Effect of SO2 on the extraction of individual anthocyanins and colored matter of three Portuguese grape varieties during winemaking

Periquita, Tinta Roriz and Tinta Barroca grapes were fermented under standard conditions with 3 levels of SO2 concentration. The anthocyanin monomers were separated by HPCL and identified by DAS on the grape skin extracts. Periquita was the wine with the highest color density and the higher content in total anthocyanins. Malvidin 3-glucoside, peonidin 3-glucoside and petunidin 3-glucoside were found in largest amounts in Periquita wines, while delphinidin 3-gucoside and malvidin 3-glucoside-p-coumarate were present in higher concentrations in Tinta Barroca wines. Malvidin 3-glucoside acetate and peonidin 3-glucoside coumarate were found in the highest concentration in Tinta Roriz wines. The influence of SO2 on the extraction of total anthocyanins and the major part of monomeric anthocyanins was very evident, but the rate of the extraction depends also on the nature of the anthocyanins and the characteristics of each variety. The high concentration of SO2 slowed down the formation of polymeric pigments

Extraction of Some Ellagic Tannins and Ellagic Acid from Oak Wood Chips (Quercus pyrenaica L.) in Model Wine Solutions: Effect of Time, pH, Temperature and Alcoholic Content

The subject of the present work is the study of the influence of pH, temperature, alcoholic content and time on the extraction of some individual ellagic tannins (castalagin, vescalagin, grandinin, roburin D and E) and ellagic acid from oak wood chips (Quercus pyrenaica L.) within model wine solutions. The determination of these compounds by reversed-phase high-performance liquid chromatography (HPLC), after 104 extraction days, enabled us to establish the qualitative and quantitative evolution of each component and the effect of each extraction condition on individual and total ellagic tannins from oak wood chips. Vescalagin and castalagin were the most abundant individual ellagic tannins measured under all extraction conditions. Individual ellagic tannins and ellagic acid increased during the first weeks of extraction, followed by a decrease. Under the extraction conditions examined, temperature was the main factor influencing ellagic tannins and elagic acid evolution. The results suggest that a decrease/degradation of these compounds is less noticeable at low temperatures (12ºC). After 104 extraction days the ellagic tannins content in a model wine solution at 12ºC was higher than the content of ellagic tannins in solutions at 20ºC. On the other hand, the effects of alcoholic content and pH of model wine solutions on the extraction and evolution of the analysed compounds (except for castalagin and vescalagin) seemed to be less important than temperature

Validation and Comparison of Formol and FT-IR Methods for Assimilable Nitrogen in Vine Grapes

In this study, two methods used to evaluate assimilable nitrogen in grape juice were compared, namely:the formol method and the Fοurier-transform mid-infrared (FT-MIR) spectroscopy. At the outset theformol method was validated in the laboratory by determining parameters such as precision, accuracyand trueness. Parallel recovery studies were conducted with a model solution and natural grape juice forammonium and arginine. Average recoveries of ammonium for the formol titration ranged from 77%to 88% and for arginine from 90% to 97%. The repeatability and the intra laboratory reproducibilitywere ±6.4 and ±31.7 (mg/L of nitrogen) respectively. Formol titration was used as the reference methodfor the calibration of FT-MIR spectroscopy to determine the assimilable nitrogen in grape juice. Grapejuice samples (n=71) for 7 red and 7 white varieties from the Lisbon region in Portugal were analyzedsimultaneously by using the formol method and Fοurier-transform mid-infrared (FT-MIR) spectroscopy.The results of this study demonstrated that it is possible to explore the applicability of FT-ÎœIR technologyto detect the assimilable nitrogen in grape juice for quantification purposes. The correlation coefficient(R2=0. 993), standard prediction error (SEP; 6.4 mg/L) and the RPD or standard deviation of the data/standard error of prediction value (Sd/Se; 7.8) proved satisfactory for the calibration of the instrument.In addition, the results obtained by FT-MIR spectroscopy were comparable to those obtained when usingthe reference method

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Effect of Various Proteins on Different Molecular Weight Proanthocyanidin Fractions of Red Wine during Wine Fining

The effect of several proteins on three main wine proanthocyanidin containing fractions with the mean degree of polymerization (mDP) of 1.5 (FI), 3.4 (FII), and 4.9 (FIII) was studied. Although casein and potassium caseinate showed similar molecular weight (MW) distribution, casein decreased the FI fraction more than the twice as effectively as potassium caseinate. A gelatin with a medium MW polydispersion induced a similar decrease (~20%) in all tannin fractions. A gelatin with low MW primarily removed the tannin fractions of lower mDP (FI and FII), while a gelatin with a higher MW had a minor effect (5%) on the fraction of higher mDP (FIII). Neither of the two studied isinglasses reduced the FII fraction. The tannins of FI and FIII were removed by swim bladder isinglass twice as effectively as by fish skin isinglass. For the mDP of fined wines, egg albumin induced a decrease on mDP of 24% for the more polymerized tannin fraction (FIII); although within all assays there was a decrease ranging from 6 to 14%info:eu-repo/semantics/publishedVersio

Influence of Fining and Tartaric Stabilisation Procedures on White Wine Mannoprotein Content

Limpidity is a major quality attribute in white wine appreciation. After alcoholic fermentation and ageing,white wines are normally subjected to protein and tartaric stabilisation, followed by filtration. The impactof bentonite and gelatine fining and cold static tartaric stabilisation on the mannoprotein content of twowhite wines was studied. All treatments promoted a decrease in the content of mannoproteins. Bentonitefining largely affected the mannoproteins with the highest molecular weight, as did cold static tartaricstabilisation and gelatine fining

Chemical and Sensorial Characterization of Tropical Syrah Wines Produced at Different Altitudes in Northeast of Brazil

Over the years, viticulture has expanded to new regions outside the temperate zones, such as Northeast Brazil, India, Thailand, Myanmar, Vietnam, Bangladesh and Venezuela, characterized by the production of tropical wines. It is important for the productive sector to comprehend the effects of grapevine interaction with the characteristics of each new region on wines composition. In this study, the composition of wines of Syrah from two regions with different altitudes in Northeast Brazil were analyzed by different methodologies to characterize chemical compounds as sugar, acids, minerals, phenolics (anthocyanins, flavonols, stilbenes and condensed tannins) and the sensory profile. The wines of the Bahia region (1100 m of altitude) obtained high concentrations for chemical parameters related to color, monomeric anthocyanins, stilbenes and monomeric and oligomeric tannins. Wines of the low altitude region, Pernambuco (350 m of altitude) were characterized by higher concentrations of flavonols (kaempferol, isorhamnetin, quercetin and rutin) and polymerized tannins. The chemical composition of wines from the two studied regions was influenced by altitude. A trend towards higher concentrations in most for phenolic compounds analyzed was observed in wines from the higher altitude region during the two years of study. Regarding the sensory profile, fruity, floral, herbaceous and empyreumatic attributes aromatic obtained highest scores in wines of the 350 m altitude region, the other attributes were dependent on the year of harvest

Estimativa da erosividade nas bacias hidrográficas dos rios Guapi-Macacu e Caceribu.

As perdas de solos ocasionadas por eventos de chuvas não dependem somente da resistência que o solo oferece ao impacto das gotas, mas também da energia cinética da chuva e da intensidade e duração. A influência desses fatores na capacidade da chuva em causar erosão é estimada através de índices de erosividade, sendo mais utilizados dois índices na literatura: EI30 e KE > 25. O presente trabalho teve como objetivo estimar os índices de erosividade com base nos dados pluviométricos de 19 estações e mostrar as distribuições espaciais dos mesmos nas bacias hidrográficas dos rios Guapi- Macacu e Caceribu. Os resultados mostraram que os dois índices apresentaram padrão similar em termos de valores relativos e de distribuição na área de estudo. Os índices apresentaram maiores valores mensais no período de novembro a março que corresponde ao verão, quando é característico ocorrerem chuvas de maiores intensidades, devido ao aumento da temperatura e das movimentações de massas de ar. Ao contrário, os menores valores foram observados nos meses de junho a agosto, período no qual ocorrem chuvas com menores intensidades.bitstream/item/83413/1/BPD-205-Estimativa-erosividade.pd

Chemical and sensorial characterization of tropical syrah wines produced at different altitudes in northeast of the Brazil.

Over the years, viticulture has expanded to new regions outside the temperate zones, such as Northeast Brazil, India, Thailand, Myanmar, Vietnam, Bangladesh and Venezuela, characterized by the production of tropical wines. It is important for the productive sector to comprehend the effects of grapevine interaction with the characteristics of each new region on wines composition. In this study, the composition of wines of Syrah from two regions with different altitudes in Northeast Brazil were analyzed by different methodologies to characterize chemical compounds as sugar, acids, minerals, phenolics (anthocyanins, flavonols, stilbenes and condensed tannins) and the sensory profile. The wines of the Bahia region (1100 m of altitude) obtained high concentrations for chemical parameters related to color, monomeric anthocyanins, stilbenes and monomeric and oligomeric tannins. Wines of the low altitude region, Pernambuco (350 m of altitude) were characterized by higher concentrations of flavonols (kaempferol, isorhamnetin, quercetin and rutin) and polymerized tannins. The chemical composition of wines from the two studied regions was influenced by altitude. A trend towards higher concentrations in most for phenolic compounds analyzed was observed in wines from the higher altitude region during the two years of study. Regarding the sensory profile, fruity, floral, herbaceous and empyreumatic attributes aromatic obtained highest scores in wines of the 350 m altitude region, the other attributes were dependent on the year of harvest

Resposta da casta ‘Syrah’ à monda de cachos

Este trabalho teve por objectivo estudar o efeito da monda de cachos na produção e nas características analíticas das uvas e do vinho, casta ’Syrah’, bem como analisar a vertente económica da operação. Num ensaio realizado no ano de 2007 na região vitícola de Alenquer, Quinta do Pinto, Merceana, comparou-se uma modalidade testemunha não mondada (T) com duas modalidades mondadas, em dois estados fenológicos distintos, bago de ervilha (MBE) e pintor (MP), ambas com a mesma intensidade de monda (50% de cachos removidos). A monda induziu uma redução significativa no rendimento (-36%) e uma melhoria nos parâmetros da qualidade, excepto na acidez total e na tonalidade da cor que apresentaram valores idênticos aos da testemunha não mondada. Destaca-se o efeito positivo da monda no grau alcoólico e nos compostos fenólicos, principalmente nas antocianinas. Os vinhos elaborados a partir das uvas das modalidades mondadas foram significativamente melhor classificados e preferidos em prova organoléptica. O vigor e expressão vegetativa da videira não foram significativamente influenciados pela monda. O efeito da época de monda não foi significativo em qualquer dos parâmetros analisados. A monda aumentou os custos de produção, principalmente quando realizada ao bago de ervilha, sendo uma opção viável em vinhas com produções potenciais elevadas, quando o objectivo é a produção de vinhos de qualidadeinfo:eu-repo/semantics/publishedVersio