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- Enhancement of apparent resistance to ethanol in Lactobacillus hilgardiiPublication . Couto, José António; Pina, Cristina; Hogg, TimThe survival of Lactobacillus hilgardii, a highly ethanol-tolerant organism, after an ethanol challenge at 25% (v/v) for 10 min, increased by several log cycles when cells, grown in the absence of ethanol, were pre-treated with 10% (v/v) ethanol, 15% (v/v) methanol or 2% (v/v) butanol for 4 h. A temperature upshift (25 to 40°C) before ethanol challenge demonstrated a similar enhancement of apparent resistance to ethanol. Ethanol shock enhanced apparent resistance to methanol, butanol and heat challenges. The addition of chloramphenicol to cells prior to any pre-treatment did not significantly diminish the increase in ethanol tolerance, suggesting that de novo protein synthesis is not required for induced tolerance in this organism
- Development of a flow method for monitoring cell membrane damage: application to the study of phosphate release from wine lactic acid bacteriaPublication . Torres, André F.; Mesquita, Paulo A. R.; Tóth, Ildikó V.; Campos, Francisco M.; Couto, José A.; Hogg, Tim; Rangel, António O. S. S.
- Influence of phenolic compounds on glucose and organic acids metabolism of wine lactic acid bacteriaPublication . Bilé, Teresa; Sá, Filipa; Campos, Francisco M.; Figueiredo, Ana R.; Couto, José A.; Hogg, Tim
- Effect of phenolic acids on glucose and malic acid metabolism of Lactobacillus hilgardiiPublication . Campos, F. M.; Couto, J. A.; Hogg, T. A.
- Production of volatile phenols by wine PediococciPublication . Couto, José A.; Campos, Francisco M.; Figueiredo, Ana R.; Hogg, Tim
- The influence of selected oenological practices on the sensory impact of volatile phenols in red winesPublication . Barbosa, Antonina; Hogg, Tim; Couto, José AntónioAims: Volatile phenols (4-ethylphenol and 4-ethylguaiacol) affect wine quality by imparting, above certain concentrations, aroma defects. This work aimed to evaluate the effect of some common oenological practices on the concentration of volatile phenols and the sensory impact of these odour-active compounds in wines. Methods and results: The studied oenological practices were based on the addition of gum arabic, mannoproteins, yeast cell walls, lees, oak chips, dairy cream and potassium caseinate and on the application of a bubbled nitrogen stream. These treatments were applied to naturally contaminated wines containing volatile phenols at concentrations above detection threshold. The treated wines were characterised by chemical and sensory analysis. The most effective treatments in the reduction of the concentration of volatile phenols were the addition of fine lees, cream and potassium caseinate. Apart from being able to partially remove these compounds (approximately 35% removal), fine lees contributed to a greater “freshness” and complexity of the wines. Although the addition of cream did decrease the sensory impact of volatile phenols, it did not benefit the wines as these were strongly marked by dairy aromas. The use of oak chips, although it did not have a notable effect on the removal of volatile phenols, led to a significant reduction in the perception of these compounds.
- Cell membrane damage induced by phenolic acids on wine lactic acid bacteriaPublication . Campos, F. M.; Couto, J. A.; Figueiredo, A. R.; Tóth, I. V.; Rangel, António O. S. S.; Hogg, T. A.
- Determinação potenciométrica de efluxo de potássio em bactérias lácticas do vinho sujeitas a stress químicoPublication . Campos, F. M.; Couto, J. A.; Hogg, T. A.; Rangel, António O. S. S.; Tóth, I. V.
- Cell membrane damage induced by phenolic acids on wine lactic acid bacteriaPublication . Campos, Francisco M.; Couto, José A.; Figueiredo, Ana R.; Tóth, Ildikó V.; Rangel, António O. S. S.; Hogg, Tim