La influencia de la tecnología de la vinificación en la microbiología y el desarrollo de la fermentación alcohólica

Abstract

The enological practices used on white wine elaboration introduce some advantages and disadvantages. In order to avoid negative effects some applicable resources have been developed to assure a correct fermentation. The present Thesis studies the effects of these applicable resources on the natural selection of wild Saccharomyces cerevisiae strains that control fermentation. Despite of years of experience has shown that fermentation process and wine quality are significantly affected by the enological characteristics of the Saccharomyces cerevisiae strains driving the fermentation. Different elaborations were carried out during five consecutive vintages since 1994 to 1998, using white grape juice of Viura variety from La Rioja (Spain). The clarification treatments used were clarification by settling and clarification by vacuum filtering. The resources studied: Nitrogen addition (diammonium phosphate and commercial activator with ammonium sulfate), Aeration (by oxygen addition direct and racking), Survival factors addition (Ergosterol), Yeast hulls addition and inert cellulose substrates addition (tree celluloses with different physical characteristics). The more relevant results showed the influence of the type of grape juice clarification treatments on both killer phenomena distribution and wild Saccharomyces cerevisiae strains distribution. These results revealed also the influence of yeast hull and one cellulose on the yeast strains distribution when problematical fermentation conditions were present (high temperature or high number of no-Saccharomyces strains). The fermentation process improved when yeast hulls, inert celluloses substrates, aeration and survival factors were used, however nitrogen addition has been different results.