrogen was detected in treated vines. The aromatic profile of grape musts was enhanced in treated vines, and the elicitors enriched in vegetal amino acids could be a sustainable alternative for improving certain vegetative and grape quality parameters of Syrah.

Specific profile of Tempranillo grapevines related to Esca-leaf symptoms and climate conditions.

Esca is a destructive fungal disease affecting grapevines worldwide. In the Esca complex, grapevine leaf stripe disease (GLSD) designates specifically the disease that causes the typical leaf symptoms on infected vines. Understanding foliage alterations produced by GLSD may help to identify potential markers of tolerance to this disease. In this work, changes related to physiological parameters, photosynthetic pigments and phenolic compounds were evaluated. Moreover, the expression of 10 genes was tracked determined by quantitative reverse transcription-PCR. For this, symptomatic and asymptomatic vines from three different Tempranillo vineyards were evaluated. Vineyards differed in climate classification and water resources. Botryosphaeriaceae species and Esca causal agents (Phaeomoniella chlamydospora, Phaeoacremonium spp. and Fomitiporia mediterranea) were isolated and identified from symptomatic vines. Under water restriction, a significant decrease on the physiological activity of symptomatic vines was observed. Also, symptomatic leaves showed lower content on chlorophylls and carotenoids and some alterations on their phenolic profiles. GLSD symptoms induced the expression of defense-related genes, especially PR6, STS and Chit 1b. This research provides valuable information regarding physiological, chemical and molecular changes in Esca affected leaves of Tempranillo grown in vineyards related to the climate conditions.

Evaluation of Tempranillo and Albariño SO2-free wines produced by different chemical alternatives and winemaking procedures.

In this work physical and chemical alternatives to produce SO2 free wines are shown. The use of inactive yeast strains enriched in glutathione, chitosan, dimethyldicarbonate and different hydrolysable and condensed tannins were assessed in Tempranillo and Albariño wines. The time of addition, mixtures of additives and the use of inert gases were evaluated. In general, no significant differences on the sensory quality were shown when compared sulphited and non-sulphited wines. Both physical and chemical treatments were more effective for Tempranillo wines. In the two studied vintages, non-sulphited Tempranillo wines were better valuated than controls, even when wines were produced only using the application of inert gases. No differences were observed when argon was used instead of carbon dioxide as inert gas. Mixtures of seed and skin tannins with inactive dry yeast enriched in glutathione were the most effective treatments. This work may help winemakers to elaborate healthier wines meeting the current consumer demands.

Interaction between Wine Phenolic Acids and Salivary Proteins by Saturation-Transfer Difference Nuclear Magnetic Resonance Spectroscopy (STD-NMR) and Molecular Dynamics Simulations.

The interaction between phenolic compounds and salivary proteins is highly related to the astringency perception. Recently, it has been proven the existence of synergisms on the perceived astringency when phenolic acids were tested as mixtures in comparison to individual compounds, maintaining constant the total amount of the stimulus. The interactions between wine phenolic acids and the peptide fragment IB712 have been studied by saturation-transfer difference (STD) NMR spectroscopy. This technique provided the dissociation constants and the percentage of interaction between both individual and mixtures of hydroxybenzoic and hydroxycinnamic acids and the model peptide. It is noteworthy that hydroxybenzoic acids showed higher affinity for the peptide than hydroxycinnamic acids. To obtain further insights into the mechanisms of interaction, molecular dynamics simulations have been performed. Results obtained not only showed the ability of these compounds to interact with salivary proteins but also may justify the synergistic effect observed in previous sensory studies.

Effect of flavonols on wine astringency and their interaction with human saliva.

The addition of external phenolic compounds to wines in order to improve their sensory quality is an established winemaking practice. This study was aimed at evaluating the effect of the addition of quercetin 3-O-glucoside on the astringency and bitterness of wines. Sensory results showed that the addition of this flavonol to wines results in an increase in astringency and bitterness. Additionally, flavonol-human salivary protein interactions were studied using fluorescence spectroscopy, dynamic light scattering and molecular dynamic simulations (MD). The apparent Stern-Volmer (KsvApp) and the apparent bimolecular quenching constants (kqApp) were calculated from fluorescence spectra. The KsvApp was 12620±390M(-1), and the apparent biomolecular constant was 3.94×10(12)M(-1)s(-1), which suggests that a complex was formed between the human salivary proteins and quercetin 3-O-glucoside. MD simulations showed that the quercetin 3-O-glucoside molecules have the ability to bind to the IB937 model peptide.

New Anthocyanin-Human Salivary Protein Complexes.

The interaction between phenolic compounds and salivary proteins is considered the basis of the poorly understood phenomenon of astringency. Furthermore, this interaction is an important factor in relation to their bioavailability. In this work, interactions between anthocyanin and human salivary protein fraction were studied by mass spectrometry (MALDI-TOF-MS and FIA-ESI-MS) and saturation-transfer difference (STD) NMR spectroscopy. Anthocyanins were able to interact with saliva proteins. The dissociation constant (KD) between malvidin 3-glucoside and salivary proline-rich proteins was 1.92 mM for the hemiketal form (pH 3.4) and 1.83 mM for the flavylium cation (pH 1.0). New soluble complexes between these salivary proteins and malvidin 3-glucoside were identified for the first time.

Characterization of Sensory Properties of Flavanols - A Molecular Dynamic Approach.

In this work, sensations elicited by catechin and procyanidins in comparison with those elicited by gallocatechin and prodelphinidins were evaluated by means of a sensory panel. To obtain further insights into the mechanisms of action, molecular dynamics (MD) simulations and saturation transfer difference nuclear magnetic resonance (STD NMR) experiments have been performed. Results showed clear differences between the 2 types of flavanols. Dihydroxylated B-ring flavanols were more astringent, bitter, dry, rough, unripe, and persistent than trihydroxylated B-ring ones. Besides, these last compounds were smoother, more velvety, and viscous. MD simulations and STD NMR experiments support results obtained from tasting panel. MD results suggested that catechin binds to a human salivary proline-rich peptide IB714 faster than gallocatechin and this interaction is maintained longer. IB714 can interact with 2 catechin molecules concurrently while only interacts with 1 gallocatechin molecule. Accordingly, STD NMR experiments showed a greater affinity of catechin than gallocatechin for the peptide (K D = 2.7 and 25.7, respectively). Results indicate that the number of hydroxyl substituents present in B-ring of the flavanic nucleus is decisive for the interaction with salivary proteins and the development of astringency perception.

A comparative study to distinguish the vineyard of origin by NIRS using entire grapes, skins and seeds.

BACKGROUND: Interest in high-quality products with a clear geographical origin is increasing. For the wine industry and market sector, identity preservation is of fundamental importance owing to the large number of geographical classifications. Nowadays, there is a growing demand for analytical methods for tracing grapes and wines. In the oenological sector, infrared spectroscopy is becoming an attractive tool allowing simultaneous measurement of several analytical parameters and enabling real-time decision making. RESULTS: Discriminant partial least squares, a supervised pattern recognition technique, was employed to discriminate between vineyards of origin using the near-infrared spectra of intact grapes, skins or seeds. In order to compare the three sample presentations, a receiver operating characteristic curve was used. The best results were obtained using intact grape seeds, with prediction rates of samples correctly classified of about 95%, although the good results obtained with entire grapes (about 93% of samples correctly classified) and the simplicity of use of the fibre optic probe could advise using entire grape presentation for comprehensive studies. CONCLUSION: The procedure reported here seems to have excellent potential for a fast and reasonably inexpensive analysis of the origin of samples. It is noted that such classification can be made at any time of ripening. This paper provides information of interest to develop new and extensive models in the future.

Interaction of phenolic compounds with bovine serum albumin (BSA) and α-amylase and their relationship to astringency perception.

The ability of grape seed extracts to bind to bovine serum albumin (BSA) and α-amylase was studied by fluorescence quenching of protein intrinsic fluorescence and nephelometry. The influence of grape seed ripeness on astringency was also evaluated. From the spectra obtained, the modified Sterm-Volmer (K(app)) and the bimolecular quenching constants were calculated. Results showed that grape seed extracts had good affinity for proteins. The association strength of tannin-protein interactions varied with changes in tannin structure associated with the degree of ripeness affecting the binding/quenching process. In all cases studied, higher values of K(app) were obtained in samples at harvest which have greater ability to bind to proteins than have samples at post-veraison time. Nephelometric assays show the same trend as do fluorescence quenching studies. A possible explanation for this is that, as seeds ripen, their tannins increase in molecular mass, which relates to an increase in hydrophobicity of the molecules, and this increases protein affinity. However, that is contrary to the reported decrease in astringency of grape seeds during maturity. This indicates that tannin-protein interactions are not the only explanation for the complex sensations of astringency of grape seeds.

Influence of climatic conditions on the phenolic composition of Vitis vinifera L. cv. Graciano.

The influence of different climatic conditions on the phenolic composition of grape skins and seeds of Vitis vinifera L. cv. Graciano - an autochthonous cultivar from Rioja and Navarra regions (Spain) - was evaluated during ripening in a separate way. Graciano grapes from two different vineyards with different climatic conditions and from two different vintages (2008 and 2009) were analysed. Clear differences between phenolic maturity pattern of grape skins and seeds were observed. In this context, it may be important to evaluate the phenolic maturity of seeds and skins in a separate way in order to decide the optimal harvest time. It was also noticeable that the effect of vintage (mainly due to changes in climatic conditions) may affect the changes in the phenolic composition of both grape skins and seeds. Although in a lesser extent, the effect of the vineyard was also observable, and it was especially relevant in vintages with irregular climatic conditions such as 2008 vintage. In a second strand, results obtained from the phenolic composition of grape seeds and skins at harvest, oenological parameters at harvest and climate conditions during vegetative stage were evaluated and relationships among the aforementioned variables were revealed.

Preliminary study to determine the phenolic maturity stage of grape seeds by computer vision.

The applications of computer vision technology for acquiring and analysing images have been extended to the quality evaluation in food industry. This technique involves great advantages for the objective, rapid, non-contact and automated quality inspection and control. The aim of this work was to evaluate the potential of the computer vision to determine the phenolic maturity stage of grape seeds. Up to 21 phenolic compounds were determined by HPLC-DAD-MS in order to obtain reference values to develop the model. The CIELAB parameters, area, aspect, roundness, length, width and heterogeneity of seeds were analysed using a DigiEye(®) system. The technique reported in this work can be a good and rapid tool for taking decisions at harvest time. Notwithstanding, a comprehensive study should be made in order to develop more robust models.

Feasibility study on the use of near infrared spectroscopy to determine flavanols in grape seeds.

The potential of near infrared spectroscopy to determine the content of flavanols directly recording the infrared spectra of grape seeds has been evaluated. Moreover, the study shows the potential of this technique to obtain qualitative information related to the samples. In this case, the feasibility to discriminate between possible vineyards of origin has also been evaluated. Modified Partial Least Squares (MPLS) regression was used to develop the quantitative models in order to predict the content of flavanols. These models have been validated showing differences between 3.5% and 14.3% in the external validation. Moreover, Discriminant Partial Least Squares algorithm was used in the qualitative analysis to distinguish between two possible vineyards of origin and showed a high degree of accuracy. Prediction rates of samples correctly classified with a mean of 95% in internal validation and 97% in external validation were obtained. The procedure reported here seems to have an excellent potential for a fast and reasonably inexpensive analysis of these flavanols in grape seeds and could also be a tool to distinguish between possible vineyards of origin.