Bioprotection Efficiency of Metschnikowia Strains in Synthetic Must: Comparative Study and Metabolomic Investigation of the Mechanisms Involved.

Three Metschnikowia strains marketed as bioprotection yeasts were studied to compare their antimicrobial effect on a mixture of two Hanseniaspora yeast strains in synthetic must at 12 °C, mimicking pre-fermentative maceration by combining different approaches. The growth of the different strains was monitored, their nitrogen and oxygen requirements were characterised, and their metabolomic footprint in single and co-cultures studied. Only the M. fructicola strain and one M. pulcherrima strains colonised the must and induced the rapid decline of Hanseniaspora. The efficiency of these two strains followed different inhibition kinetics. Furthermore, the initial ratio between Metschnikowia and Hanseniaspora was an important factor to ensure optimal bioprotection. Nutrient consumption kinetics showed that apiculate yeasts competed with Metschnikowia strains for nutrient accessibility. However, this competition did not explain the observed bioprotective effect, because of the considerable nitrogen content remaining on the single and co-cultures. The antagonistic effect of Metschnikowia on Hanseniaspora probably implied another form of amensalism. For the first time, metabolomic analyses of the interaction in a bioprotection context were performed after the pre-fermentative maceration step. A specific footprint of the interaction was observed, showing the strong impact of the interaction on the metabolic modulation of the yeasts, especially on the nitrogen and vitamin pathways.

Probiotic Yeasts and How to Find Them-Polish Wines of Spontaneous Fermentation as Source for Potentially Probiotic Yeasts.

One approach towards maintaining healthy microbiota in the human gastrointestinal tract is through the consumption of probiotics. Until now, the majority of probiotic research has focused on probiotic bacteria, but over the last few years more and more studies have demonstrated the probiotic properties of yeast, and also of species besides the well-studied Saccharomyces cerevisiae var. boulardii. Probiotic strains have to present the ability to survive in harsh conditions of the host body, like the digestive tract. Must fermentation might be an example of a similar harsh environment. In the presented study, we examined the probiotic potential of 44 yeast strains isolated from Polish wines. The tested isolates belonged to six species: Hanseniaspora uvarum, Pichia kluyveri, Metschnikowia pulcherrima, Metschnikowia ziziphicola, Saccharomyces cerevisiae and Starmerella bacillaris. The tested strains were subjected to an assessment of probiotic properties, their safety and their other properties, such as enzymatic activity or antioxidant properties, in order to assess their potential usefulness as probiotic yeast candidates. Within the most promising strains were representatives of three species: H. uvarum, M. pulcherrima and S. cerevisiae. H. uvarum strains 15 and 16, as well as S. cerevisiae strain 37, showed, among other features, survivability in gastrointestinal tract conditions exceeding 100%, high hydrophobicity and autoaggregation, had no hemolytic activity and did not produce biogenic amines. The obtained results show that Polish wines might be a source of potential probiotic yeast candidates with perspectives for further research.

To each their own: Delving into the vitaminic preferences of non-Saccharomyces wine yeasts.

Considering the growing interest in non-Saccharomyces wine yeasts, and notably in the context of mixed fermentations with S. cerevisiae, understanding their nutritional behaviors is essential to ensure better management of these fermentations. The vitaminic consumption of three non-Saccharomyces yeasts (Starmerella bacillaris, Metschnikowia pulcherrima and Torulaspora delbrueckii) was investigated during their growth in wine-like conditions, providing initial evidence that they consume different vitamers. The vitamin consumption profiles during their growth highlighted releases of certain vitamers by the yeasts before re-assimilation, strongly suggesting the existence of synthesis pathways. Not only did the essential character of vitamin B1, in particular, appear to be a trait common to these yeasts, since all its vitamers are consumed, this investigation also provided evidence of the existence of species-dependent preferences for their vitaminic sources. These different behaviors were quite striking in certain vitamers, as was observed in nicotinamide: while it was consumed by T. delbrueckii, it was left untouched by S. bacillaris and produced by M. pulcherrima during growth. Furthermore, this offers grounds for further investigation into these yeasts' requirements, and provides the first tool for managing vitamin resources during mixed fermentations with S. cerevisiae, and for preventing nutritive deficiencies from occurring.

The Flavor Chemistry of Fortified Wines-A Comprehensive Approach.

For centuries, wine has had a fundamental role in the culture and habits of different civilizations. Amongst numerous wine types that involve specific winemaking processes, fortified wines possess an added value and are greatly honored worldwide. This review comprises the description of the most important characteristics of the main worldwide fortified wines-Madeira, Port, Sherry, Muscat, and Vermouth-structured in three parts. The first part briefly describes the chemistry of wine flavor, the origin of typical aroma (primary, secondary and tertiary), and the influencing parameters during the winemaking process. The second part describes some specificities of worldwide fortified wine, highlighting the volatile composition with particular emphasis on aroma compounds. The third part reports the volatile composition of the most important fortified wines, including the principal characteristics, vinification process, the evolution of volatile organic compounds (VOCs) during the aging processes, and the most important odor descriptors. Given the worldwide popularity and the economic relevance of fortified wines, much research should be done to better understand accurately the reactions and mechanisms that occur in different stages of winemaking, mainly during the oxidative and thermal aging.

Microbial Resources as a Tool for Enhancing Sustainability in Winemaking.

In agriculture, the wine sector is one of the industries most affected by the sustainability issue. It is responsible for about 0.3% of annual global greenhouse gas emissions from anthropogenic activities. Sustainability in vitiviniculture was firstly linked to vineyard management, where the use of fertilizers, pesticides and heavy metals is a major concern. More recently, the contribution of winemaking, from grape harvest to bottling, has also been considered. Several cellar processes could be improved for reducing the environmental impact of the whole chain, including microbe-driven transformations. This paper reviews the potential of microorganisms and interactions thereof as a natural, environmentally friendly tool to improve the sustainability aspects of winemaking, all along the production chain. The main phases identified as potentially interesting for exploiting microbial activities to lower inputs are: (i) pre-fermentative stages, (ii) alcoholic fermentation, (iii) stage between alcoholic and malolactic fermentation, (iv) malolactic fermentation, (v) stabilization and spoilage risk management, and (vi) by-products and wastewater treatment. The presence of proper yeast or bacterial strains, the management and timing of inoculation of starter cultures, and some appropriate technological modifications that favor selected microbial activities can lead to several positive effects, including (among other) energy savings, reduction of chemical additives such as sulfites, and reuse of certain residues.

Alternative Woods in Enology: Characterization of Tannin and Low Molecular Weight Phenol Compounds with Respect to Traditional Oak Woods. A Review.

Wood is one of the most highly valued materials in enology since the chemical composition and sensorial properties of wine change significantly when in contact with it. The need for wood in cooperage and the concern of enologists in their search for new materials to endow their wines with a special personality has generated interest in the use of other Quercus genus materials different from the traditional ones (Q. petraea, Q. robur and Q. alba) and even other wood genera. Thereby, species from same genera such as Q. pyrenaica Willd., Q. faginea Lam., Q. humboldtti Bonpl., Q. oocarpa Liebm., Q. stellata Wangenh, Q. frainetto Ten., Q. lyrata Walt., Q. bicolor Willd. and other genera such as Castanea sativa Mill. (chestnut), Robinia pseudoacacia L. (false acacia), Prunus avium L. and P. cereaus L. (cherry), Fraxinus excelsior L. (European ash) and F. americana L. (American ash) have been studied with the aim of discovering whether they could be a new reservoir of wood for cooperage. This review aims to summarize the characterization of tannin and low molecular weight phenol compositions of these alternative woods for enology in their different cooperage stages and compare them to traditional oak woods, as both are essential to proposing their use in cooperage for aging wine.

An optimized method for synthesis and purification of 1,1,6-trimethyl-1,2-dihydronaphthalene (TDN).

1,1,6-Trimethyl-1,2-dihydronaphthalene (TDN), an aroma compound present in wine, is used for sensory and physicochemical analyses. Therefore, synthesis of TDN of high purity is required for these purposes. Optimization of TDN synthesis in order to facilitate its subsequent purification was described. As a result, ≥99.5 % of TDN purity was reached. •The possibility of using both α-ionone and ß-ionone as starting substances was demonstrated•Modifications of the use of reagents in the second and third steps of TDN synthesis were proposed.

Application of nanotechnology based-biosensors in analysis of wine compounds and control of wine quality and safety: A critical review.

Nanotechnology is one of the most promising future technologies for the food industry. Some of its applications have already been introduced in analytical techniques and food packaging technologies. This review summarizes existing knowledge about the implementation of nanotechnology in wine laboratory procedures. The focus is mainly on recent advancements in the design and development of nanomaterial-based sensors for wine compounds analysis and assessing wine safety. Nanotechnological approaches could be useful in the wine production process, to simplify wine analysis methods, and to improve the quality and safety of the final product.

The impacts of Schizosaccharomyces on winemaking.

In the past century, yeasts from the genus Saccharomyces represented the only option in fermentation industries, such as winemaking, to produce wine, beer, and other fermented products. However, other genera are currently emerging to solve challenges in modern enology. Schizosaccharomyces pombe is showing promising results in solving specific challenges in northern, cool viticulture regions with highly acidic wines by deacidifying these wines through its malic acid metabolism. In addition, this microorganism is considered beneficial in warm growing regions with challenges such as the control of wine food safety problems such as the presence of biogenic amines, ochratoxin A, or ethyl carbamate. Indeed, the genus Schizosaccharomyces positively influences other important wine quality parameters, such as color and polysaccharide content. However, the main challenge of using this genus remains the selection of proper strains that alleviate problems such as the production of high acetate concentrations. Industries other than wine production such as ginger fermentation, apple wine, Kei-apple fermentation, plum wine, sparkling wine, and bilberry fermentation industries have also started to study Schizosaccharomyces species as an alternative tool for solving specific related problems. The review discusses the influence of Schizosaccharomyces on different fermentation quality parameters and its main applications in different industries.

Dissection of the molecular bases of genotype x environment interactions: a study of phenotypic plasticity of Saccharomyces cerevisiae in grape juices.

BACKGROUND: The ability of a genotype to produce different phenotypes according to its surrounding environment is known as phenotypic plasticity. Within different individuals of the same species, phenotypic plasticity can vary greatly. This contrasting response is caused by gene-by-environment interactions (GxE). Understanding GxE interactions is particularly important in agronomy, since selected breeds and varieties may have divergent phenotypes according to their growing environment. Industrial microbes such as Saccharomyces cerevisiae are also faced with a large range of fermentation conditions that affect their technological properties. Finding the molecular determinism of such variations is a critical task for better understanding the genetic bases of phenotypic plasticity and can also be helpful in order to improve breeding methods. RESULTS: In this study we implemented a QTL mapping program using two independent cross (~ 100 progeny) in order to investigate the molecular basis of yeast phenotypic response in a wine fermentation context. Thanks to whole genome sequencing approaches, both crosses were genotyped, providing saturated genetic maps of thousands of markers. Linkage analyses allowed the detection of 78 QTLs including 21 with significant interaction with the environmental conditions. Molecular dissection of a major QTL demonstrated that the sulfite pump Ssu1p has a pleiotropic effect and impacts the phenotypic plasticity of several traits. CONCLUSIONS: The detection of QTLs and their interactions with environment emphasizes the complexity of yeast industrial traits. The validation of the interaction of SSU1 allelic variants with the nature of the fermented juice increases knowledge about the impact of the sulfite pump during fermentation. All together these results pave the way for exploiting and deciphering the genetic determinism of phenotypic plasticity.

Physicochemical and sensory characteristics of fine sparkling red wines produced at different maceration lengths in the south of Brazil / Características físico-químicas e sensoriais de vinhos espumantes finos tintos produzidos a partir de diferentes períodos de maceração no sul do Brasil

Maceration is the step of the vinification process in which phenolic and aromatic compounds are transferred to wine. This study aimed at producing fine sparkling red wines by testing different grape varieties and maceration lengths. Grapes underwent maceration for 24 hours (Very Short Maceration ­ VSM) and for 48 hours (Short Maceration ­ SM). Sparkling wines were produced by the traditional method and analyses were carried out in the must, base wines and sparkling wines. Analyzes of minerals, volatile compounds and physicochemicals related to total soluble solids (TSS), Volatile Acidity (VA); Free Sulfur Dioxide (Free SO2); Total Sulfur Dioxide (Total SO2); Total Titratable Acidity (TTA); Fixed Acidity (FA); Hydrogenionic Potential (pH); Alcoholic Content (AC); Reduced Dry Extract (RDE); Total Tannins (TT); Total Anthocyanins (TA); Total Polyphenol Content (TPC); Total Color Intensity (TCI). In addition, during the tasting, a quantitative and descriptive record was distributed to the researchers to characterize the wines in relation to color, perlage, aroma, flavor, main descriptor of the aroma and main general adjective. The sparkling wines which had the best evaluations at different maceration lengths were the following: sparkling wine 100% Teroldego (SM) and sparkling wine 62.5% Teroldego, 18.75% Merlot and 18.75% Pinot (SM). Both short maceration (48 hours) and the Teroldego variety were the vinification parameters which provided the best olfactory-gustatory and color characteristics to the sparkling wines under study. All sparkling wines had enological potential to be vinified in red. Maturation and maceration processes under evaluation produced the typical freshness of sparkling wines and the desired red color.

A maceração é a etapa da vinificação na qual os compostos fenólicos e aromáticos são transferidos ao vinho. O objetivo deste trabalho foi produzir espumantes finos tintos testando a variedade de uva e a duração da maceração. As uvas sofreram maceração por 24 horas (Maceração Muito Curta - MMC) e por 48 horas (Maceração Curta - MC). Os espumantes foram produzidos com o método tradicional e as análises realizadas nos mostos, vinhos base e espumantes. Foram realizadas análises de minerais, de compostos voláteis e físico-químicas relacionadas a sólidos solúveis totais (SST), acidez volátil (AV), acidez total (AcT), dióxido de enxofre livre (SO2L) e total (SO2T), acidez fixa (AF), potencial hidrogeniônico (pH), teor alcoólico (TA), extrato seco (ES), extrato seco reduzido (ESR), índice de polifenóis totais (IPT), antocianinas totais (AT), taninos totais (TT) e intensidade total da cor (ITC). Além disso, durante a degustação, uma ficha quantitativa e descritiva foi distribuída aos pesquisadores para caracterizar os vinhos em relação à cor, perlage, aroma, sabor, principal descritor do aroma e principal adjetivo geral. Nas diferentes macerações, os espumantes que obtiveram melhores avaliações foram: 100% Teroldego (MC) e 62,5% Teroldego, 18,75% Merlot e 18,75% Pinot Noir (MC). Indicando que a maceração curta e a variedade Teroldego foram os parâmetros de vinificação que proporcionaram melhores características olfato-gustativas e de coloração aos espumantes estudados. Excetuando-se o espumante 100% Merlot (MC), todos demonstraram possuir potencial enológico para serem vinificados em tinto e as maturações e macerações testadas produziram o frescor característico dos espumantes e a coloração tinta desejada.

Glycolytic Functions Are Conserved in the Genome of the Wine Yeast Hanseniaspora uvarum, and Pyruvate Kinase Limits Its Capacity for Alcoholic Fermentation.

Hanseniaspora uvarum (anamorph Kloeckera apiculata) is a predominant yeast on wine grapes and other fruits and has a strong influence on wine quality, even when Saccharomyces cerevisiae starter cultures are employed. In this work, we sequenced and annotated approximately 93% of the H. uvarum genome. Southern and synteny analyses were employed to construct a map of the seven chromosomes present in a type strain. Comparative determinations of specific enzyme activities within the fermentative pathway in H. uvarum and S. cerevisiae indicated that the reduced capacity of the former yeast for ethanol production is caused primarily by an ∼10-fold-lower activity of the key glycolytic enzyme pyruvate kinase. The heterologous expression of the encoding gene, H. uvarumPYK1 (HuPYK1), and two genes encoding the phosphofructokinase subunits, HuPFK1 and HuPFK2, in the respective deletion mutants of S. cerevisiae confirmed their functional homology.IMPORTANCEHanseniaspora uvarum is a predominant yeast species on grapes and other fruits. It contributes significantly to the production of desired as well as unfavorable aroma compounds and thus determines the quality of the final product, especially wine. Despite this obvious importance, knowledge on its genetics is scarce. As a basis for targeted metabolic modifications, here we provide the results of a genomic sequencing approach, including the annotation of 3,010 protein-encoding genes, e.g., those encoding the entire sugar fermentation pathway, key components of stress response signaling pathways, and enzymes catalyzing the production of aroma compounds. Comparative analyses suggest that the low fermentative capacity of H. uvarum compared to that of Saccharomyces cerevisiae can be attributed to low pyruvate kinase activity. The data reported here are expected to aid in establishing H. uvarum as a non-Saccharomyces yeast in starter cultures for wine and cider fermentations.

A taste of science: Making the subjective objective in the California wine world.

This article is about the relationship between the categories of the subjective and the objective in the late 20th-century California wine world, about attempts to transform 'soft' subjective judgments into 'hard' objective descriptions and evaluations, and about the role of both sensory science and chemistry in such attempts. It focuses on research done at the University of California, Davis, from about the 1950s to the 1980s by the enologist Maynard Amerine, his co-workers, and successors. It suggests ways in which these materials might prompt attention to the role of subjective judgment and the marketplace in other forms of late modern science.

The taste machine: Sense, subjectivity, and statistics in the California wine world.

This article is about mid-20th-century attempts to turn subjective judgments about the quality and composition of wine into objective knowledge. It focuses on the research of Maynard Amerine at the University of California, Davis, and his project to formalize the procedures of sensory evaluation. Using controlled experimental conditions, Amerine and colleagues transcribed judgments about taste into numbers that could then be aggregated and analyzed statistically. Through such techniques, they claimed to be able to turn subjectivities into objectivities, rendering private taste sensations into reliable and stable facts about objects in the world.

Characterization and Comparison of Wine Lees by Liquid Chromatography-Mass Spectrometry in High-Resolution Mode.

Wine lees from 11 different wineries pertaining to two denominations of origin in Spain (La Rioja and Ribera del Duero) have been characterized in this research by LC-MS/MS in high-resolution mode. For this purpose, the wine lees were separated into the liquid phase (imbibed wine from lees) and the solid residue, which was dried and subjected to solid-liquid extraction assisted by microwaves (dried lees). Both fractions were separately analyzed and the fractions from the 11 wineries compared to find similarity in their patterns. The statistical analysis enabled both differences and common aspects in the composition of imbibed wine from lees and dried lees from all wineries to be found. MS/MS tentative identification of representative compounds in each fraction revealed the varied composition of wine lees with special emphasis on flavonoids such as quercetin, myricetin, and malvidin 3-galactoside, identified in extracts of dried lees, or other compounds such as kaempferol 3-(2',3'-diacetylrhamnoside)-7″-rhamnoside, aminocaproic acid, and citric acid, exclusively identified in imbibed wine from lees. The adsorbent capacity of the solid residue justified the high concentration of phenolic compounds in the extracts from solid lees. The differences found in the composition of the two phases support the separated exploitation of them.

The Genetics of Non-conventional Wine Yeasts: Current Knowledge and Future Challenges.

Saccharomyces cerevisiae is by far the most widely used yeast in oenology. However, during the last decade, several other yeasts species has been purposed for winemaking as they could positively impact wine quality. Some of these non-conventional yeasts (Torulaspora delbrueckii, Metschnikowia pulcherrima, Pichia kluyveri, Lachancea thermotolerans, etc.) are now proposed as starters culture for winemakers in mixed fermentation with S. cerevisiae, and several others are the subject of various studies (Hanseniaspora uvarum, Starmerella bacillaris, etc.). Along with their biotechnological use, the knowledge of these non-conventional yeasts greatly increased these last 10 years. The aim of this review is to describe the last updates and the current state-of-art of the genetics of non-conventional yeasts (including S. uvarum, T. delbrueckii, S. bacillaris, etc.). We describe how genomics and genetics tools provide new data into the population structure and biodiversity of non-conventional yeasts in winemaking environments. Future challenges will lie on the development of selection programs and/or genetic improvement of these non-conventional species. We discuss how genetics, genomics and the advances in next-generation sequencing will help the wine industry to develop the biotechnological use of non-conventional yeasts to improve the quality and differentiation of wines.

Discrimination of brazilian red varietal wines according to their sensory descriptors / Discriminação de vinhos tintos Brasileiros varietais de acordo com suas características sensoriais

The purpose of this paper was to establish the sensory characteristics of wines made from old and newly introduced red grape varieties. To attain this objective, 16 Brazilian red varietal wines were evaluated by a sensory panel of enologists who assessed wines according to their aroma and flavor descriptors. A 90 mm unstructured scale was used to quantify the intensity of 26 descriptors, which were analyzed by means of the Principal Component Analysis (PCA). The PCA showed that three important components represented 74.11 percent of the total variation. PC 1 discriminated Tempranillo, Marselan and Ruby Cabernet wines, with Tempranillo being characterized by its equilibrium, quality, harmony, persistence and body, as well as by, fruity, spicy and oaky characters. The other two varietals were defined by vegetal, oaky and salty characteristics; PC 2 discriminated Pinot Noir, Sangiovese, Cabernet Sauvignon and Arinarnoa, where Pinot Noir was characterized by its floral flavor; PC 3 discriminated only Malbec, which had weak, floral and fruity characteristics. The other varietal wines did not show important discriminating effects.

Conduziu-se este trabalho, com o objetivo de determinar as características sensoriais de vinhos tintos brasileiros elaborados com cultivares de uva introduzidos no país há algum tempo e outros, mais recentemente. Para tanto, as características de 16 vinhos tintos varietais brasileiros foram determinadas por um painel formado por enólogos que avaliaram os vinhos de acordo com suas características de aroma e sabor. Isso foi realizado utilizando-se uma escala não estruturada de 90 mm, a qual apresentava a intensidade de 26 descritores que foram analisados pela Análise de Componentes Principais (ACP). A ACP mostrou três importantes componentes, os quais representaram 74,11 por cento da variação total. De fato, o CP 1 discriminou os vinhos Tempranillo, Marselan e Ruby Cabernet, o primeiro deles sendo caracterizado pelos descritores equilíbrio, qualidade, harmonia, persistência, corpo, frutado, especiaria e carvalho, e, os outros dois, pelos descritores vegetal, carvalho e salgado; o CP 2 discriminou os vinhos Pinot Noir, Sangiovese, Cabernet Sauvignon e Arinarnoa, tendo sido o Pinot Noir caracterizado por seu sabor floral; o CP 3 discriminou o vinho Malbec, que teve descritores florais e frutados fracos. Os demais vinhos varietais não apresentaram efeito discriminatório importante.

Desfolha parcial em videiras e seus efeitos em uvas e vinhos Cabernet Sauvignon da região da Campanha do Rio Grande do Sul, Brasil / Partial de foliation on vines and its effects on Cabernet Sauvignon grapes and wines from the southwest of Rio Grande do Sul, Brazil

A desfolha no vinhedo tem como principais objetivos aumentar a radiação solar e a aeração na região dos frutos, para melhorar a coloração e a maturação das uvas tintas, além de reduzir a incidência de podridões, visando, com isso, obter vinhos de qualidade superior. O principal objetivo deste trabalho foi avaliar o efeito da desfolha nos parâmetros físico-químicos das uvas e dos vinhos Cabernet Sauvignon de Dom Pedrito, região da Campanha, Rio Grande do Sul (RS). As uvas foram colhidas em março de 2008, sendo provenientes de um vinhedo comercial cultivado em espaldeira. A desfolha foi realizada na base dos ramos, somente no lado que recebe o sol da manhã, com intensidade de aproximadamente 20 por cento, no estádio fenológico grão "ervilha". As microvinificações foram feitas com controle de temperatura, em tanques de vidro em triplicata, com oito dias de maceração. Os resultados mostraram que o tratamento com desfolha apresentou mostos com pH significativamente mais baixo e maior acidez total. As cascas das uvas e os vinhos do tratamento com desfolha apresentaram aumento significativo no teor de polifenóis totais. A desfolha também propiciou vinhos com maior intensidade de cor, antocianinas totais, extrato seco e açúcar redutor, e menor teor de nitrogênio. Nos vinhos, não foram observadas diferenças significativas entre os tratamentos para acidez total e volátil, pH, álcool, densidade, extrato seco reduzido e teor de potássio. Conclui-se que a prática da desfolha em vinhedos da região da Campanha melhora a qualidade dos vinhos.

The practice of partial defoliation in vineyards has as main objectives increase sunlight and ventilation for the fruit, aiming to improve color and maturity in red grapes and helping to reduce fungal diseases, which should result in better wine quality. The main aim of this research was to evaluate the effects of partial defoliation on the quality of Cabernet Sauvignon grapes and wines from Dom Pedrito, on the southwest of Rio Grande do Sul state, Brazil. The grapes were harvested in March 2008 from a commercial vineyard planted in the trellis system. The defoliation intensity was of 20 percent and performed only on the side of the vineyard that received the morning sun and when the berry was in the pea-size. The musts were fermented in small lots, in triplicate, with temperature control and remained on the skins for eight days. The results showed that musts of the treatment with defoliation had lower values of pH and higher total acidity. The phenolic content of grape skins and wines was significantly higher for those submitted to defoliation. The defoliation also resulted in wines with greater color intensity, anthocyanins, extract content and reducing sugar, and lower nitrogen content. In wines, there were no significant differences between treatments for total and volatile acidity, pH, alcohol, density, reducing extract and potassium content. As a conclusion, these results might suggest that partial defoliation, as it was done in this vineyard, improves wine quality.

Aplicação de taninos enológicos na elaboração de vinho Cabernet Sauvignon e seus efeitos sobre a qualidade sensorial / Application of enological tannins in the development of Cabert Sauvignon and their effects on the sensory quality

Objetivou-se estudar o efeito do uso de taninos enológicos na composição sensorial do vinho Cabernet Sauvignon. O trabalho foi conduzido em Bento Gonçalves, Rio Grande do Sul (RS), com uvas Cabernet Sauvignon, safra 2004. Trata-se de uma cultivar que se destaca no Brasil pela importância na produção de vinhos tintos de guarda. Porém, em algumas safras, possui dificuldades para uma adequada maturação, o que dificulta a elaboração de vinhos com o perfil sensorial desejado pelos consumidores. Dentre as estratégias para minimizar esse problema, está o manejo do vinhedo, aliado a ajustes tecnológicos nas etapas de elaboração do vinho. Para tal, foram usados taninos de quebracho e castanheira, aplicados em três dosagens (5,0g hl-1, 10,0g hl-1, 20,0g hl-1) e em três momentos de aplicação (maceração, descuba, e após a fermentação malolática). Nos vinhos estabilizados, realizaram-se análises sensoriais, em relação aos atributos ligados aos perfis olfativos e gustativos, com análise de oito descritores olfativos e nove descritores gustativos, além de um conceito geral. Assim, verificou-se que os taninos enológicos imprimiram algumas diferenças, principalmente no perfil aromático dos vinhos, que apresentaram acréscimo de qualidade quando tratados com os taninos enológicos. Da mesma maneira, houve superioridade olfativa e gustativa nos vinhos que receberam tratamentos com taninos na etapa de maceração.

The objective of this research was to study the effect of enological tannins in the sensory composition of the Cabernet Sauvignon wine. The study was conducted in Bento Gonçalves, RS, with Cabernet Sauvignon grapes, harvest 2004. This is a cultivar that stands out in importance in Brazil for the production of red wines. However, in some crops there are difficulties for a proper maturation, which hampers the development of wines with the sensory profile desired by consumers. Among the strategies to minimize this problem there is the management of vineyards, combined with technological adjustments in stages of winemaking. To this end, quebracho and nut tannins were used and applied in three doses (5.0g hl-1, 10.0g hl-1, 20.0g hl-1), with three times of application (maceration, drawing off and after malolactic fermentation). In the stabilized wines, there were sensory analysis, related to the attributes associated with olfactory and taste profiles, with analysis of 8 olfactory descriptors 8 and 9 descriptors taste, besides a general concept. Thus, it was found that the enological tannins enabled some differences, mainly in the volatile profile of wines, which showed an increase of quality when treated with the enological tannins. Similarly, there was superiority smell and taste in the wines that received treatment with tannins in the stage of maceration.

Extrato seco total de vinhos brasileiros: comparação de métodos analíticos / Total dry extract in Brazilian wines: comparison of analytical methods

A legislação brasileira não estabelece limites para o extrato seco total dos vinhos, mas determina valores máximos para a relação álcool em peso/extrato seco reduzido. Até 1985, o extrato seco total era determinado pela pesagem do resíduo seco (método direto), causando problemas de enquadramento à legislação brasileira, principalmente os vinhos tintos finos. A partir de 1986, o extrato seco total passou a ser feito pelo método indireto. Esta metodologia analítica, acrescida da modificação na legislação, alterando os valores máximos da relação álcool em peso/extrato seco reduzido permitiu que, de um modo geral, os vinhos se enquadrassem à legislação. Face a isso, procurou-se comparar os dois métodos para vinhos finos secos e comuns secos e suaves; tintos, brancos e rosados. Os resultados mostraram que o método indireto originou valores do extrato seco total para os vinhos secos, em média 2,1 g/l significativamente maiores em relação ao método direto. Mas o efeito não foi significativo para os suaves. Tendo em vista os valores de extrato seco total dos vinhos encontrados pelo atual método oficial, não se justificam os atuais limites máximos na legislação da relação álcool em peso/extrato seco reduzido, por serem excessivamente elevados.

Brazilian legislation does not establish limits for the total dry extract of wines, but it establishes maximum values for the ratio between weight alcohol and reduced dry extract. Until 1985 the total dry extract was determined by weighting the dry residue (direct method), which caused several problems for the Brazilian legislation mainly for red table wines. From 1986, the total dry extract was measured by indirect method, and the legislation was modifica by increasing the parameters of the ratio between weight alcohol and reduced dry extract. This allowed that the majority of wines were in agreement with the legislation. This work had the objective to compare these two methods for dry vinifera wines, dry and sweet current wines; red, white and rose. Results showed that the indirect method originated significant higher volves (21 g/l in average) for the total dry extract. However, the effect was not significant for sweet wines. Based on the values observed for total dry extract in wines using the offïcial method, there is no justification for the current maximum limits been used for the weight alcohol and reduced dry extract ratio.