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This study aimed to determine the chemical composition of Eucalyptus staigeriana essential oil (EO) and its effect in vivo against Botrytis cinerea and Colletotrichum acutatum in postharvest of grapes and in a vineyard. Moreover, grapes collected from de field experiments were used to evaluate the impact of the alternative control on the alcoholic fermentation and wine composition. The major compounds of E. staigeriana EO were citral (30.91%), 1,8-cineole (24.59%), and limonene (19.47%). In the postharvest experiment, EO was efficient, reducing the incidence and severity of disease caused by B. cinerea and the incidence of disease caused by C. acutatum, both in preventive and curative treatment. Moreover, this EO reduced the incidence and severity of gray rot caused by B. cinerea and the severity of ripe rot caused by C. acutatum in the field. The alternative control did not significantly influence the alcoholic fermentation and volatile composition of wines, except for the residual presence of 1,8-cineole that can contribute to the aroma complexity of 'Isabella' wine. These results are promising and indicate that E. staigeriana EO might be further investigated as a natural alternative to control fungal rots on grapes.

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The sensory quality of wines is affected by the compounds produced by the action of the yeasts used in alcoholic fermentation. This work aimed at assessing the physicochemical, aromatic and sensory properties of the Riesling Italico white wines produced by using the Saccharomyces and non-Saccharomyces yeasts. The yeasts S. cerevisiae, S. cerevisiae cerevisiae, S. bayanus, Torulaspora delbrueckii and Metschnikowia pulcherrima were inoculated individually into the must. For 10 days, the alcohol was left to ferment in 7 L carboys in triplicate, at 15º C temperature. The standard physicochemical analyses were done and the quality of the wines was determined. The volatile compounds were identified and quantitative descriptive sensory analyses were performed. All the yeasts produced wines with the characteristic alcohol, volatile acidity and residual sugar content as stipulated by the Brazilian legislation. The T. delbrueckii yeast produced high-content phenylethyl acetate, isoamyl acetate and ethyl decanoate wines, of superior olfactory quality and sensory rating.(AU)

Durante a fermentação alcoólica as leveduras produzem compostos que influenciam a qualidade sensorial dos vinhos. O objetivo do trabalho foi avaliar as propriedades físico-químicas, aromáticas e sensoriais do vinho branco da variedade Riesling Italico elaborado a partir de leveduras Saccharomyces e não-Saccharomyces. Foram inoculadas separadamente no mosto as leveduras S. cerevisiae, S. cerevisiae cerevisiae, S. bayanus, Torulaspora delbrueckii e Metschnikowia pulcherrima. A fermentação alcoólica ocorreu em garrafões com 7 L de mosto, em triplicata, por 10 dias a 15 ºC. Foram realizadas análises físico-químicas padrão e de identificação da qualidade dos vinhos, além das análises de compostos voláteis e sensorial descritiva quantitativa. Todas as leveduras produziram vinhos com teores de álcool, acidez volátil e açúcar residual de acordo com a legislação. A levedura T. delbrueckii produz vinhos com concentrações elevadas de acetato de feniletila, acetato de isoamila e decanoato de etila, resultando em boa qualidade olfativa e avaliação sensorial.(AU)

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ABSTRACT: The sensory quality of wines is affected by the compounds produced by the action of the yeasts used in alcoholic fermentation. This work aimed at assessing the physicochemical, aromatic and sensory properties of the 'Riesling Italico' white wines produced by using the Saccharomyces and non-Saccharomyces yeasts. The yeasts S. cerevisiae, S. cerevisiae cerevisiae, S. bayanus, Torulaspora delbrueckii and Metschnikowia pulcherrima were inoculated individually into the must. For 10 days, the alcohol was left to ferment in 7 L carboys in triplicate, at 15º C temperature. The standard physicochemical analyses were done and the quality of the wines was determined. The volatile compounds were identified and quantitative descriptive sensory analyses were performed. All the yeasts produced wines with the characteristic alcohol, volatile acidity and residual sugar content as stipulated by the Brazilian legislation. The T. delbrueckii yeast produced high-content phenylethyl acetate, isoamyl acetate and ethyl decanoate wines, of superior olfactory quality and sensory rating.

RESUMO: Durante a fermentação alcoólica as leveduras produzem compostos que influenciam a qualidade sensorial dos vinhos. O objetivo do trabalho foi avaliar as propriedades físico-químicas, aromáticas e sensoriais do vinho branco da variedade Riesling Italico elaborado a partir de leveduras Saccharomyces e "não-Saccharomyces". Foram inoculadas separadamente no mosto as leveduras S. cerevisiae, S. cerevisiae cerevisiae, S. bayanus, Torulaspora delbrueckii e Metschnikowia pulcherrima. A fermentação alcoólica ocorreu em garrafões com 7 L de mosto, em triplicata, por 10 dias a 15 ºC. Foram realizadas análises físico-químicas padrão e de identificação da qualidade dos vinhos, além das análises de compostos voláteis e sensorial descritiva quantitativa. Todas as leveduras produziram vinhos com teores de álcool, acidez volátil e açúcar residual de acordo com a legislação. A levedura T. delbrueckii produz vinhos com concentrações elevadas de acetato de feniletila, acetato de isoamila e decanoato de etila, resultando em boa qualidade olfativa e avaliação sensorial.

RESUMO

BACKGROUND: Essential oils (EOs) are volatile natural compounds produced by plant secondary metabolism, and some of them exhibit antimicrobial activity. The objective of the present study was to determine the chemical composition the EOs of Eucalyptus staigeriana and Eucalyptus globulus, and their effect in vitro and in vivo against Botrytis cinerea and Colletotrichum acutatum, the most important fungal rot diseases of grapes. Moreover, grapes collected from field experiments were used to evaluate the impact of the alternative control on the alcoholic fermentation and wine composition. RESULTS: The major compound of E. staigeriana EO were citral 30.91% (19.74% geranial, 11.17% neral), 1.8-cineole (24.59%) and limonene (19.47%), while 1.8-cineole represented 68.26% of E. globulus EO. The two EOs showed in vitro antifungal activity against both pathogens. Eucalyptus staigeriana EO exhibited the highest activity inhibiting mycelial growth (MG) and conidial germination at 0.5 µL mL-1 . Moreover, this EO was able to reduce the incidence and severity of grey rot caused by B. cinerea and the severity of ripe rot caused by C. acutatum The alternative control did not significantly influence alcoholic fermentation, the physicochemical characteristics, and the volatile composition of wines. CONCLUSION: These results are promising and indicate that E. staigeriana EO might be further investigated as a natural alternative for the control of fungal rots on wine grapes. © 2019 Society of Chemical Industry.

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We present a method that can differentiate between the varieties of grapes and the vintages of wines and show the relationship between the grapes, the wine and the geographic location. The place of origin and its geographic and climatic characteristics were determined by the isotopic ratios, (13)C/(12)C of the ethanol and (18)O/(16)O of the water content of wine (wine water), for southern Brazil wines. The producing subregions of Pinto Bandeira, Vale dos Vinhedos and Nova Pádua showed differences in the temperature, rainfall and humidity conditions used for the production under microvinification conditions of Merlot and Cabernet Sauvignon varieties, in the harvests of 2005 and 2006. An isotope ratio mass spectrometer coupled to an elemental analyzer was used to measure the (13)C/(12)C of ethanol and the (18)O/(16)O of wine water. Regardless of the grape variety used, it was possible to determine the subregion through measurement of the δ(18)O values in both harvests. The altitudes of the different subregions led to statistical differences and demonstrated an influence mainly on the δ(18)O values of wine water. The δ(18)O value of wine water was determined to be more selective for the determination of the cultivation subregions than the δ(13)C value of the ethanol. The altitude and latitude influenced mainly the δ (18)O values of wine water and the ethanol. The climatic influences are more noteworthy in distinguishing the year of the harvest than the cultivation subregion.

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