Strategies on aroma formation in Chardonnay sparkling base wine: Different Saccharomyces cerevisiae strains, co-inoculation with Torulaspora delbrueckii and utilization of bentonite.

The worldwide production of sparkling wines has been growing annually, driven by a market demand for high quality and more complex products. The present study aimed to evaluate the fermentation of Chardonnay must using two different Saccharomyces cerevisiae yeasts, either alone (from commercial brands A and B) or in combination with Torulaspora delbrueckii (ScA + Td and ScB + Td, respectively), as well as the addition of bentonite to the fermentation with ScA (ScA + Ben), to investigate their impact on aroma formation in sparkling base wine. Enological parameters, volatile composition, and sensory profile were evaluated. The results showed notable differences in total sulfur dioxide and volatile acidity among the S. cerevisiae strains. Moreover, the esters ethyl acetate, isoamyl acetate, hexyl acetate, and phenethyl acetate showed significant differences among treatments. Esters are recognized for their contribution to fruity and floral aromas, making them an essential part of the aromatic profile of wines. The descriptive analysis revealed that ScB + Td had the highest intensity of floral and tropical fruit notes, as well as aromatic clarity. The use of bentonite did not affect the aromatic composition or sensory profile of the wine. Therefore, the co-inoculation of S. cerevisiae with T. delbrueckii can lead to a base wine with a higher intensity of important volatile compounds and sensory attributes, providing an important alternative to produce winery products with a more complex aroma profile.

Understanding the effect of fermentation time on physicochemical characteristics, sensory attributes, and volatile compounds in green tea kombucha.

Kombuchas are a trend in the fermented beverage field and the effect of fermentation time on their characteristics is necessary to better understand the process, mainly concerning volatile compounds, which are scarce information in the current literature. Thus, the present work aimed to evaluate the features of green tea kombucha during fermentation, monitoring the changes in pH, acidity, turbidity, polyphenols, ethanol, acetic acid, volatile compounds, and sensory profile and acceptance up to 14 days of fermentation. Kombuchas' pH and acidity decreased through time as expected, but after 4 days of fermentation, the beverage exceeded the Brazilian legal limits of acidity (130 mEq/L) and produced more than 0.5% AVB, which labels the beverage as alcoholic. Total polyphenols and condensed tannins content enhanced until the seventh day of fermentation and remained constant. Fermentation highly impacted the aroma of the infusion with a high formation of volatile acids, such as alcohols, esters, and ketones. Aldehydes were degraded during the bioprocess. Sensory characterization of kombucha showed that fermentation of 4 days increased perceived turbidity; vinegar, citric fruit, acid, and alcoholic aroma; and produced the beverage with sour, bitter, and vinegar flavor. Thus, the fermentation time of kombuchas must be controlled as they rapidly change and impact on the physicochemical parameters and sensory profile of the beverage can be negative.