Browsing by Author "Vidal Zuñiga, Josefina Victoria"

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    Effect of Mannoprotein-Producing Yeast on Viscosity and Mouthfeel of Red Wine
    (Multidisciplinary Digital Publishing Institute (MDPI), 2025) Núñez Ferrada, Emerson Andrés; Vidal Zuñiga, Josefina Victoria; Chávez Muñoz, Matías Jesús; Bordeu Schwarze, Edmundo; Osorio, Fernando; Vargas, Sebastian; Hormazabal, Elba; Brossard Aravena, Natalia Daniela
    Mannoproteins enhance wine stability and sensory properties, but their specific role in modulating viscosity and mouthfeel across wine quality levels remains underexplored. This study explores the nuanced impact of various mannoprotein-producing yeast strains on specific mouthfeel sensations, particularly emphasizing viscosity, across Standard and Premium quality tiers of Cabernet Sauvignon commercial wines. The aim was to understand the intricate relationship between yeast-derived mannoproteins and the broader sensory landscape of red wines. The methodology encompasses a comprehensive mannose extraction method, rheological measurements, and sensory Rate-All-That-Apply evaluations, all of which are integrated into a Principal Component Analysis. The results showed slight color variations due to the wine spending one month on lees. A positive correlation was found between mannose content and viscosity in only Standard-quality wines. The correlation with sensory data indicated a strong relationship between volume, viscosity, and mannose content in Premium-quality wines, which was less pronounced in Standard-quality wines. Furthermore, parameters related to mouthfeel quality, such as roundness and smoothness, were also associated with these findings. Prospects involve further exploration of correlations between mouthfeel sensations, sensory descriptors, and the structural characteristics of mannoproteins, aiming for a more comprehensive understanding of the intricate interplay in wine composition.
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    Influence of grape quality tier, harvest timing, and yeast strain on mannoprotein content, phenolic composition, and color modulation in young red wines
    (Elsevier Ltd, 2025) Galaz Torres, Cristian; Vidal Zuñiga, Josefina Victoria; Vargas, Sebastián; Zincker, Jorge; Brossard, Natalia; Bordeu, Edmundo; Ricci, Arianna; Parpinello, Giuseppina P.; Versari, Andrea
    Besides the impact of harvest timing and grape quality, this study investigated the performance of selected yeast strains overproducing mannoproteins versus the conventional strain AGL 804 in terms of mannoprotein release and its consequences on the composition and color modulation of short-aged commercial red wines. The study fills a gap of volume and actual red wine production by comparing 36 winemaking conditions, each of 850 kg of grapes. The results showed that AGL 804 produced the same or more concentration of mannoproteins than the alternatives. Then, an apparent threshold was found for all yeasts when the dissolved solids content of grape musts at harvest exceeded 22 °Bx, beyond which no increase in mannoprotein production was observed. Only below this limit, an independent effect of yeast strains on tannin concentration and tannin-to-anthocyanin ratio (T/A) in wines was observed. These two parameters exhibited a moderate correlation with mannoprotein concentration (R2 = 0.534 and R2 = 0.696, respectively), and a low-moderate correlation for mannoprotein concentration with CIELAB color parameters. Wines produced from grapes > 22 °Bx showed only harvest-related variations in tannin concentration and T/A and no correlation between parameters analyzed and mannoprotein production. The study revealed that, although yeast strains influence the color of red wine after six months of bottling, their effect is secondary to the harvest timing. Moreover, the influence of the yeast strain itself was not consistent across the different harvest dates. Additionally, the study provides winemakers with an improved and practical assay for measuring mannoprotein levels in red wines, especially for small winery laboratories. It also introduces a novel 3D graphical representation of the CIELAB color parameters, which simultaneously integrates the real visible color of the wines and its visual discriminability to the human eye.