This study examined the effects of honey varieties and non-Saccharomyces cerevisiae (Torulaspora delbrueckii and Kluyveromyces thermotolerans) on the flavor volatiles of mead. Five different types of mead were prepared from the honey varieties: vitex, acacia, linden, multifloral, and jujube. Among them, multifloral mead had the highest alcohol content, and acacia mead had the highest ester and acid content. As for the effect of non-Saccharomyces yeasts, vitex mead fermented with EC1118 exhibited the highest volatile-compound content, T. delbrueckii had the highest alcohol content (especially isopentanol and α-phenylethyl alcohol), and K. thermotolerans had the highest ethyl acetate and n-decanoic acid content. EC1118 had different effects on the flavor-volatile content of the two non-Saccharomyces cerevisiae fermented meads. Moreover, principal component analysis (PCA) and sensory analysis revealed considerable differences among the aroma components of the mead, which confirmed major differences among the aroma substances detected in this study.

Cherries are rich in bioactive phenolic compounds and are often fermented into cherry wines. The degradation of anthocyanins during storage will cause color deterioration. The study aimed to utilize sinapic acid and grape tannins in cherry wine to maintain a high fraction in the colored forms of anthocyanins, in order to maximize the color intensity, the latter being associated with good product quality. The effects on the anthocyanin profile and on color parameters of copigments, utilizing spectral measurement combined with UPLC-MS quantitative analysis, have been evaluated in sweet cherry wines. The copigmentation effect of sinapic acid and grape tannin was accompanied by the bathochromic shift and the hyperchromic effect, which lead to an increase in color intensity (lower L*, higher a* and b*). During the aging process, sinapic and grape tannin increased the content of pyranoanthocyanins in cherry wine, especially the addition of sinapic acid makes the cherry wine generate 10-syringyl-pyranocyanidin-3-rutinoside. These results demonstrate that sinapic acid is suitable for adding before alcohol fermentation, while grape tannins can be added before aging.

The effects of Metschnikowia pulcherrima and high glucose osmolality on S. cerevisiae pyruvate dehydrogenase pathway (PDH) by-pass were examined by varying the starting sugar concentration of synthetic grape juice and the inoculation ratio of S. cerevisiae to M. pulcherrima. The findings revealed that M. pulcherrima and osmolarity impacted S. cerevisiae’s PDH by-pass. The inoculation concentration of M. pulcherrima significantly affected pyruvate decarboxylase (PDC) activity and acs2 expression when the initial sugar concentration was 200 g L⁻¹ and 290 g L⁻¹. The osmolarity caused by the initial sugar (380 g L⁻¹) significantly influenced the enzymatic activity of S. cerevisiae, which decreased PDC and acetaldehyde dehydrogenase (ALD) activities while increasing Acetyl-CoA synthetase (ACS) activity. The reduction in acetic acid in the wine was caused by M. pulcherrima altering the initial sugar concentration faced by S. cerevisiae, which in turn affected enzymatic activity. The alteration of enzyme activity and accumulation of primary metabolites revealed why mixed fermentation could reduce the acetic acid content in wine by altering the enzymatic activity and affecting the expression of several key genes. The M. pulcherrima inoculation levels had no significant effect on the acetic acid and glycerol concentration in the same fermentation medium.

Several studies have revealed that fruit-zone leaf removal could change the microclimate of grapevine growth, thereby causing complex effects on fruit composition. This study analyzed the profiles of volatiles in Cabernet Sauvignon (Vitis vinifera L.) grapes exposed to leaf removal treatment at different phenological periods in three continuous years. The treatments (leaf removal before flowering, after flowering, and veraison) were applied to Cabernet Sauvignon grapevines grown in Yantai (Shandong, China). Berry samples were harvested at maturation to determine the chemical composition, including total soluble solids, phenols, and volatiles. Leaf removal (particularly before flowering) could increase total soluble solids and phenols (anthocyanins, flavonols, and tartaric esters). Volatiles greatly changed in the different years, and leaf removal before flowering could increase the concentration of amino acid-derived volatiles and isoprene-derived volatiles compared with leaf removal after flowering or at veraison. This research provides a basis for further studies on optimizing Cabernet Sauvignon aroma and breeding in vineyards.

Grapevine (Vitis vinifera) is one of the major economic fruit crops but suffers many diseases, causing damage to the quality of grapes. Strain G166 was isolated from the rhizosphere of grapevine and was found to exhibited broad-spectrum antagonistic activities against fungal pathogens on grapes in vitro, such as Coniella diplodiella, Botrytis cinerea, and Colletotrichum gloeosporioides. Whole-genome sequencing revealed that G166 contained a 6,613,582 bp circular chromosome with 5749 predicted coding DNA sequences and an average GC content of 60.57%. TYGS analysis revealed that G166 belongs to Pseudomonas viciae. Phenotype analysis indicated that P. viciae G166 remarkably reduced the severity of grape white rot disease in the grapevine. After inoculation with C. diplodiella, more H₂O₂ and MDA accumulated in the leaves and resulted in decreases in the Pn and chlorophyll content. Conversely, G166-treated grapevine displayed less oxidative damage with lower H₂O₂ levels and MDA contents under the pathogen treatments. Subsequently, G166-treated grapevine could sustain a normal Pn and chlorophyll content. Moreover, the application of P. viciae G166 inhibited the growth of mycelia on detached leaves and berries, while more disease symptoms occurred in non-bacterized leaves and berries. Therefore, P. viciae G166 served as a powerful bioagent against grape white rot disease. Using antiSMASH prediction and genome comparisons, a relationship between non-ribosomal peptide synthase clusters and antifungal activity was found in the genome of P. viciae G166. Taken together, P. viciae G166 shows promising antifungal potential to improve fruit quality and yield in ecological agriculture.