Desarrollo de nuevos productos microbiológicos y ecológicos de alto valor añadido dirigidos al sector vitivinícola (Microecolev)

Resumen

Spain has established itself as the third-largest wine producer worldwide in 2020. A great technological development has been promoted in the wine sector, which has great economic and social weight in the Autonomous Community of Navarra and in Spain. Currently, the production of wine is carried out under exhaustive control of the winemaking processes, where increasingly complex techniques are used to produce higher quality wines. Therefore, the overall objective of this work has been the development of new products for the wine sector to improve the quality of the wine. The study of products obtained from yeast and lactic acid bacteria has been considered to solve the technological problems that currently occur in winemaking, such as reducing astringency, promoting bacterial growth for malolactic fermentation, inhibiting the development of contaminating microorganisms, preventing wine oxidation or clarifying wine with own natural products. The products have been obtained from inactivated cells, called "lysates", or from the growth of yeasts and lactic acid bacteria typical of grapes. The first specific objective has been to select and develop a cell disruption method for the production of lactic bacteria and yeast lysates, as well as their characterization. A heat treatment method has been developed that produces stable inactivated cells and is applicable at the industrial level. The lysates have been characterized according to their carbohydrates and protein concentration. The second specific objective was to study the carotenogenic and antioxidant capacity of endogenous wine yeasts. The ability to produce carotenoids of twelve yeasts have been studied. Out of all these, a yeast lysate presented a higher concentration of carotenoids, although the lysates of the same species have shown greater capacity to stabilize DPPHº and ABTSº+ radicals. Three lysates have the highest protective capacity against oxidation. The third specific objective has been to study the reduction of wine astringency through treatment with lysed cells of yeasts other than Saccharomyces cerevisiae, and with lysed cells of lactic acid bacteria. Treatments with bacterial and yeast lysates have improved the astringency reduction results obtained with commercial mannoproteins, showing a greater affinity for tannins than the yeast lysates. The potential Z+ of a lysate has a more negative charge than yeast lysates, as well as a smaller particle size, which makes it a more adequate candidate for polymerizing the tannins responsible for wine astringency due to its increased ability to form colloids. The lactic acid bacteria lysate has been selected for its development as a commercial product (ASTRIBAL) and its patent is currently pending (P202030524). The fourth specific objective has been to evaluate the ability to stimulate malolactic fermentation and to shorten its time by treating wine with lysates in the inoculation phase of lactic bacteria. A lysate, added during inoculation of Oenococcus oeni, increases its growth capacity and reduces the time of malolactic fermentation. In the fifth specific objective, new strategies against contamination by Brettanomyces have been explored, applying living organisms or products made from them. In relation to the studied yeasts, two yeasts show the ability to synthesize antimicrobial compounds capable of inhibiting the growth of contaminating yeasts of Brettanomyces bruxellensis. The sixth specific objective has been to study yeast flocculation and its activity as a wine clarifier. Out of the yeasts studied, only a yeast has shown a flocculant phenotype, so the objective of isolating a greater variety of yeast strains and species has not been completed, neither has the study of its activity as a wine fining agent. In conclusion, it has been possible to identify certain strains and lysates that allow solving the technological problems that currently occur in winemaking.