Mannoprotein-mediated modulation of red wine sensory quality and color stability: a comprehensive study

This PhD research investigated the use of mannoproteins to improve red wine quality (sensorial and color stability), particularly for short-aged commercial wines. It compared two approaches: using yeast strains that overproduce mannoproteins and adding commercial mannoprotein preparations. The study found that overproducing yeast strains were not particularly effective or useful in improving wine quality in this type of vinification. In contrast, commercial mannoproteins, in particular MP4, effectively affect astringency by improving softness and are able to increase colloidal color stability, due to their particular physical and chemical characteristics and to the understanding of their application. These improvements were related to interactions with tannins and mannoproteins, and not simply to tannin-mannoprotein precipitation. The research also developed a model to predict wine saliva precipitation index (astringency) based on various factors, including polysaccharides (of which mannoproteins are an important part). This model highlights the importance of a comprehensive approach to understanding and managing astringency in wine. Overall, this research provides valuable tools for winemakers to manage red wine quality and counteract the effects of climate change and adapt to consumer preferences, through conscientious use of specific oenological practices related to mannoproteins.