Characterization of oenological products and commercial yeasts and inactivation of wine yeasts

Identifier:  TFG:2949

Handle: https://hdl.handle.net/20.500.11797/TFG2949

Authors:  Valero Llopico, Carmen

Abstract:
Today, most commercial oenological products are derived from inactive yeasts and are used in the oenological industry to improve the technological processes or the organoleptic characteristics of wines. They are marketed by numerous biotechnology and/or oenological companies under the name of different brands, but information regarding their use and concrete action is very scarce. Therefore, several oenological products and commercial yeasts were taken and the characterization of the lipidic (sterols and fatty acids) and metabolomic profile was carried out by means of gas chromatography with mass spectrometry. The free amine nitrogen fraction was also analysed by derivatising the α-amino acids with a reagent (o-phthalaldehyde/N-acetyl-L-cysteine, (OPA/NAC)). This study tested whether the products differed from each other and whether they provided the same yeast genus or species, or whether the differences were due to changes in yeast growing conditions. Finally, it was found that the oenological products studied are made from one or more strains of Saccharomyces cerevisiae under different culture conditions (medium, oxygen, temperature, etc.), or not. A method was also developed to inactivate commercial Saccharomyces and non-Saccharomyces (Metschnikowia pulcherrima) yeasts as a function of pH and temperature. The results showed that pH was not a valid method to inactivate Saccharomyces yeast, which needed high temperatures (80 - 90°C) for inactivation and non-Saccharomyces yeast showed optimal inactivation at both pH and temperature (70°C).