Impact of phenylalanine on Hanseniaspora vineae aroma metabolism during wine fermentation.

Hanseniaspora vineae exhibits extraordinary positive oenological characteristics contributing to the aroma and texture of wines, especially by its ability to produce great concentrations of benzenoid and phenylpropanoid compounds compared with conventional Saccharomyces yeasts. Consequently, in practice, sequential inoculation of H. vineae and Saccharomyces cerevisiae allows to improve the aromatic quality of wines. In this work, we evaluated the impact on wine aroma produced by increasing the concentration of phenylalanine, the main amino acid precursor of phenylpropanoids and benzenoids. Fermentations were carried out using a Chardonnay grape juice containing 150 mg N/L yeast assimilable nitrogen. Fermentations were performed adding 60 mg/L of phenylalanine without any supplementary addition to the juice. Musts were inoculated sequentially using three different H. vineae strains isolated from Uruguayan vineyards and, after 96 h, S. cerevisiae was inoculated to complete the process. At the end of the fermentation, wine aromas were analysed by both gas chromatography-mass spectrometry and sensory evaluation through a panel of experts. Aromas derived from aromatic amino acids were differentially produced depending on the treatments. Sensory analysis revealed more floral character and greater aromatic complexity when compared with control fermentations without phenylalanine added. Moreover, fermentations performed in synthetic must with pure H. vineae revealed that even tyrosine can be used in absence of phenylalanine, and phenylalanine is not used by this yeast for the synthesis of tyrosine derivatives.

Tannat grape pomace as an ingredient for potential functional biscuits: bioactive compound identification, in vitro bioactivity, food safety, and sensory evaluation.

Grape pomace, the main by-product of wine process, shows high potential for the development of functional foods, being a natural source of bioactive compounds and dietary fiber. Thus, the present study proposes the development of five potential functional biscuits. The five formulations were achieved by varying the Tannat grape pomace powder (TGP, 10-20% w/w total wet dough) and sweetener sucralose (2-4% w/w total wet dough) content through a factorial design with central points. TGP microbiological and pesticides analysis were performed as a food safety requirement. Identification of bioactive compounds by HPLC-DAD-MS, in vitro bioactivity (total phenol content, antioxidant by ABTS and ORAC-FL, antidiabetic and antiobesity by inhibition of α-glucosidase and pancreatic lipase, respectively) and sensory properties of the biscuits were evaluated. TGP microbiological and pesticides showed values within food safety criteria. Sensory profiles of TGP biscuits were obtained, showing biscuits with 20% TGP good sensory quality (7.3, scale 1-9) in a cluster of 37 out of 101 consumers. TGP addition in biscuits had a significant (p < 0.05) effect on total phenolic content (0.893-1.858 mg GAE/g biscuit) and bioactive properties when compared to controls: 11.467-50.491 and 4.342-50.912 µmol TE/g biscuit for ABTS and ORAC-FL, respectively; inhibition of α-glucosidase and pancreatic lipase, IC50 35.572-64.268 and 7.197-47.135 mg/mL, respectively. HPLC-DAD-MS results showed all the identified phenolic compounds in 20/4% biscuit (TGP/sucralose%) were degraded during baking. Malvidin-3-O-(6'-p-coumaroyl) glucoside, (+)-catechin, malvidin-3-O-glucoside, and (-)-epicatechin were the main phenolic compounds (in descendent order of content) found. The bioactive properties could be attributed to the remaining phenolic compounds in the biscuits. In conclusion, TGP biscuits seemed to be a promising functional food with potential for ameliorating oxidative stress, glucose and fatty acids levels with good sensory quality.

Antioxidant Capacity and NF-kB-Mediated Anti-Inflammatory Activity of Six Red Uruguayan Grape Pomaces.

Grape pomaces have a wide and diverse antioxidant phenolics composition. Six Uruguayan red grape pomaces were evaluated in their phenolics composition, antioxidant capacity, and anti-inflammatory properties. Not only radical scavenging methods as DPPH· and ABTS·+ were employed but also ORAC and FRAP analyses were applied to assess the antioxidant potency of the extracts. The antioxidant reactivity of all extracts against hydroxyl radicals was assessed with ESR. The phenol profile of the most bioactive extract was analyzed by HPLC-MS, and a set of 57 structures were determined. To investigate the potential anti-inflammatory activity of the extracts, Nuclear Factor kappa-B (NF-κB) modulation was evaluated in the human colon cancer reporter cell line (HT-29-NF-κB-hrGFP). Our results suggest that Tannat grapes pomaces have higher phenolic content and antioxidant capacity compared to Cabernet Franc. These extracts inhibited TNF-alpha mediated NF-κB activation and IL-8 production when added to reporter cells. A molecular docking study was carried out to rationalize the experimental results allowing us to propose the proactive interaction between the NF-κB, the grape extracts phenols, and their putative anti-inflammatory bioactivity. The present findings show that red grape pomace constitutes a sustainable source of phenolic compounds, which may be valuable for pharmaceutical, cosmetic, and food industry applications.

Commercial craft beers produced in Uruguay: Volatile profile and physicochemical composition.

Even beer being the most consumed alcoholic beverage around the world, there is not enough information generated for craft beers produced in Latin America, for either volatile profiles or physicochemical studies. In this work, the chemical and volatile components of ten commercial Blond Ale and nine Indian Pale Ale (IPA) beers from the Uruguayan market were studied using GC-MS. Principal component analysis applied to the data allowed differentiation among the two groups of samples while the volatile compounds and physicochemical parameters responsible for these differences were identified. The physicochemical properties revealed a great diversity between all beer samples even within the same beer style. The main significant differences were obtained for alcohol, polyphenols, bitterness, colour, and pH. Most Blond Ale beer samples were differentiated from IPA ones by raw fermentation aroma compounds such as 1-pentanol, 1-hexanol, hexanoic and isobutyric acids, 4-vinyl guaiacol, and 5,5-dimethyl-2(5H)-furanone. This is the first work that contributes to the knowledge of Uruguayan craft beers. The study also showed the ability of most of the Uruguayan microbreweries to brew Blond Ale and IPA craft beer styles that meet international standards for physicochemical quality.

Biology and physiology of Hanseniaspora vineae: metabolic diversity and increase flavour complexity for food fermentation.

Apiculate yeasts belonging to the genus Hanseniaspora are predominant on grapes and other fruits. While some species, such as Hanseniaspora uvarum, are well known for their abundant presence in fruits, they are generally characterized by their detrimental effect on fermentation quality because the excessive production of acetic acid. However, the species Hanseniaspora vineae is adapted to fermentation and currently is considered as an enhancer of positive flavour and sensory complexity in foods. Since 2002, we have been isolating strains from this species and conducting winemaking processes with them. In parallel, we also characterized this species from genes to metabolites. In 2013, we sequenced the genomes of two H. vineae strains, being these the first apiculate yeast genomes determined. In the last 10 years, it has become possible to understand its biology, discovering very peculiar features compared to the conventional Saccharomyces yeasts, such as a natural and unique G2 cell cycle arrest or the elucidation of the mandelate pathway for benzenoids synthesis. All these characteristics contribute to phenotypes with proved interest from the biotechnological point of view for winemaking and the production of other foods.

Fecal descriptor in honey: indole from a floral source as an explanation.

BACKGROUND: Animal odor, is one of the most common aroma defects described in the honey odor aroma wheel. It comprises two secondary descriptors: 'fecal' and 'cowshed'. However, the compounds responsible for these honey defects have not been fully identified. In this context, the aim of this work was to identify the compounds responsible for the aromatic defect 'fecal' in Uruguayan honeys by means of gas chromatography coupled to olfactometry (GC-O). RESULTS: Samples of honey described by beekeepers as having fecal aroma were analyzed by GC-O and gas chromatography coupled to mass spectrometry (GC-MS). Through GC-O, it was possible to establish the region of the chromatogram corresponding to the fecal descriptor, while the GC-MS analysis allowed to identify indole as the compound responsible for the fecal descriptor. The content of indole in the analyzed samples ranged between 132 and 414 µg kg-1 . The melissopalynological analysis indicated the presence of Scutia buxifolia ('quebracho' or 'coronilla') pollen in all samples studied. The volatile profile of Scutia buxifolia flowers was evaluated during the full day, enabling the identification of indole as one of its components. The detection threshold value for indole in honey was experimentally determined as 64 µg kg-1 of honey, a value lower than the concentration found in the evaluated samples. CONCLUSION: Results from the study allowed the identification of indole as the compound responsible for the 'fecal' aroma defect in Scutia buxifolia honeys. © 2022 Society of Chemical Industry.

Application of near-infrared spectroscopy/artificial neural network to quantify glycosylated norisoprenoids in Tannat grapes.

Grape variety, vinification, and ageing are factors conditioning the aroma of a wine, with volatile secondary metabolites responsible for the so-called grape varietal character. Particularly, grape glycosylated norisoprenoids are mostly responsible for the sensory profile of Tannat wines, making relevant the use of fast instrumental tools to evaluate their concentration, allow classifying grapes and defining the optimum maturity for harvest. NIR spectroscopy is a fast, non-destructive technique, which requires minimal sample preparation. However, its quantitative applications need chemometric models for interpretation. In this work, a NIR-ANN calibration was developed to quantify norisoprenoids in Vitis vinifera cv. Tannat grapes during maturation and harvesting. Glycosidated norisoprenoids were determined by GC-MS. The ANN adjustments showed better performance than linear models such as PLS, while the best calibration was obtained by homogenising grape samples when comparing to grape juice; making possible to fit a model with an error of 146 µg/kg.

Simultaneous identification to monitor consortia strain dynamics of four biofuel yeast species during fermentation.

Mixed strain dynamics are still not well or easily monitored although recently molecular identification methods have improved our knowledge. This study used a chromogenic differential plating medium that allows the discrimination of four of the main selected biofuel strains that are currently under development for ethanol production from cellulosic hydrolysates. Complete fermentation of hexoses and xylose was obtained with a yeast consortium composed of Spathaspora passalidarum, Scheffersomyces stipitis, Candida akabanensis and Saccharomyces cerevisiae. The results showed that C.akabanensis excessively dominated consortium balance. Reducing its inoculum from 33 to 4.8% improved population strain balance and fermentation efficiency. Comparison of the consortia with single strain fermentations showed that it optimize sugar consumption and ethanol yields. This simple and cheap method also has advantages compared with molecular methods, as the yeast strains do not need to be genetically marked and identified cell proportions are probably active in the fermentation system as compared to DNA determination methods.

Genetic and transcriptomic evidences suggest ARO10 genes are involved in benzenoid biosynthesis by yeast.

Benzenoids are compounds associated with floral and fruity flavours in flowers, fruits and leaves and present a role in hormonal signalling in plants. These molecules are produced by the phenyl ammonia lyase pathway. However, some yeasts can also synthesize them from aromatic amino acids using an alternative pathway that remains unknown. Hanseniaspora vineae can produce benzenoids at levels up to two orders of magnitude higher than Saccharomyces species, so it is a model microorganism for studying benzenoid biosynthesis pathways in yeast. According to their genomes, several enzymes have been proposed to be involved in a mandelate pathway similar to that described for some prokaryotic cells. Among them, the ARO10 gene product could present benzoylformate decarboxylase activity. This enzyme catalyses the decarboxylation of benzoylformate into benzaldehyde at the end of the mandelate pathway in benzyl alcohol formation. Two homologous genes of ARO10 were found in the two sequenced H. vineae strains. In this study, nine other H. vineae strains were analysed to detect the presence and per cent homology of ARO10 sequences by PCR using specific primers designed for this species. Also, the copy number of the genes was estimated by quantitative PCR. To verify the relation of ARO10 with the production of benzyl alcohol during fermentation, a deletion mutant in the ARO10 gene of Saccharomyces cerevisiae was used. The two HvARO10 paralogues were analysed and compared with other α-ketoacid decarboxylases at the sequence and structural level.

The Mandelate Pathway, an Alternative to the Phenylalanine Ammonia Lyase Pathway for the Synthesis of Benzenoids in Ascomycete Yeasts.

Benzenoid-derived metabolites act as precursors for a wide variety of products involved in essential metabolic roles in eukaryotic cells. They are synthesized in plants and some fungi through the phenylalanine ammonia lyase (PAL) and tyrosine ammonia lyase (TAL) pathways. Ascomycete yeasts and animals both lack the capacity for PAL/TAL pathways, and metabolic reactions leading to benzenoid synthesis in these organisms have remained incompletely known for decades. Here, we show genomic, transcriptomic, and metabolomic evidence that yeasts use a mandelate pathway to synthesize benzenoids, with some similarities to pathways used by bacteria. We conducted feeding experiments using a synthetic fermentation medium that contained either 13C-phenylalanine or 13C-tyrosine, and, using methylbenzoylphosphonate (MBP) to inhibit benzoylformate decarboxylase, we were able to accumulate intracellular intermediates in the yeast Hanseniaspora vineae To further confirm this pathway, we tested in separate fermentation experiments three mutants with deletions in the key genes putatively proposed to form benzenoids (Saccharomyces cerevisiaearo10Δ, dld1Δ, and dld2Δ strains). Our results elucidate the mechanism of benzenoid synthesis in yeast through phenylpyruvate linked with the mandelate pathway to produce benzyl alcohol and 4-hydroxybenzaldehyde from the aromatic amino acids phenylalanine and tyrosine, as well as sugars. These results provide an explanation for the origin of the benzoquinone ring, 4-hydroxybenzoate, and suggest that Aro10p has benzoylformate and 4-hydroxybenzoylformate decarboxylase functions in yeast.IMPORTANCE We present here evidence of the existence of the mandelate pathway in yeast for the synthesis of benzenoids. The link between phenylpyruvate- and 4-hydroxyphenlypyruvate-derived compounds with the corresponding synthesis of benzaldehydes through benzoylformate decarboxylation is demonstrated. Hanseniaspora vineae was used in these studies because of its capacity to produce benzenoid derivatives at a level 2 orders of magnitude higher than that produced by Saccharomyces Contrary to what was hypothesized, neither ß-oxidation derivatives nor 4-coumaric acid is an intermediate in the synthesis of yeast benzenoids. Our results might offer an answer to the long-standing question of the origin of 4-hydroxybenzoate for the synthesis of Q10 in humans.

Valorisation of Schinus molle fruit as a source of volatile compounds in foods as flavours and fragrances.

Schinus molle L. (Anacardiaceae) is an evergreen tree native to South America and has been introduced into North and South Africa and the Mediterranean region. The mature berries are known as an alternative to pepper by their pungency and collected for essential oil production to substitute black pepper in perfumery. Several investigators have examined the physicochemical properties and chemical composition of the essential oil, but the release of bound volatile compounds in S. molle berries from the corresponding glycosides is presented here for the first time. The carotenoid content of mature berries was also studied over two successive ripening periods. Ten carotenoids were identified by HPLC-MS/MS: lutein, phytoene, ß-cryptoxanthin, phytofluene, ß-carotene, 9-Z-ß-carotene, ß-cryptoxanthin-C12:0, ß-cryptoxanthin-C14:0, ß-cryptoxanthin-C16:0 and lycopene. This research is the first to characterise the carotenoids in molle berries and their degradation products (norisoprenoids) in the "free" and glycosylated volatile fruit fractions. The detection of many of these glycosidically bound volatile compounds in berries should be considered to have a sensory contribution, which might differentiate the volatile profile. In addition, our results could explain, through the flavour complexity found in both the "free" and glycosylated fractions, the reported traditional use of molle berries as a pepper substitute. For comparison purposes, the essential oil from mature berries obtained by hydrodistillation was also studied.

Yeasts for low input winemaking: Microbial terroir and flavor differentiation.

Vitis vinifera flowers and grape fruits are one of the most interesting ecosystem niches for native yeasts development. There are more than a 100 yeast species and millions of strains that participate and contribute to design the microbial terroir. The wine terroir concept is understood when grape and wine micro-regions were delimited by different quality characteristics after humans had been growing vines for more than 10,000 years. Environmental conditions, such as climate, soil composition, water management, winds and air quality, altitude, fauna and flora and microbes, are considered part of the "terroir" and contribute to a unique wine style. If "low input winemaking" strategies are applied, the terroir effect will be expected to be more authentic in terms of quality differentiation. Interestingly, the role of the microbial flora associated with vines was very little study until recently when new genetic technologies for massive species identification were developed. These biotechnologies allowed following their environmental changes and their effect in shaping the microbial profiles of different wine regions. In this chapter we explain the interesting positive effects on flavor diversity and wine quality obtained by using "friendly" native yeasts that allowed the microbial terroir flora to participate and contribute during fermentation.

Genomic and Transcriptomic Basis of Hanseniaspora vineae's Impact on Flavor Diversity and Wine Quality.

Hanseniaspora is the main genus of the apiculate yeast group that represents approximately 70% of the grape-associated microflora. Hanseniaspora vineae is emerging as a promising species for quality wine production compared to other non-Saccharomyces species. Wines produced by H. vineae with Saccharomyces cerevisiae consistently exhibit more intense fruity flavors and complexity than wines produced by S. cerevisiae alone. In this work, genome sequencing, assembling, and phylogenetic analysis of two strains of H. vineae showed that it is a member of the Saccharomyces complex and it diverged before the whole-genome duplication (WGD) event from this clade. Specific flavor gene duplications and absences were identified in the H. vineae genome compared to 14 fully sequenced industrial S. cerevisiae genomes. The increased formation of 2-phenylethyl acetate and phenylpropanoids such as 2-phenylethyl and benzyl alcohols might be explained by gene duplications of H. vineae aromatic amino acid aminotransferases (ARO8 and ARO9) and phenylpyruvate decarboxylases (ARO10). Transcriptome and aroma profiles under fermentation conditions confirmed these genes were highly expressed at the beginning of stationary phase coupled to the production of their related compounds. The extremely high level of acetate esters produced by H. vineae compared to that by S. cerevisiae is consistent with the identification of six novel proteins with alcohol acetyltransferase (AATase) domains. The absence of the branched-chain amino acid transaminases (BAT2) and acyl coenzyme A (acyl-CoA)/ethanol O-acyltransferases (EEB1) genes correlates with H. vineae's reduced production of branched-chain higher alcohols, fatty acids, and ethyl esters, respectively. Our study provides sustenance for understanding and potentially utilizing genes that determine fermentation aromas.IMPORTANCE The huge diversity of non-Saccharomyces yeasts in grapes is dominated by the apiculate genus Hanseniaspora Two native strains of Hanseniaspora vineae applied to winemaking because of their high oenological potential in aroma and fermentation performance were selected to obtain high-quality genomes. Here, we present a phylogenetic analysis and the complete transcriptome and aroma metabolome of H. vineae during three fermentation steps. This species produced significantly richer flavor compound diversity than Saccharomyces, including benzenoids, phenylpropanoids, and acetate-derived compounds. The identification of six proteins, different from S. cerevisiae ATF, with diverse acetyltransferase domains in H. vineae offers a relevant source of native genetic variants for this enzymatic activity. The discovery of benzenoid synthesis capacity in H. vineae provides a new eukaryotic model to dilucidate an alternative pathway to that catalyzed by plants' phenylalanine lyases.

Relationship between astringency and phenolic composition of commercial Uruguayan Tannat wines: Application of boosted regression trees.

Phenolic compounds play a major role in the intensity and characteristics of wine astringency. However, studies involving commercial wine samples are still scarce. The aim of the present work was to study the relationship between astringency and phenolic composition of commercial Uruguayan Tannat wines using boosted regression trees (BRT), a novel predictive method. Forty commercial Tannat wines were evaluated by a trained sensory panel (9 members), who assessed their total astringency intensity using time-intensity (TI) and described their astringency sub-qualities using a check-all-that-apply (CATA) question composed of sixteen terms. The polyphenolic profiles of the wines were determined by HPLC-MS and conventional oenological parameters were also obtained. Fifty BRT models with different partitions of the data in training and test sets were built for astringency maximum intensity (Imax) and for the frequency of use of the 16 astringency sub-qualities considered in the CATA question. As predictor variables, 84 phenolic compounds and oenological parameters were considered for all BRT models. Both strong and weak predictive models were obtained for each response variable. Predictive accuracy was much higher for astringency intensity than for the frequency of mention of astringency sub-qualities. Still, the BRT models allowed to point out to some compositional variables most likely involved in wine astringency perception. Total tannin concentration (chemically determined) was the most relevant explanatory variable for sensory astringency, while flavan-3-ols were the individual phenolic compounds with the highest contribution to astringency, particularly some dimers, trimers and the sum of non-galloylated tetramers. However, the effect of these predictors differed according to the astringency sub-quality considered as response. As expected, non-linear relationships between phenolic compounds and astringency were found. These results contribute to the understanding of the influence of phenolic composition on wine astringency and stress the potential of BRT models for identifying the compounds responsible for this complex sensory characteristic.

Sensory characterization of the astringency of commercial Uruguayan Tannat wines.

Astringency is one of the most important characteristics that define the quality of red wine, and is of particular relevance for Tannat, Uruguayan emblematic red wine variety. Astringency is a time-dependant and complex sensory characteristic, related to several sensations, or sub-qualities, that can be simultaneously perceived. The aim of the present study was to obtain a sensory characterization of the astringency of commercial Uruguayan Tannat wines. Forty samples with different characteristics in terms of vintage, price segment and aging in oak barrels were assessed by a panel of 9 trained assessors. Total astringency intensity was evaluated using time-intensity (TI), while astringency sub-qualities were described using a check-all-that-apply (CATA) question composed of sixteen terms. TI and the CATA question provided different information on the astringency of Tannat wines. Regarding global astringency, samples mainly differed in intensity-related parameters rather than in the development of astringency over time, although the variability was moderate. A wide range of sub-qualities, from silky and velvety to harsh and aggressive were used to describe the astringency of the evaluated wines. Four groups of samples with different astringency characteristics were identified, but this sorting was not related to vintage, price segment or aging in oak barrels. Further research is necessary to better understand how astringency characteristics are influenced by production variables, and to understand their relationship to consumers' and experts' perceived quality of Tannat wines.

Pineapple (Ananas comosus L. Merr.) wine production in Angola: Characterisation of volatile aroma compounds and yeast native flora.

A pineapple vinification process was conducted through inoculated and spontaneous fermentation to develop a process suitable for a quality beverage during two successive vintages in Huambo, Angola. Wines obtained with the conventional Saccharomyces cerevisiae strain, were analysed by gas chromatography, and a total of 61 volatile constituents were detected in the volatile fraction and 18 as glycosidically bound aroma compounds. Concentration levels of carbonyl and sulphur compounds were in agreement with the limited information reported about pineapple fruits of other regions. We report, for the first time in pineapple wines, the presence of significant concentrations of lactones, ketones, terpenes, norisoprenoids and a variety of volatile phenols. Eight native yeast strains were isolated from spontaneous batches. Further single-strain fermentations allowed us to characterise their suitability for commercial fermentation. Three native strains (Hanseniaspora opuntiae, H. uvarum and Meyerozyma guilliermondii) were selected with sensory potential to ferment pineapple fruits with increased flavour diversity. Results obtained here contribute to a better understanding of quality fermentation alternatives of this tropical fruit in subtropical regions.

De Novo Synthesis of Benzenoid Compounds by the Yeast Hanseniaspora vineae Increases the Flavor Diversity of Wines.

Benzyl alcohol and other benzenoid-derived metabolites of particular importance in plants confer floral and fruity flavors to wines. Among the volatile aroma components in Vitis vinifera grape varieties, benzyl alcohol is present in its free and glycosylated forms. These compounds are considered to originate from grapes only and not from fermentative processes. We have found increased levels of benzyl alcohol in red Tannat wine compared to that in grape juice, suggesting de novo formation of this metabolite during vinification. In this work, we show that benzyl alcohol, benzaldehyde, p-hydroxybenzaldehyde, and p-hydroxybenzyl alcohol are synthesized de novo in the absence of grape-derived precursors by Hanseniaspora vineae. Levels of benzyl alcohol produced by 11 different H. vineae strains were 20-200 times higher than those measured in fermentations with Saccharomyces cerevisiae strains. These results show that H. vineae contributes to flavor diversity by increasing grape variety aroma concentration in a chemically defined medium. Feeding experiments with phenylalanine, tryptophan, tyrosine, p-aminobenzoic acid, and ammonium in an artificial medium were tested to evaluate the effect of these compounds either as precursors or as potential pathway regulators for the formation of benzenoid-derived aromas. Genomic analysis shows that the phenylalanine ammonia-lyase (PAL) and tyrosine ammonia lyase (TAL) pathways, used by plants to generate benzyl alcohols from aromatic amino acids, are absent in the H. vineae genome. Consequently, alternative pathways derived from chorismate with mandelate as an intermediate are discussed.

Effect of yeast assimilable nitrogen on the synthesis of phenolic aroma compounds by Hanseniaspora vineae strains.

In several grape varieties, the dominating aryl alkyl alcohols found are the volatile group of phenylpropanoid-related compounds, such as glycosylated benzyl and 2-phenylethyl alcohol, which contribute to wine with floral and fruity aromas after being hydrolysed during fermentation. Saccharomyces cerevisiae is largely recognized as the main agent in grape must fermentation, but yeast strains belonging to other genera, including Hanseniaspora, are known to predominate during the first stages of alcoholic fermentation. Although non-Saccharomyces yeast strains have a well-recognized genetic diversity, understanding of their impact on wine flavour richness is still emerging. In this study, 11 Hansenisapora vineae strains were used to ferment a chemically defined simil-grape fermentation medium, resembling the nutrient composition of grape juice but devoid of grape-derived secondary metabolites. GC-MS analysis was performed to determine volatile compounds in the produced wines. Our results showed that benzyl alcohol, benzyl acetate and 2-phenylethyl acetate are significantly synthesized by H. vineae strains. Levels of these compounds found in fermentations with 11 H. vineae different strains were one or two orders of magnitude higher than those measured in fermentations with a known S. cerevisiae wine strain. The implications for winemaking in response to the negative correlation of benzyl alcohol, benzyl acetate and 2-phenylethyl acetate production with yeast assimilable nitrogen concentrations are discussed. Copyright © 2016 John Wiley & Sons, Ltd.

Non-Saccharomyces and Saccharomyces strains co-fermentation increases acetaldehyde accumulation: effect on anthocyanin-derived pigments in Tannat red wines.

During fermentation, Saccharomyces cerevisiae releases into the medium secondary metabolic products, such as acetaldehyde, able to react with anthocyanins, producing more stable derived pigments. However, very limited reports are found about non-Saccharomyces effects on grape fermentation. In this study, six non-Saccharomyces yeast strains, belonging to the genera Metschnikowia and Hanseniaspora, were screened for their effect on red wine colour and wine-making capacity under pure culture conditions and mixed with Saccharomyces. An artificial red grape must was prepared, containing a phenolic extract of Tannat grapes that allows monitoring changes of key phenol parameters during fermentation, but without skin solids in the medium. When fermented in pure cultures, S. cerevisiae produced higher concentrations of acetaldehyde and vitisin B (acetaldehyde reaction-dependent) compared to M. pulcherrima M00/09G, Hanseniaspora guillermondii T06/09G, H. opuntiae T06/01G, H. vineae T02/05F and H. clermontiae (A10/82Fand C10/54F). However, co-fermentation of H. vineae and H. clermontiae with S. cerevisiae resulted in a significantly higher concentration of acetaldehyde compared with the pure S. cerevisiae control. HPLC-DAD-MS analysis confirmed an increased formation of vitisin B in co-fermentation treatments when compared to pure Saccharomyces fermentation, suggesting the key role of acetaldehyde. Copyright © 2016 John Wiley & Sons, Ltd.

How do consumers describe wine astringency?

Astringency is one of the most important sensory characteristics of red wine. Although a hierarchically structured vocabulary to describe the mouthfeel sensations of red wine has been proposed, research on consumers' astringency vocabulary is lacking. In this context, the aim of this work was to gain an insight on the vocabulary used by wine consumers to describe the astringency of red wine and to evaluate the influence of wine involvement on consumers' vocabulary. One hundred and twenty-five wine consumers completed and on-line survey with five tasks: an open-ended question about the definition of wine astringency, free listing the sensations perceived when drinking an astringent wine, free listing the words they would use to describe the astringency of a red wine, a CATA question with 44 terms used in the literature to describe astringency, and a wine involvement questionnaire. When thinking about wine astringency consumers freely elicited terms included in the Mouth-feel Wheel, such as dryness and harsh. The majority of the specific sub-qualities of the Mouth-feel Wheel were not included in consumer responses. Also, terms not classified as astringency descriptors were elicited (e.g. acid and bitter). Only 17 out of the 31 terms from the Mouth-feel Wheel were used by more than 10% of participants when answering the CATA question. There were no large differences in the responses of consumer segments with different wine involvement. Results from the present work suggest that most of the terms of the Mouth-feel Wheel might not be adequate to communicate the astringency characteristics of red wine to consumers.