Sistema team groupware

Orientador: Dieval GuizeliniMonografia (graduação) - Universidade Federal do Paraná, Escola Técnica, Curso de Tecnologia em InformáticaInclui bibliografi

Sistema team groupware

Orientador: Dieval GuizeliniMonografia (graduação) - Universidade Federal do Paraná, Escola Técnica, Curso de Tecnologia em InformáticaInclui bibliografi

Oxygen consumption and development of volatile sulfur compounds during bottle aging of two Shiraz wines. influence of pre- and postbottling controlled oxygen exposure

The evolution of different volatile sulfur compounds (VSCs) during bottle maturation of two Shiraz wines submitted to controlled oxygen exposure prior to bottling (through micro-oxygenation, MOX) and postbottling (through the closure) was investigated. H2S, methyl mercaptan (MeSH), and dimethyl sulfide (DMS) were found to increase during aging. Lower postbottling oxygen exposure, as obtained by different degrees of oxygen ingress through the closure, resulted in increased H2S and methyl mercaptan. In one wine MOX increased the concentration of H2S and methyl mercaptan during maturation. Dimethyl disulfide and DMS were not affected by any form of oxygen exposure. Overall, postbottling oxygen had a stronger influence than MOX on the evolution of VSCs. Data suggest that dimethyl disulfide was not a precursor to methyl mercaptan during bottle maturation. For the two wines studied, a consumption of oxygen of 5 mg/L over 12 months was the most effective oxygen exposure regimen to decrease accumulation of MeSH and H2S during bottle aging. \ua9 2012 American Chemical Society

Impact of headspace oxygen and closure on sulfur dioxide, color, and hydrogen sulfide levels in a Riesling wine

Following an experimental design replicating typical winery conditions, a Riesling wine was bottled with different headspace oxygen levels and sealed with either a coextruded closure or a screwcap to investigate the impact of headspace oxygen and closure oxygen transfer rate on wine evolution. Using luminescence technology, dissolved oxygen and headspace oxygen, as well as oxygen ingress through the closure, were monitored during 24 months of bottle storage. Under typical winery conditions, headspace oxygen introduced at bottling was found to be a major component of oxygen in bottled wine. Headspace oxygen at bottling influenced loss of sulfur dioxide during bottle storage, being the main cause of sulfur dioxide decline during the first four months after bottling in 375 mL bottles. The loss of sulfur dioxide was not correlated with the evolution of dissolved oxygen, but with the total amount of oxygen consumed by the wine. After 24 months in the bottle, color differences due to different headspace oxygen and closure oxygen transfer rate were generally minor. Conversely, differences in closure oxygen transfer rate were responsible for significant differences in the final concentration of the off-odor compound hydrogen sulfide, with screwcap generally associated with higher levels of this compound. Even if less significantly, the amount of oxygen present in the headspace at bottling also had an effect on final hydrogen sulfide, with higher concentrations observed in wines bottled with lower headspace oxygen. © 2011 by the American Society for Enology and Viticulture. All rights reserved