Enhancement of ester biosynthesis in blueberry wines through co-fermentation via cell-cell contact between Torulaspora delbrueckii and Saccharomyces cerevisiae.

This study investigated the effects of co-fermentation of T. delbrueckii and S. cerevisiae on the volatile composition and sensory characteristics of blueberry wines. Mixed fermentation led to higher levels of terpenes, higher alcohols, and esters compared to wines fermented with each yeast individually. Conversely, when T. delbrueckii were physically separated from S. cerevisiae in the double-compartment fermenter, contrasting outcomes emerged. The stronger fruity aroma induced by mixed fermentation were linked to higher ester concentrations, including isoamyl acetate, ethyl isovalerate, ethyl hexanoate, and diethyl succinate. The enhanced esters in mixed fermentation can be attributed to the upregulated alcohol acyltransferase activity and the expressions of ACC1, FAS2, ELO1 and ATF1 genes in late fermentation stage via the cell-cell contact between T. delbrueckii and S. cerevisiae. These findings can deepen the understanding of the interaction between non-Saccharomyces and S. cerevisiae in ester production, assisting wineries in effectively controlling wine aroma through mixed fermentations.

Enhancing blueberry wine aroma: Insights from cultivar selection and berry sorting.

This study aimed to improve the aroma quality of blueberry wine by employing cultivar selection and precise berry sorting. We conducted a comprehensive analysis of volatile profiles in blueberry wines derived from nine cultivars commonly cultivated in the middle region of China. 'Misty' and 'V3' blueberry wines exhibited pronounced floral aromas, closely linked to elevated terpenoid and phenylacetaldehyde content. 'Legacy' and 'Star' displayed a distinct fruity aroma profile attributed to the presence of ethyl 2-methylbutyrate, ethyl phenylacetate, and diethyl succinate. 'Jewel' featured an intense buttery aroma, correlated with higher concentrations of ethyl dodecanoate, ethyl decanoate, and ethyl octanoate. Subsequently, 'Misty' and 'Star', with distinct aroma profiles, were selected to further unravel the impact of berry size on blueberry wine aroma. The findings revealed that small berries significantly enhanced 'Misty' blueberry wines, increasing higher alcohol, ester, and terpenoid content, resulting in a more intense fruity and floral aroma. Interestingly, berry size had no discernible influence on 'Star' blueberry wine aroma. This study provides valuable insights into the enhancement of blueberry wine production, shedding light on the intricate interplay of cultivar selection, berry sorting, and their impact on the aromatic attributes of the final product.

Aroma enhancement of blueberry wine by postharvest partial dehydration of blueberries.

Blueberries with 20%, 30%, and 40% weight loss were used for winemaking, aiming to explore the feasibility of applying postharvest dehydration for improving blueberry wine aroma. Postharvest dehydration decreased the titratable acidity of blueberries and their resultant wines. Total anthocyanins and phenols in blueberries with 30% weight loss were increased by 25.9% and 16.1%, respectively, due to concentration effects, while further dehydration resulted in a decline. Similar trends were observed in blueberry wines. Moderate postharvest dehydration increased total terpenes, benzeneacetaldehyde and phenylethyl alcohol, ethyl butanoate, methyl salicylate, 1-hexanol, and γ-nonalactone content in blueberries and wines, which could enhance the floral, fruity, and sweet notes of blueberry wines. Wines made from blueberries under severe dehydration (40% weight loss) had the lowest overall aroma score, which was related to the higher content of 4-ethyl-phenol and 4-ethylguaiacol. In conclusion, moderate postharvest dehydration benefited the aroma enhancement of blueberry wine.