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Copper-sulfhydryl complexes in wine can be disrupted by addition of brine to release free hydrogen sulfide (H2S), and the resulting "brine-releasable H2S" is reported to correlate with formation of H2S during bottle storage. However, both the mechanism of the brine-release assay and factors affecting the stability of copper sulfhydryls under brine-release conditions are not well understood. By varying brine composition and concentration, it is shown that release of copper-complexed H2S requires the presence of a halide (Cl- and Br-) and is not due to a general "salting-out" effect. Release of copper-complexed H2S by the brine dilution assay is highly temperature-dependent. When H2S and Cu(II) are added to a model wine, brine-releasable H2S decreases markedly (∼10-fold) after a 20 min incubation period prior to performing the brine-release assay. In commercial wines, the fraction of added H2S recovered through the brine-release assay was correlated with the initial glutathione (GSH) concentration (r2 = 0.58) but not with initial Cu. Negligible additional release of H2S from organopolysulfanes was observed following addition of a disulfide-reducing agent (tris(2-carboxyethyl)phosphine). As previous studies have reported a correlation between H2S formed under brine-release conditions and normal storage, these results suggest that the susceptibility of a wine to form latent copper-sulfhydryl precursors of H2S following copper addition is dependent on the concentration of sulfhydryls like GSH.

Sensorial studies on pinked white wines have never been carried out. The aim of this study was to establishthe probability of an aroma and taste difference in pinked Sauvignon blanc wines using a triangular test.The issue of at which point a wine consumer can perceived the wine as pink was analysed using a rankingexperiment. The probability that a wine taster can detect oxidised and pink wines as a wine fault was alsoanalysed. It was found that the panellists could not detect anomaly samples by taste and aroma alone,although some noticed an oxidised aroma on the nose. The pink detection point was established at 0.03 AU.This point can be used to refine the detection point and the assay used. It was established that more than50% of the panellists could detect oxidised and pink wines as a wine fault. The study data can be used toeither train panellists to detect pinking as a wine fault, or to establish a potential new category for pinkSauvignon blanc wines.

While there have been numerous studies on individual wine faults and their risk factors little is known about their incidence and overall relationship to risk factors when purchased. To assess this relationship 100 wines produced in Missouri were randomly selected from the approximately 2500 available for sale in 2015- 2016. The wines collected went under a battery of tests for selected wine faults, flaws and known risk factors for problem development. The physical assessments included in this study where visual faults such as haze, sediment, excess turbidity and fill height from top of the bottle. Volatile compounds related to Brettanomyces sp. infection and cork taint were quantified as well as the undesirable aromas compounds H2S and 1-octen-3-ol, and acetic acid. Additional risk factors for fault development such as low free SO[subscript 2], high pH (above pH 3.7) and residual sugar were also assessed. Tested risk factors have varied greatly with wines having a pH value from 2.97-4.11, and free and total SO[subscript 2] varying from 0-118 mg/L and 3.6-324.4 mg/L respectively. While none of the wines exceeded current US legal limits for SO[subscript 2], 6% ([plus or minus]15%, for all MO wines at 95% CI) exceeded EU limits for total SO[subscript 2]. Conversely, 84% of the wines did not meet the free SO[subscript 2] requirement of 0.8 ppm based upon pH. At a fault recognition >|10|[micro]g/L for H[subscript 2]S 23% of the wines exceeded acceptable levels being considered faulted with no significant differences between categorical variables (e.g. red or white wine, closure type, fill volume etc.). This study is only one small sub-set of one region; to best understand how this data fits in with the wine industry as a whole, additional surveys are warranted. However, there is no reason to believe that this region is any different than would be found elsewhere.

Hydrogen sulfide is a common wine fault, with a rotten-egg odour, which is directly related to yeast metabolism in response to nitrogen and sulfur availability. In grape juice, sulfate is the most abundant inorganic sulfur compound, which is taken up by yeast through two high-affinity sulfate transporters, Sul1p and Sul2p, and a low affinity transporter, Soa1p. Sulfate contributes to H2 S production under nitrogen limitation, by being reduced via the Sulfur Assimilation Pathway (SAP). Therefore, yeast strains with limited H2 S are highly desirable. We report on the use of toxic analogues of sulfate following ethyl methane sulfate treatment, to isolate six wine yeast mutants that produce no or reduced H2 S and SO2 during fermentation in synthetic and natural juice. Four amino acid substitutions (A99V, G380R, N588K and E856K) in Sul1p were found in all strains except D25-1 which had heterozygous alleles. Two changes were also identified in Sul2p (L268S and A470T). The Sul1p (G380R) and Sul2p (A470T) mutations were chosen for further investigation as these residues are conserved amongst SLC26 membrane proteins (including sulfate permeases). The mutations were introduced into EC1118 using Crispr cas9 technology and shown to reduce accumulation of H2 S and do not result in increased SO2 production during fermentation of model medium (chemically defined grape juice) or Riesling juice. The Sul1p (G380R) and Sul2p (A470T) mutations are newly reported as causal mutations. Our findings contribute to knowledge of the genetic basis of H2 S production as well as the potential use of these strains for winemaking and in yeast breeding programmes.

More than hundreds of private wineries have been established since the Taiwan Tobacco and Alcohol Administration Act was enacted on April 19, 2000. It is then essential to screen local wine yeast in order to develop quality wine with unique flavor. Black Queen grape is a main ingredient for red wine brewing in Taiwan. In this study, ethanol productivity of yeasts isolated from spontaneous fermentation of Black Queen grape must (17 and 30 °Brix) was determined. Seven yeasts identified as Saccharomyces cerevisiae by Biolog System with higher ethanol productivity were individually inoculated into Black Queen grape must to undergo fermentation at 25℃ for 14 days. The ethanol contents and volatile acidity in wine were above 15% (v/v) and below 0.7 g/L, respectively. Compared to commercial wine yeasts A, B and C, HP01 fermented red wine contained the highest total ester content, color intensity, taste grade, and overall preference value. On the other hand, HS13 fermented red wine contained the highest ethanol, higher alcohols, fatty acids and phenolic compounds content. The mtDNA restriction fragments profiles of these two wine yeast strains were different from those of other yeast strains. Due to their superiority in oenological characteristics, HP01 and HS13 can be applied in Black Queen red wine brewing to produce red wine with unique flavor.

High quality sparkling wine made by the traditional method requires a second alcoholic fermentation of a base wine in sealed bottles, followed by an aging time in contact with yeast lees. The CO2 overpressure released during this second fermentation has an important effect on the yeast metabolism and therefore on the wine aroma composition. This study focuses on the changes in chemical composition and 43 aroma compounds released by yeast during this fermentation carried out under two pressure conditions. The data were subjected to statistical analysis allowing differentiating between the base wine and the wine samples taken in the middle and at the end of fermentation. The differentiation among wines obtained to the end of fermentation with or without CO2 pressure is only achieved by a principal component analysis of 15 selected minor compounds (mainly ethyl dodecanoate, ethyl tetradecanoate, hexyl acetate, ethyl butanoate and ethyl isobutanoate).

The level of hydrogen sulfide (H2S) can increase during abiotic storage of wines, and potential latent sources of H2S are still under investigation. We demonstrate that elemental sulfur (S0) residues on grapes not only can produce H2S during fermentation but also can form precursors capable of generating additional H2S after bottle storage for 3 months. H2S could be released from S0-derived precursors by addition of a reducing agent (TCEP), but not by addition of strong brine to induce release of H2S from metal sulfide complexes. The size of the TCEP-releasable pool varied among yeast strains. Using the TCEP assay, multiple polar S0-derived precursors were detected following normal-phase preparative chromatography. Using reversed-phase liquid chromatography and high-resolution mass spectrometry, we detected an increase in the levels of diglutathione trisulfane (GSSSG) and glutathione disulfide (GSSG) in S0-fermented red wine and an increase in the levels of glutathione S-sulfonate (GSSO3-) and tetrathionate (S4O62-) in S0-fermented white wine as compared to controls. GSSSG, but not S4O62-, was shown to evolve H2S in the presence of TCEP. Pathways for the formation of GSSSG, GSSG, GSSO3-, and S4O62- from S0 are proposed.

Antioxidant properties and flavor characteristic profile of pomegranate wine during winemaking were investigated. The total phenol content and radical scavenging activity exhibited a slightly decrease in the end edge. Punicalagins and gallic acid were revealed to be the most abundant phenolic compounds, followed by ellagic acid and vanillic acid. These constituents were mainly responsible for the effective antioxidant capacity of pomegranate wine. The major changes of flavor qualities occurred in the initial stage, particularly 0-4day of fermentation. Fermentation significantly reduced the relative content of aldehydes, ketones, heterocyclic and aromatic compounds, but promoted the generation of esters and alcohols. This is the first time of using E-nose and E-tongue to monitor odour and taste changes in the brewing process of pomegranate wine. The study may provide a promising instruction for improving functional features and quality control of the pomegranate wine.

The grape used in wine making has many wild microorganisms like lactic acid bacteria, yeast, acetic acid bacteria. During the alcoholic fermentation, the evaluation of these microorganisms depends on their activity. There is an interaction between yeast and lactic acid bacteria during this period of wine making. In this study, we have made wine from the autochthonous Albanian grape Kallmet variety using the spontaneous fermentation and inoculated fermentation with the yeast Saccharomyces bayannus. Yeasts carry out the alcohol fermentation, and lactic acid bacteria make malolactic fermentation in wine. With this fermentation, lactic acid bacteria convert malic acid to lactic acid, reducing the acidity of the wine and create a microbiological stability. During the alcoholic fermentation, the evaluation of lactic acid bacteria is not required. The aim of our study is to evaluate the first quantity of lactic acid bacteria to Kallmet grape, their performance during the two fermentations, spontaneous and inoculated fermentations.

The aim of the present study is to highlight volatile and targeted non-volatile bioactive compounds in Nuragus wines, as a part of Italian DOC (Controlled Origin Designation) white wines. So far there has not been any systematic study of the chemical compositions and antioxidant activity of this monovarietal wine. Phenolic compounds, volatiles and organic acids were analysed and antioxidant capacity was assessed by spectrophotometric assays. Chromaticity coordinates and technological parameters (alcohol, reducing sugars, pH, total and volatile acidity) were also evaluated. Gallic acid (128 ± 87 mg/L), trans-caftaric acid (81 ± 27 mg/L) and tyrosol (25 ± 8 mg/L) were the most abundant phenolic compounds. The major headspace volatiles were isoamyl alcohol (35.8–76.6%) and 2-phenylethanol (5.9–24.9%). In the wine extracts, the most abundant were 2-phenylethanol (12.3–40.0%), 4- hydroxy-2-phenylethanol (12.5–33.3%), diethyl succinate (5.8–30.3%), (Z)-octadec-9-en-1-ol (5.9– 18.3%) and tryptophol (2.8–15.6%). Nuragus wines exhibited an excellent antioxidant capacity. The data obtained may help Nuragus wine producers to promote this monovarietal wine as a valid complement associated with the Mediterranean diet.

Winemaking by-products account for more than 30% of the grape production, but this inexpensive feedstock has not yet been fully exploited. Accordingly, we evaluated the potential biological activity of winemaking by-products produced with Syrah grapes in comparison with those of the wine produced using the same grape cultivar. Winemaking by-products showed higher contents of total anthocyanins, flavonols, stilbenes, and flavanols than red wine as evaluated by HPLC-DAD-FD (on a dry weight basis). In contrast, red wine was a better source of phenolic acids. However, the contribution of phenolic acids was minor for both samples. Furthermore, equivalent concentration of winemaking by-products (100 mg/kg/d) showed greater biological activity by than that of red wine by decreasing the levels of VLDL-cholesterol and triacylglycerols in Wistar rats. Therefore, this study supports the use of winemaking by-products as an economical source of bioactive phenolics with potential use in the food and nutraceutical industries.

This work was conducted to identify the major low molecular weight compounds present in the wine precipitate and to assess their potential contribution to wine protein haze formation. The heat-induced protein precipitate from a white Moscatel of Alexandria wine was subjected to alkaline hydrolysis. The major compound present was found to be caffeic acid among other minor, unidentified compounds. Caffeic acid was identified by both UV-vis and 1H NMR spectra. The concentration of caffeic acid in the original wine sample was 1.1mg/L, as quantified by HPLC following SPE. Heat stability tests were performed using two different concentrations of caffeic acid and its ester caftaric acid in model wine solution added of isolated wine protein. No correlation was found between caffeic or caftaric acid concentration and haze forming potential in wine model solution. This work shows that caffeic acid is present in considerable amounts in Moscatel wine protein haze, but does not seem to trigger or participate in the protein aggregation mechanism upon heating.

Background and Aims The light-struck taste is a fault occurring in light-exposed white wine containing methionine and a high concentration of riboflavin (RF) and bottled in clear bottles. These conditions induce the formation of methanethiol and dimethyl disulfide, responsible for a cabbage-like aroma. In order to decrease the risk of wine spoilage, a low concentration of RF should be obtained in wine either by preventing RF release from yeast during winemaking or by removing RF from wine. Methods and Results Fifteen commercial Saccharomyces strains intended for the wine industry were tested for RF production, which was also evaluated when two yeast-based nutrients were added into the must for one of these strains. The RF released during vinification was strain-dependent and a concentration from 30 to 170 μg/L was found in wine. A high concentration of RF was released in the presence of the yeast-based nutrients because of either the yeast metabolism or the RF contained in the nutrient itself. The ability of different inorganic (bentonite, charcoal, zeolite, kaolin) and organic adjuvants (egg-white proteins, polyvinylpolypyrrolidone) to deplete RF in wine was evaluated. A relatively low level of charcoal (50 mg/L) removed up to 60% of RF in wine, although its effectiveness was related to the charcoal source. A high concentration of bentonite (1 g/L) was needed to effectively decrease the risk of wine spoilage. Conclusions A critical RF concentration in white wine can be prevented by applying one or more approaches in winemaking: using low RF-producing yeast strains in fermentation, selecting suitable yeast nutrients or adsorbing RF by insoluble charcoal or bentonite. Significance of the Study The research highlights suitable tools to prevent light-struck taste in white winemaking.

The study investigated 15 variants of wine differing in their must pre-treatment (maceration by enzymes: Siha Pectinase or SihazymUni) and fermentation by different yeast strains (S.cerevisiae as ICV - D-47; SIHA- Cryaroma; Challenge Aroma White; and S. bayanus as SIHA Active Yeast). The effects of experimental conditions on chemical composition (pH, acidity, sugar), content of phenolic (LC–PDA-QTOF/MS) and volatile compounds (GC-MS), antioxidant activity (ABTS and FRAP assay), color property (CIEL*a*b*), and ethanol content were measured. For all production processes, significant changes in basic parameters and in the amount of polyphenolic compounds and antioxidant activity in wine were observed as compared to must. The wines obtained with S. cerevisiae were characterized by higher polyphenol content, smaller reduction of antioxidant activity and the strongest aroma. Challenge Aroma White yeast strain particularly contributed to good quality of wine. Enzymatic pre-treatment did not significantly affect the studied parameters (expect pH and the content of phenolic acids).

The aim of this study was to evaluate the efficiency of malolactic fermentation in the production of red and white wine from high-acid musts (up to 9.5 g/L malic acid), typical for cool-climate European wine zones. Four vinification scenarios were investigated: alcoholic fermentation only, simultaneous malolactic and alcoholic fermentation, malolactic fermentation induced at the end of alcoholic fermentation, and spontaneous malolactic fermentation. Our results, confirmed in three independent wine seasons, indicate that the best results, expressed as the greatest dynamics and efficiency in the deacidification, were observed when alcoholic and malolactic fermentation was simultaneous (83.97–94.84% reduction in malic acid). A total reduction in malic acid in such acid musts was not possible. In the co-inoculation scenario, fermentation time was significantly reduced, there was no increase in volatile acidity, and the lowest residual sugar concentrations were noted. Advantageously, the timing of the malolactic bacteria inoculation had no effect on the metabolism of such secondary metabolites as citric and acetic acids as well as on the final ethanol and glycerol concentration. It was suggest that co-inoculation of yeast and bacteria can be a very useful technique in the process of cool-climate grape wine production and also can be regarded as being applicable on industrial scale specially for very high-acid grape must.

The volatile compounds of Chinese rice wine fermented by Saccharomyces cerevisiae FC 15 and S. cerevisiae BR 30 and their combination (MIX) were investigated. The results showed that the wines fermented with different starters differed mainly in the numbers of alcohols and esters. Furthermore, the amounts of volatile compounds among three starters were also obviously different. After clarification, the loss of esters was greater than that of alcohols and aldehydes, whereas after sterilization, the loss of aldehydes was the greatest. PCA showed diethyl succinate to be the key flavor component. Moreover, short-chain fatty acid ethyl esters were main flavor substances during fermentation, whereas long-chain fatty acid ethyl esters were typical compounds after clarification and sterilization. Analysis of the ratio of higher alcohols to esters showed that BR 30 wine presented a stronger ester aroma than MIX wine, whereas FC 15 wine exhibited an outstanding alcohol flavor. Sensory evaluation indicated that FC 15 wine was intense in alcohol-aroma, whereas BR 30 wine exhibited high levels of cereal-aroma. Furthermore, both MIX and BR 30 wine were highly assessed in continuation and full body mouth-feel. It means that flavor characteristic of Chinese rice wine could be adjust by combination of yeast starters.

The typical fruity aroma of red Bordeaux wines depends on the grape variety but also on microbiological processes, such as alcoholic and malolactic fermentations. These transformations involve respectively the yeast Saccharomyces cerevisiae and the lactic acid bacterium Oenococcus oeni. Both species play a central role in red winemaking but their quantitative and qualitative contribution to the revelation of the organoleptic qualities of wine has not yet been fully described. The aim of this study was to elucidate the influence of sequential inoculation of different yeast and bacteria strains on the aromatic profile of red Bordeaux wine.; Results: All microorganisms completed fermentations and no significant difference was observed between tanks regarding the main oenological parameters until 3 months' aging. Regardless of the yeast strain, B28 bacteria required the shortest period to completely degrade the malic acid, compared to the other strain. Quantification of 73 major components highlighted a specific volatile profile corresponding to each microorganism combination. However, the yeast strain appeared to have a predominant effect on aromatic compound levels, as well as on fruity aroma perception.; Conclusion: Yeasts had a greater impact on wine quality and have more influence on the aromatic style of red wine than bacteria. © 2017 Society of Chemical Industry.; © 2017 Society of Chemical Industry.

Current winemaking trends include low-temperature fermentations and using non-Saccharomyces yeasts as the most promising tools to produce lower alcohol and increased aromatic complexity wines. Here we explored the oenological attributes of a C. sake strain, H14Cs, isolated in the sub-Antarctic region. As expected, the cold sea water yeast strain showed greater cold growth, Na+-toxicity resistance and freeze tolerance than the S. cerevisiae QA23 strain, which we used as a commercial wine yeast control. C. sake H14Cs was found to be more sensitive to ethanol. The fermentation trials of low-sugar content must demonstrated that C. sake H14Cs allowed the cold-induced lag phase of growth to be eliminated and also notably reduced the ethanol (-30%) and glycerol (-50%) content in wine. Instead C. sake produced sorbitol as a compatible osmolyte. Finally, the inspection of the main wine volatile compounds revealed that C. sake produced more higher alcohols than S. cerevisiae. In conclusion, our work evidences that using the Antarctic C. sake H14Cs yeast improves low-temperature must fermentations and has the potential to provide a wine with less ethanol and also particular attributes.

White wines from two vintages were bottled in green and flint glass bottles and stored under typical supermarket shelf conditions. Light-strike fault, colour changes, light and temperature exposure were monitored up to 50 days. In general, green glass bottles secured wine quality for the tested period. Only a few flint glass bottled wines developed a fault due to light-strike after 1–2 days of supermarket shelf life, but all developed the fault after 20–40 days; so we considered the possibility of two mechanisms causing the problem. Flint-glass bottled wines stored on the bottom shelf developed the defect only slightly later compared with the wines on the top shelf. Moreover, storing the wines in dark and cold after a period of exposure to light did not eliminate the fault, indicating that the defect is probably additive. Monitoring the amount of light to which wines are exposed could prevent the fault.

Chemistry is complex physics as life is complex chemistry. How this quantum jump in complexity applies to grapes and wines is the topic of the current chapter. It begins with a basic review of their significant chemical functional groups. This leads into a discussion of: the major organic and inorganic components of grapes and wine; sugars and related simpler carbohydrates; alcohols; organic acids (fixed and volatile); the origins, modification, and significance of phenolics (anthocyanins, non-flavonoids, and tannins); carbonyls (aldehydes and ketones); esters; lactones and other heterocycles; terpenes; nitrogen compounds; thiols and other organosulfur constituents; hydrocarbons and their derivatives; macromolecules (carbohydrates, lipids, proteins, nucleic acids); vitamins; dissolved gases (carbon dioxide, sulfur dioxide, oxygen); and minerals. This is concluded with a discussion of the nature of varietal aromas.

Background and Aims The request by the consumer for safer food is also pushing the wine sector to find alternative solutions to sulfur dioxide. The aim of this research has been to evaluate the application of ozone as a sanitising agent of grapes before vinification in order to avoid the use of sulfur dioxide. Methods and Results Postharvest ozone fumigation overnight of Petit Verdot grapes increased anthocyanin concentration by 19% versus 9% in the Control (untreated) during fermentation/maceration. Fermentation kinetics were faster in wine made from ozone-treated grapes (16 vs 21 days for the Control), and extraction of phenolic substances and anthocyanin was more rapid than that in the Control wines, Ozone treatment significantly reduced the count of Saccharomyces cerevisiae and non-Saccharomyces yeasts but also significantly decreased the acetic acid bacteria. The final wine produced from ozone-treated grapes was characterised by low volatile acidity (similar to that of the Control wine) with a significant reduction in sulfur dioxide (17 and 8 mg/L, respectively, total and free sulfur dioxide). Sensory evaluation revealed a strong fruity aroma. Conclusions Ozone gas treatment of grapes reduced the microbial count significantly and increased the extraction of phenolic substances and the aroma of the final wine. Significance of the Study Postharvest ozone fumigation can be used to produce wine without sulfur dioxide.

The effects of wine phenolic compounds (PCs), hydroxybenzoic acids, hydroxycinnamic acids, and a flavanol, on the growth of Lactobacillus hilgardii and Pediococcus pentosaceus, both isolated from Argentine red wine, were assayed in synthetic winelike medium for the first time. The greatest inhibition of L. hilgardii 6F, L. hilgardii X1B, and P. pentosaceus 12p occurred with 400 mg/L of either trans-caffeic or trans-p-coumaric acid and 96 hr of incubation. P. pentosaceus was the most sensitive to PCs. A structure-antibacterial activity relationship study of the PCs revealed that trans-caffeic and trans-p-coumaric acid have similar electron distributions with interatomic distances of 8 Å between the catechol hydroxyls and the carboxyl group. These minimum structural requirements (pharmacophore pattern) present in the molecule of the phenolic compounds are necessary to produce antibacterial activity against wine spoilage lactic acid bacteria. Fil: Stivala, Maria Gilda. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán; Argentina. Universidad Nacional de Tucumán. Facultad de Bioquímica, Química y Farmacia; Argentina Fil: Villecco, Margarita Beatriz. Universidad Nacional de Tucumán. Facultad de Bioquímica, Química y Farmacia; Argentina Fil: Enriz, Ricardo Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto Multidisciplinario de Investigaciones Biológicas de San Luis. Universidad Nacional de San Luis. Facultad de Ciencias Físico Matemáticas y Naturales. Instituto Multidisciplinario de Investigaciones Biológicas de San Luis; Argentina Fil: Aredes Fernández, Pedro Adrián. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán; Argentina. Universidad Nacional de Tucumán. Facultad de Bioquímica, Química y Farmacia; Argentina

The objective of this study was to investigate quality properties of ‘Cheonghyang’ wine using different commercial yeast strains. Soluble solid content, pH level and total acidity of ‘Cheonghyang’ grape were 20 °Bx, pH 3.5 and 0.66%, respectively. Total acidity ranged from 0.91∼1.06% in the middle stage of fermentation and decreased to 0.77∼0.82% when alcoholic fermentation finished. Alcohol content in wines ranged from 12.5% to 12.9% showing no significant difference in yeast strains. Wine fermented with Red Fruit had high volatile acid content (189.0 ㎎/L) whereas wine fermented with Fermivin indicated low volatile acid content (77.7 ㎎/L). Wines made with Montrachet, Fermivin and Aroma White had low brightness (L-value) compared to others. Results from sensory evaluation demonstrated that commercial wine yeasts, Montrachet and Fermivin, can be applied to improve sensory properties of ‘Cheonghyang’ wine such as aroma, acidity and transperency. On the other hand, preferences of wine fermented with EC-1118 strain containing lots of tannins and total polyphenols were significantly reduced.

The effect of repetitive controlled oxidation on the chemical and sensory composition of a fresh and fruity style Sauvignon blanc wine was investigated. Chemical analyses were conducted together with extensive sensory profiling. A decrease in volatile thiols responsible for the fruity nuances and an increase in oxidation-related compounds, such as acetaldehyde, during the course of the oxidation was observed. The wine evolved from a fresh and fruity one to one with slight oxidation and then developed extreme oxidative characteristics. The control samples (no oxygen added) developed a "cooked" character that could indicate the formation of "reductive" compounds in these wines. Conversely, the wines that received a single dose of oxygen did not develop this flavor and were perceived to be fresher and fruitier than the control samples. The color of the wine evolved before the disappearance of the pleasant aroma.

In this study, the aromatic profiles of Cabernet Sauvignon wine and the diversity of non-Saccharomyces yeast in industrial-scale spontaneous fermentation (SF) and inoculated fermentation (IF) were investigated. The wine obtained from SF had distinct aromatic profiles compared with IF wine. SF wine was characterized by a higher amount of medium-chain fatty acids, esters, terpenes (trans-rose oxide) and C13-norisoprenoids (β-damascenone), whereas IF wine featured more aldehydes and higher alcohols. Five non-Saccharomyces yeast species, including Hanseniaspora uvarum, Candida stella, Pichia fermentans, Issatchenkia orientalis and Metschnikowia pulcherrima, were isolated from SF, and their enological traits were examined in mixed fermentation with Saccharomyces cerevisiae, respectively. The mixed culture of P. fermentans and C. stella with S. cerevisiae could generate higher levels of esters, fatty acids and norisoprenoids compared to the monoculture of S. cerevisiae, and a co-culture of M. pulcherrima, I. orientalis and H. uvarum could accumulate higher amounts of higher alcohols. Our results suggested that non-Saccharomyces yeast strains greatly contributed to the fruity aroma quality of SF wine, and the mixed culture of Saccharomyces yeasts with non-Saccharomyces yeasts such as P. fermentans, C. stella or M. pulcherrima is a valuable tool to modulate the volatile profiles and improve the aromatic complexity of wine.

The aim of this work was to enhance—by yeast activity—the quality of red wine produced from black grapes of the Calabrian Gaglioppo variety, used as a model for grapes with reduced synthesis of anthocyanins. Six selected strains of Saccharomyces cerevisiae were used to control winemaking trials. Among the wines, there are significant differences, due to the wine starter used. The following technological parameters were significantly different from strain to strain: total acidity, alcoholic degree, tartaric, malic, lactic, and acetic acid, and free and total SO2; moreover, the following phenolic parameters were significantly different from strain to strain: A420, A520, A620, colour intensity, colour hue, Folin–Ciocalteu index, percentage of DPPH inactivation, total anthocyanins, total polyphenols (A280), total tannins, delphinidin-3-glucoside, cyanidin-3-glucoside, petunidin-3-glucoside, peonidin-3-glucoside, and malvidin-3-glucoside. From a sensory standpoint, significant differences were observed among wine samples during a short bottle aging. Data validate the main role that wine yeast selection plays in enhancing the quality of red wine from low pigmented grape.

The aim of this study to evaluate the effects of sulphur dioxide (SO2) on strawberry wine fermentation and on the quality of the final wine product. Major aroma compounds, reducing sugars, ethanol, titratable acid and microflora were analyzed during the fermentation of strawberry wine supplemented with 0–100 mg/L SO2. As the amount of added SO2 increased, the consumption of reducing sugars and soluble solids and ethanol production decreased during early fermentation, but increased during late fermentation. During the fermentation process, the concentrations of 2-phenethanol, isobutanol and isopentanol significantly increased and those of n-propanol, isoamyl acetate and ethyl lactate decreased with increasing amount of added SO2. The production of n-butanol, ethyl acetate and ethyl butyrate was slightly dependent on the amount of added SO2. Yeast cells were the dominant microbe in the fermenting strawberry pulp, and indigenous bacteria and fungi populations decreased rapidly or disappeared because of their sensitivity to SO2. It was concluded that 60–80 mg/L SO2 should be added during strawberry wine fermentations to improve wine quality. Copyright © 2016 The Institute of Brewing & Distilling

Background and Aims Commercial enzyme preparations used in winemaking are mixtures of several enzymatic activities, such as pectinases, cellulases and hemicellulases. The aim of this work was to evaluate the side activities of commercial enzyme preparations and their collateral effects on white wine. Methods and Results The β-glucosidase, cinnamoyl esterase and protease activities of 15 enzyme preparations currently available in the market were screened. Must was treated with the enzyme preparations, and the collateral effects on white wine were evaluated. The application of cinnamoyl esterase-rich preparations induced an increase in hydroxycinnamic acids and 4-vinylguaiacol in the wine that reached a final concentration about twice that of the no enzyme control. Cinnamoyl esterase activity, above 50 U/g or mL of preparation on chlorogenic acid, leads to the risk of an increase of the volatile phenols during fermentation. Enzyme addition to the must influenced the aromatic composition of wine in terms of alcohol, volatile acids and esters. Enzyme treatment led to a decrease in protein concentration and a reduction of haze but was ineffective in resolving protein instability. Conclusions Enzyme preparations formulated for aroma release are more prone to induce collateral effects during winemaking. Significance of the Study Our study clearly highlights that enzyme treatment of must may significantly affect the volatile composition of wine. This result can assist the choice of the most suitable enzyme treatment to improve wine composition.

Nowadays supplementing red wines with commercial inactive dry yeasts is a widespread practice in winemaking because it leads to better balanced wines through increased mouthfeel and smooth astringency. The aim of this article is to study, in a red wine and in a model wine solution, how supplementation with three commercial inactive dry yeasts affects chemical composition and astringency. This will give us a better understanding of the action mechanism involved. RESULTS The results suggest that this action mechanism is related to two different phenomena. The first is that inactive yeasts release polysaccharides and oligosaccharides which can increase mouthfeel and inhibit interactions between salivary protein and tannins. The second is that they have a direct effect on the precipitation or absorption of proanthocyanidins, especially the larger polymers, which have been described as the most astringent. CONCLUSION It can be concluded that supplementation with inactive yeasts is indeed a useful tool for smoothing the astringency of red wines. ? 2016 Society of Chemical Industry

The production of sparkling wines is the result of two consecutive alcoholic fermentations. The first is the fermentation of the grape juice, through which the base wine is obtained, which is fermented again by yeast to enable the effervescence process in bottles. As the use of active dry yeast after rehydration is usually direct and simple, the inoculation of base wine by yeast requires certain preparations to ensure good yeast growth under these conditions: 10% (v/v) of ethanol, low pH, low temperature, etc. Although there are industrial protocols that are widely used to adapt wine yeast to these conditions, information is scarce with respect to the physiological state of strains during the acclimation process. In this study, a commercial wine yeast was acclimated according to different conditions in terms of aeration and sugar content, and used to inoculate a defined base wine to ferment at 25 °C in the bottle. The results showed that some physiological parameters played a decisive role with respect to reaching the maximum pressure of 6 bars in bottles. These parameters were higher glycogen and trehalose contents, lower ROS accumulation, better vacuolar activity and lower ratios of ergosterol/squalene and oleic acid/stearic acid.

Considering the carcinogenic risk to human health, it is necessary to carry out research into arsenic (As) content in agro-food products and the impact of food processing on the final content. Yeast fermentation may represent a strategy for detoxifying some widespread beverages such as wine, beer and rice wine. A preliminary study of some commercial yeast species showed different viability responses to the presence of As. Yeasts had a noteworthy detoxification capability during fermentation, reducing the initial As content by about 75 % on average (minimum–maximum: 45–92 %), making it possible to produce wines with a considerably reduced content as compared to the corresponding grape juices from naturally As-rich soils. Nevertheless, significant differences between strains were observed in relation to resistance to arsenic toxicity and As removal capability. The choice of yeast strain can determine a difference of 40 % on the As content remaining in the wine after fermentation. Arsenic content of up to 1000 µg/L did not significantly worsen the fermentation of some wine yeasts, suggesting that the use of specific yeasts may represent an effective tool for reducing As in fermented beverages.

The aim of this study has been to investigate if wine matrix composition might influence the interaction between odorants and oral mucosa in the oral cavity during a “wine intake-like” situation. Aroma released after exposing the oral cavity of three individuals to different wines (n = 12) previously spiked with six target aromas was followed by an -in vivo intra-oral SPME approach. Results showed a significant effect of wine matrix composition on the intra-oral aroma release of certain odorants. Among the wine matrix parameters, phenolic compounds showed the largest impact. This effect was dependent on their chemical structure. Some phenolic acids (e.g. hippuric, caffeic) were associated to an increase in the intra-oral release of certain odorants (e.g. linalool, β-ionone), while flavonoids showed the opposite effect, decreasing the intra-oral release of aliphatic esters (ethyl hexanoate). This work shows for the first time, the impact of wine composition on oral-mucosa interactions under physiological conditions., A.E-F thanks MINECO for her PhD research FPI contract. C.M-G thanks the funding received from the EU’s Seventh Framework Programme under grant agreement N° FP7-609398 (AgreenSkills+ contract).

The yeast (Saccharomyces cerevisiae) strain 2137 involved in lychee wine production was used to investigate acetate metabolism at different temperatures during lychee wine fermentation. Fermentation tests were conducted using lychee juice supplemented with acetic acid. The ability of yeast cells to metabolize acetic acid was stronger at 20 °C than at 25 °C or 30 °C. The addition of acetic acid suppressed the yeast cell growth at the tested temperatures. The viability was higher and the reactive oxygen species concentration was lower at 20 °C than at 30 °C; this result indicated that acid stress adaptation protects S. cerevisiae from acetic-acid-mediated programmed cell death. The acetic acid enhanced the thermal death of yeast at high temperatures. The fermentation temperature modified the metabolism of the yeasts and the activity of related enzymes during deacidification, because less acetaldehyde, less glycerol, more ethanol, more succinic acid and more malic acid were produced, with higher level of acetyl–CoA synthetase and isocitrate lyase activity, at 20 °C.

Background and Aims Wine aroma is influenced by complex interactions between various wine constituents. This study investigated the sensory interactive effects of Sauvignon Blanc impact compounds, 3-mercaptohexan-1-ol and 3-isobutyl-2-methoxypyrazine, with acetaldehyde that typically forms during the oxidation of wine. Methods and Results Spiked model wines were subjected to sensory descriptive analysis using a trained sensory panel. The concentration of each compound varied from below aroma threshold values to high values as reported for wine. Depending on the concentration, acetaldehyde enhanced fruity attributes at a lower concentration, whereas suppression occurred at a higher concentration. Acetaldehyde effectively suppressed the green pepper aroma attribute at certain concentration values, whereas 3-mercaptohexan-1-ol suppressed oxidised green apple associated with acetaldehyde. Changes in attributes used for aroma description also occurred because of change in concentration. Conclusions Complex sensory interactions may occur between Sauvignon Blanc impact compounds and one of the main oxidation-derived compounds, acetaldehyde. Acetaldehyde can enhance or suppress pleasant fruity characters depending on the concentration. Significance of the Study This study showed the potential positive effect of acetaldehyde on white wine aroma when present at a low concentration. Formation of this compound during winemaking and ageing should, however, be controlled because of negative sensory interactions occurring at a higher concentration. This study may also contribute to the sensory characterisation of Sauvignon Blanc wine undergoing oxidation.

The present study shows the effect of different types of mold, especially microorganisms isolated from the corks, on Tokaj white wines. The transformation in wine chemical composition induced by contamination with molds such as Penicillium chrysogenum, Penicillium expansum and Phanerochaete spp. was different in each type of mold. Molds can contaminate wine either by transferring from grapes contaminated or by non-hygienic conditions during wine technology. As a result of contamination, molds modify wine chemical composition in terms of total and volatile acidity, residual sugars, alcohol volume, total solids and ash.

Fermentation temperature strongly affects yeast metabolism during apple wine making and thus aromatic and quality profiles. In this study, the temperature effect during apple wine making on both the key aroma compounds and sensory properties of apple wine were investigated. The concentration of nine key aroma compounds (ethyl acetate, isobutyl acetate, isopentylacetate, ethyl caprylate, ethyl 4-hydroxybutanoate, isobutylalcohol, isopentylalcohol, 3-methylthio-1-propanol, and benzeneethanol) in apple wine significantly increased with the increase of fermentation temperature from 17 to 20 °C, and then eight out of the nine key aroma compounds with an exception of ethyl 4-hydroxybutanoate, decreased when the temperature goes up 20 to 26 °C. Sensory analysis showed that the apple wine fermented at 20 °C had the highest acceptance for consumers. Fermentation at the temperature of 20 °C was therefore considered to be the most suitable condition using the selected yeast strain (Saccharomyces cerevisiae AP05) for apple wine making. Changes in the fermentation temperature can considerably affect the production of key aroma compounds and sensory profiles of apple wine. These results could help apple wine producers make better quality production for consumers at the optimal fermentation temperature.

Background and Aims Oxygen (O2) plays a fundamental role in the establishment of wine style and aroma. The effect of O2 treatment during fermentation on the formation of volatile sulfur compounds (VSCs) and the subsequent impact on the sensory profile of wine was investigated. Traditional VSC remediation strategies were also evaluated. Methods and Results Shiraz wines were treated with O2 at several levels during fermentation by sparging rotary fermenters with three types of gas mixtures (40% O2, 21% O2 and N2). The controls were not sparged with any gas and were subsequently subjected to three remedial treatments (aerative racking, early- and late-Cu2+ addition). Wines were analysed for VSCs, fermentation products, concentration of residual metals, as well as their sensory profile. Non-oxygenated ferments and wines contained a higher concentration of VSCs and a lower concentration of fermentation products and differences in the concentration of metals. Volatile sulfur compounds responsive to O2 treatment were identified and a relationship between O2 dose and concentration on VSC formation was demonstrated. The ‘early-Cu2+ addition’ remediation strategy proved the most effective in reducing the impact of ‘reductive’ aromas in non-oxygenated wines. Conclusions The risk of producing a wine with high VSC concentration that negatively impacts wine aroma as well as with a low concentration of fermentation products associated with positive red fruit aromas was decreased by treating wines with O2 during fermentation. Significance of the Study This work specifically examines important aspects of O2 treatment during fermentation in relation to ‘reductive’ aroma characters and the overall impact on the wine's sensory attributes.

In this study, the physicochemical properties, antioxidant capacities, and volatile flavor compounds of oriental melon wine prepared by freeze concentration after heat treatment (HA), ascorbic acid treatment (AAT), and heat and ascorbic acid treatment (HAAT) were investigated. During fermentation period, the melon wine by HAAT showed greater reduction of soluble solids and reducing sugar contents compared to other treatments. In addition, the melon wine treated with HAAT also showed a higher L value and lower browning index compared to other treatments. After aging, free sugar including fructose, and organic acids including citric acid, succinic acid, and malic acid were detected in all samples. For antioxidant activities and contents, HAAT treated wine showed greater antioxidant activities and total phenolic contents than those of others. In GC/MS analysis, a total of 33 volatile flavor compounds were identified. In the principal component analysis of volatile flavor compounds, principal components 1 and 2 repre- sented 88.15% of the whole date distribution and showed opposite tendencies. Taken together, HAAT enhanced the antioxidant activities and sensory properties of oriental melon wine. Moreover, freeze concentration gave the different volatile flavor characteristics in oriental melon wine.

Volatile sulfur compounds (VSCs) play a significant role in the aroma of foods and beverages. With very low sensory thresholds and strong unpleasant aromas, most VSCs are considered to have a negative impact on wine quality. In this study, headspace solid phase microextraction coupled with gas chromatography-mass spectrometry (HS-SPME/GC-MS) was used to analyze the time course of the biosynthesis of 12 VSCs formed during wine fermentation. Two different strains of Saccharomyces cerevisiae, the laboratory strain BY4743 and a commercial strain, F15, were assessed using two media: synthetic grape media and Sauvignon Blanc juice. Seven VSCs were detected above background, with three rising above their sensory thresholds. The data revealed remarkable differences in the timing and evolution of production during fermentation, with a transient spike in methanethiol production early during anaerobic growth. Heavier VSCs such as benzothiazole and S-ethyl thioacetate were produced at a steady rate throughout grape juice fermentation, whereas others, such as diethyl sulfide, appear toward the very end of the winemaking process. The results also demonstrate significant differences between yeast strains and fermentation media.

Although phenolics are recognized to be related with health benefits by limiting lipid oxidation, in wine, they are the primary substrates for oxidation resulting in the quinone by-products with the participation of transition metal ions. Nevertheless, high quality Port wines require a period of aging in either bottle or barrels. During this time, a modification of sensory properties of wines such as the decrease of astringency or the stabilization of color is recognized to phenolic compounds, mainly attributed to anthocyanins and derived pigments. The present work aims to illustrate the oxidation of red Port wine based on its phenolic composition by the effect of both thermal and oxygen exposures. A kinetic approach toanthocyanins degradation was also achieved. For this purpose a forced red Port wine aging protocol was performed at four different storage temperatures, respectively, 20, 30, 35 and 40 degrees C, and two adjusted oxygen saturation levels, no oxygen addition (treatment I), and oxygen addition (treatment II). Three hydroxycinnamic esters, three hydroxycinnamic acids, three hydroxybenzoic acids, two flavan-3-ols, and six anthocyanins were quantitated weekly during 63 days, along with oxygen consumption. The most relevant phenolic oxidation markers were anthocyanins and catechin-type flavonoids, which had the highest decreases during the thermal and oxidative red Port wine process. Both temperature and oxygen treatments affected the rate of phenolic degradation. In addition, temperature seems to influence mostly the phenolics kinetic degradation.

Organic acids of wine, in addition to ethanol, have been identified as stimulants of gastric acid secretion. This study characterized the influence of other wine compounds, particularly phenolic compounds, on proton secretion. Forty wine parameters were determined in four red wines and six white wines, including the contents of organic acids and phenolic compounds. The secretory activity of the wines was determined in a gastric cell culture model (HGT-1 cells) by means of a pH-sensitive fluorescent dye. Red wines stimulated proton secretion more than white wines. Lactic acid and the phenolic compounds syringic acid, catechin, and procyanidin B2 stimulated proton secretion and correlated with the pro-secretory effect of the wines. Addition of the phenolic compounds to the least active white wine sample enhanced its proton secretory effect by 65 ± 21% (p < 0.05). These results indicate that not only malic and lactic acid but also bitter and astringent tasting phenolic compounds in wine contribute to its stimulatory effect on gastric acid secretion.

Summary This study investigated the impact of single branched-chain amino acid addition (L-valine, L-leucine, L-isoleucine) on nonvolatile and volatile constituents in lychee wine fermented with Saccharomyces cerevisiae MERIT.ferm. The individual addition of branched-chain amino acids decreased the consumption of proline with significantly different rates. The lychee wine with added L-leucine and L-isoleucine had higher odour activity values (OAVs) of isoamyl alcohol, active amyl alcohol and isoamyl acetate. The lychee wine with added L-valine had higher OAVs of isobutyric acid and isobutyl alcohol (5.55 and 2.98, respectively), which were lower in the wine with added L-leucine (2.91 and 1.02, respectively) or L-isoleucine (3.43 and 1.73, respectively) relative to the control wine (4.18 and 1.77, respectively), suggesting interactive effects among the amino acids. These findings demonstrated that lychee wine aroma can potentially be manipulated via the addition of selected branched-chain amino acids.

We investigate black raspberry (Rubus occidentalis) wine made using traditional yeast (Saccharomyces cerevisiae A8, B6, GBY2, GBY3) and S. cerevisiae Fermivin (FM), which is widely used in wine manufacturing, and analyze the biogenic amine content and the volatile flavor compounds. Black raspberries were separately inoculated with yeast up to 1×10 9 CFU/kg, followed by incubation at 25°C for 7 days. FM produced the highest alcohol content, however the final fermentation characteristics of the wine made using four different yeasts were similar. S. cerevisiae A8 had a large biogenic amine (BA) content, specifically tryptamine, thus we excluded this yeast from fermentation. S. cerevisiae GBY3 was selected for black raspberry wine fermentation as a result of sensory evaluation. The volatile flavor compounds of two wines (S. cerevisiae GBY3 and FM) were analyzed by gas chromatography and mass spectrometry. 37 compounds in the samples were separated, and several ester compounds were identified in greater amounts in the wine made with S. cerevisiae GBY3 than in the wine made with FM. A greater amount of the major compound, ethyl benzoate, giving the sweet and fruity flavor, was identified in wine made with S. cerevisiae GBY3 than in the wine made with FM. In conclusion, S. cerevisiae GBY3 was confirmed to produce no major BAs and a better flavored wine. These results give new leads in the production of high quality wine.Key words: black raspberry, traditional yeast, wine, biogenic amine, flavor compound

The objective of this study was to improve the quality of black raspberry wine added with wild grape, based on selection of yeast strains and fermentation conditions. The Y1 yeast(Lalvin 71B) indicated significantly higher lactic acid, ester, fusel oil content after fermented mashing than other samples tested and had an effect on the reduction of acidity and enhanced aroma of black raspberry wine. In addition, the high fermentation temperature(25℃) using Y1 yeast showed much higher tendency to retain components of aroma (ethyl acetate, higher alcohols) and the highest overall preference including sensory evaluation than that of low fermentation temperture(15℃). Thus, the fermentation using Y1 yeast at 25℃ can be applied to positively improve the taste and flavor of production of black raspberry wine added wild grape.

Proanthocyanidins (PAs) derived from the grape skin, as well as from grape seeds, grape stems, are an important group of polyphenols in wine. The aim of this study was to understand the effect of PAs (0.1, 1.0 g/L) on growth and alcoholic fermentation of 2 strains of Saccharomyces cerevisiae (commercial strain FREDDO and newly selected strain BH8) during copper-stress fermentation, using a simple model fermentation system. Our results showed that both PAs and Cu(2+) could pose significant inhibition effects on the growth of yeast cells, CO2 release, sugar consumption, and ethanol production during the initial phase of the fermentation. Compared to PAs, Cu(2+) performed more obvious inhibition on the yeast growth and fermentation. However, adding 1.0 g/L PAs increased in the vitality and metabolism activity of yeast cells at the mid-exponential phase of fermentation in the mediums with no copper and 0.1 mM Cu(2+) added, shortened the period of wine fermentation, and decreased the copper residues. It indicated that PAs could improve the ability of wine yeast to resist detrimental effects under copper-stress fermentation condition, maintaining cells metabolic activity, and fermentation could be controlled by manipulating PAs supplementation.

Bottled white wine may be exposed to UV-visible light for considerable periods of time before it is consumed. Light exposure may induce an off-flavor known as "sunlight" flavor, bleach the color of the wine, and/or increase browning and deplete sulfur dioxide. The changes that occur in bottled white wine exposed to light depend on the wine composition, the irradiation conditions, and the light exposure time. The light-induced changes in the aroma, volatile composition, color, and concentrations of oxygen and sulfur dioxide in bottled white wine are reviewed. In addition, the photochemical reactions thought to have a role in these changes are described. These include the riboflavin-sensitized oxidation of methionine, resulting in the formation of methanethiol and dimethyl disulfide, and the photodegradation of iron(III) tartrate, which gives rise to glyoxylic acid, an aldehyde known to react with flavan-3-ols to form yellow xanthylium cation pigments.