Study of the production and release of aromas during winemaking carried out by different Saccharomyces species and hybrids

Aroma is one of the most important attributes involved in wine quality. Current trend in winemaking consists of producing wines with different aroma nuances to offer variety of wines to a developing market. Several studies have demonstrated that low temperature fermentations favours aroma synthesis and retention. In this background, new wine yeasts able to perform fermentation at low temperatures improving wine aroma while maintaining good fermentation rates are necessary. This doctoral thesis explores the oenological traits of different Saccharomyces species and hybrids relevant for present-day wine industry, especially regarding aroma production, as well as the molecular bases underneath. This exploration has been possible using different biochemical, analytical chemistry and molecular techniques to perform enzymatic activity detection, aroma profile determination and transcriptome analysis in wine fermentations. Through this doctoral thesis the abilities of different Saccharomyces species and hybrids regarding primary aroma release and secondary aroma production, especially at low temperatures, has been elucidated in order to know the different possibilities that these yeasts offer to create new wines with different aromatic nuances. One of the general conclusions of this doctoral thesis is that production and release of aromas in winemaking depends on the strain carrying out the fermentation process. Nevertheless, sometimes there was a species tendency. On the other hand, the fact that fermentation temperature affects aroma synthesis but not always in the direction to aroma increase has been demonstrated.