Use of non-saccharomyces yeasts to enhance the quality of red wines

Résumé

The use of non-Saccharomyces yeasts in controlled mixed and sequential fermentations is, nowadays, a biotechnological alternative in the production of wines with optimized organoleptic parameters. This optimization would become a differentiator of wines for the costumers. The metabolism of the diverse yeasts species allows the production of fermentative volatiles able to enrich que aroma profile of wines; in the same time, these yeasts contribute to the polymeric reactions and condensation of polyphenols, including anthocyanins, just as they promote the formation of vitisins and vinyl phenolics. Microbiological selection of yeasts, together with good oenological practices during maceration, wine making and wine ageing, will enhance such biotechnological practice. Emerging technologies used in food preservation and conservation, have become useful in the control of microorganisms during the different productive stages of wine making; these technologies would enrich aroma profile, pigments extraction and complexity of wines as an overall result. This thesis work explores the use of non-Saccharomyces yeasts with interest in the formation of pyranoanthocyan and polymeric pigments through pure culture and sequential fermentations. The assessment of the potential these yeasts may have, is achieved by instrumental analysis techniques. On the other hand, sensory analysis is also used to evaluate their impact on the organoleptic parameters of the experimental wines produced.