https://dspace.ifrs.edu.br/xmlui/handle/123456789/348 Thu, 04 Jun 2026 17:59:22 GMT 2026-06-04T17:59:22Z https://dspace.ifrs.edu.br/xmlui/handle/123456789/519 Yeast stress and death caused by the synergistic effect of ethanol and SO2 during the second fermentation of sparkling wines Cisilotto, Bruno; Scariot, Fernando Joel; Schwarz, Luisa Vivian; Rocha, Ronaldo Kauê Mattos; Longaray, Ana Paula; Echeverrigaray, Sergio Problems can often arise at the beginning of the second fermentation (prise de mousse) of sparkling wines, such as no start, a long lag period or slow fermentation. These problems are generally associated with yeast stress when inoculated in a base wine with high ethanol content and low pH. However, few studies focus on sulphites, which are often added to base wines to prevent malolactic fermentation, microbiological instability, and wine oxidation. This study aimed to evaluate the joint effect of ethanol and sulfur dioxide on yeasts during the second fermentation. For this purpose, yeasts (Saccharomyces cerevisiae EC1118) were subjected to ethanol, sulfur dioxide and ethanol/sulfur dioxide at the beginning of fermentation, and their vitality and viability, as well as the accumulation of intracellular reactive oxygen species and intracellular pH, were evaluated by flow cytometry. Furthermore, the expression of genes involved in sulfur transport and metabolism was determined. The results showed high mortality, ROS accumulation and intracellular pH reduction in fermentations with both ethanol and sulfur dioxide. The negative effect of ethanol, sulfur dioxide and ethanol/sulfur dioxide on yeasts was found to be dose-dependent and high in those commonly found in some base wines. Cells treated with ethanol/sulfur dioxide showed over-expression of genes involved in sulphite transport (SUL1 and SUL2), efflux pump (SSU1 and FZF1) and metabolism of sulfur amino acids (MET14). Altogether, our data indicate that ethanol and sulfur dioxide have a synergistic effect on yeasts, which may be the root cause of the problems encountered at the beginning of the second fermentation of sparkling wines, and should thus be seriously taken into consideration by winemakers. Fri, 01 Jan 2021 00:00:00 GMT https://dspace.ifrs.edu.br/xmlui/handle/123456789/519 2021-01-01T00:00:00Z https://dspace.ifrs.edu.br/xmlui/handle/123456789/504 Emissões de particulados em um motor alimentado com misturas biodiesel/Diesel e sob diferentes configurações do sistema de injeção de combustível Sala, José Antonio; Schlosser, José Fernando; Farias, Marcelo Silveira de; Bertollo, Gilvan Moisés; Herzog, Daniela The present study aimed to evaluate the particulate emissions in a Diesel engine with an electronic injection system using different biodiesel blends and variations in the fuel injection point and volume, comparing it with the MAR-1 standard. The particulate emissions are analyzed using a two-factor (12×8) completely randomized design that resulted from the interaction of three biodiesel/Diesel blends, two injection point configurations, two fuel injection volumes and eight crankshaft speeds, with 30 repetitions. According to the results, the particulate emissions meet the requirements established by the MAR-I standard when the engine operates at the original factory settings, fueled with blends containing up to 30% of biodiesel. With the engine angular speed at maximum torque (1,500 rpm), the injection point advanced and the increase in fuel volume, the particulate emissions increased by 115% and 314% for the 10 and 30% biodiesel blends, respectively, regarding the engine operating with the original settings. Sat, 01 Jan 2022 00:00:00 GMT https://dspace.ifrs.edu.br/xmlui/handle/123456789/504 2022-01-01T00:00:00Z