Exploring the ecological characteristics of natural microbial communities along the continuum from grape berries to winemaking

Insight into the effect of geography and variety on the wine flavory distinctness based on the variations of indigenous microbiota in Xinjiang of China

Wine fermentation and flavour formation are the result of complex biochemical reactions driven by the microbial activity at the influences of multiple scales, of which the regional distinctness is significantly affected by the specific microbiota. In the study, volatile profiles and fungal compositions were examined by analysis of HS-SPME-GC-MS and high-throughput amplicon sequencing. The results indicated that succinic acid levels were significantly altered by regional factor, while tartaric acid, lactic acid, and volatile acidity were significantly affected by varietal factor. A total of 71 volatiles was characterized and quantified in the resultant wines. Chemometric approaches (OPLS-DA and Random Forest clarification) were used to identify the key regional variations of volatiles from different varietal wines. Nine of the key volatiles were clarified in Cabernet Sauvignon wines, including 1-propanol, isoamylol, (E)-3-hexen-1-ol, 1-heptanol, phenylethyl alcohol, ethyl isovalerate, ethyl 2-methylbutanoate, diethyl succinate, and phenethyl acetate, while seven of the regional variations across Marselan wines were identified involving 1-octen-3-ol, 1-heptanol, ethyl acetate, isobutyl isovalerate, diethyl succinate, d-limonene, and nerol. The microbial amplicon-based result showed that the genera of Saccharomyces, Hanseniaspora, Aspergillus, and Cladosporium, were predominant on grape epidermis and during spontaneous fermentations, of which the relative abundances were adjusted by region, subregion, and variety. Correlation analysis highlighted that several non-fermentative fungi were significantly associated with aroma-active compounds with the exception of fermentative yeasts. This study underscores the intricate interplay between regional factors and varietal characteristics in shaping wine aroma characteristics, highlighting the importance of microbial diversity in enhancing wine quality and uniqueness.

Delaying quality deterioration with multifunctional gelatin-based film by inhibiting microbial growth in fresh-cut navel oranges

Maintaining the quality of fresh-cut navel oranges during storage remains a significant challenge due to microbial infestation. This study aimed to investigate the efficacy of a multifunctional gelatin-based (MG) film in retaining flavor, delaying quality deterioration, and extending the shelf life of fresh-cut navel oranges. Basic quality indicators demonstrated that MG film packaging effectively maintained the appearance and texture of fresh-cut navel oranges, reduced water loss and microbial growth, and extended the freshness period compared to unpacked samples and PE film. Additionally, the MG film packaging delayed a decline in the β-glucosidase (β-GC) activity, reduced fruit softening and flavor degradation, and maintained the volatile organic compounds (VOCs) content, particularly limonene and myrcene. The non-targeted metabolomics results showed that MG film significantly inhibited the degradation of organic acids, flavonoids, and sugars, further slowing the deterioration process. Furthermore, the MG film inhibited spoilage fungi (Penicillium, Aspergillus, and Pseudomonas) and foodborne bacteria such as Pantoea, Enterobacteriaceae, and Gluconobacter by restricting microbial nutrient utilization and metabolic activity, which modulated the microbial community structure and greatly delayed spoilage processes. This study highlighted the potential of MG film in delaying quality deterioration and extending the shelf life of fresh-cut fruits by inhibiting microbial growth.

Compositional Shifts in the Mycobiota of 'Shine Muscat' Grape (Vitis labruscana Baily × V. vinifera L.) Bunches During Cold Storage at Different Temperatures

The cultivation of 'Shine Muscat' grapes is rapidly expanding in East Asia due to their desirable qualities and muscat flavor. Studies have revealed that storing these grapes at an controlled freezing-point temperature diminishes their muscat flavor, whereas storage at 10 °C preserves it. However, the impact of a higher storage temperature on the evolution of microbial communities remains unclear. This study aimed to analyze the mycobiota dynamics of 'Shine Muscat' grape bunches under different cold storage temperatures. A total of 1,892,842 and 1,643,200 sequences were obtained from berries and pedicels, identifying over 208 fungal genera from 6 phyla. Xylariaceae was the most abundant family, with a prevalence between 7.21% and 69.27% across all sample groups. The primary genera included Zygosporium, Cladosporium, Aspergillus, Acremonium, Podosordaria, Zasmidium, Penicillium, and Alternaria. Spoilage-related fungi varied with storage temperature, with Aspergillus, Penicillium, and Alternaria being dominant at 0 °C and Cladosporium, Aspergillus, Penicillium, and Alternaria being prevalent at 10 °C. The fungal profiles of berries and pedicels differed significantly, and storage temperature further influenced these variations. Our findings highlight distinct fungal diversity and spoilage patterns in 'Shine Muscat' grape bunches from the Nanning region compared to those grown in temperate areas, revealing the unique microbial evolution of grape bunches stored at different temperatures in Nanning.

A Snapshot of Microbial Succession and Volatile Component Dynamics of Marselan Wine in Xinjiang During Spontaneous Fermentation

Marselan wine is characterized by distinctive flavors of blackcurrant, cranberry, and spice, which are significantly influenced by environmental factors such as region and climate. In this study, we analyzed the dynamic changes in the microbial community, physicochemical indices, and flavor compounds during the spontaneous fermentation of Marselan wine in Xinjiang using high-throughput sequencing (HTS), high-performance liquid chromatography (HPLC), and headspace solid-phase microextraction gas chromatography-mass spectrometry (HS-SPME-GC-MS). The results indicated that the sugar content decreased from 259.12 g/L to 22.45 g/L, while the ethanol content increased to 13.63 ± 0.15% vol after 12 days of fermentation. The predominant aromatic components identified in Marselan grapes include isophorone, 2,3-pentanedione, 2-hexenal, and melonal. After fermentation, ethanol, phenethyl alcohol, isoamyl acetate, ethyl acetate, and ethyl hexanoate were produced, imparting rose, cream, and fruit flavors to wine. The key microorganisms involved in the spontaneous fermentation of Marselan wine include Saccharomyces, Starmerella, Pichia, Pseudomonas, Sphingomonas, and Aspergillus. These microorganisms contributed substantially to the main physicochemical indices and flavor profiles. Saccharomyces and Pichia enhanced the formation of most alcohols and esters, whereas Aspergillus, Acremonium, and Fusarium inhibited the synthesis of numerous volatile compounds. These findings provide valuable theoretical references for improving the quality of Marselan wines in Xinjiang.

Dynamic Succession of Natural Microbes during the Ecolly Grape Growth under Extremely Simplified Eco-Cultivation

The composition and continuous succession of natural microbial communities during grape growth play important roles in grape health and flavor quality as well as in characterizing the regional wine terroir. This study explored the diversity and dynamics of fruit epidermal microbes at each growth and developmental stage of Ecolly grapes under an extremely simplified eco-cultivation model, analyzed microbial interactions and associations of weather parameters to specific communities, and emphasized metabolic functional characteristics of microecology. The results indicated that the natural microbial community changed significantly during the grape growth phase. The dominant fungal genera mainly included Gibberella, Alternaria, Filobasidium, Naganishia, Ascochyta, Apiotrichum, Comoclathris, and Aureobasidium, and the dominant bacterial genera mainly contained Sediminibacterium, Ralstonia, Pantoea, Bradyrhizobium, Brevundimonas, Mesorhizobium, Planococcus, and Planomicrobium. In summary, filamentous fungi gradually shifted to basidiomycetous yeasts along with fruit ripening, with a decline in the number of Gram-negative bacteria and a relative increase in Gram-positive bacteria. The community assembly process reflects the fact that microbial ecology may be influenced by a variety of factors, but the fungal community was more stable, and the bacterial community fluctuated more from year to year, which may reflect their response to weather conditions over the years. Overall, our study helps to comprehensively profile the ecological characteristics of the grape microbial system, highlights the natural ecological viticulture concept, and promotes the sustainable development of the grape and wine industry.

Diversity of 'Cabernet Sauvignon' Grape Epidermis and Environmental Bacteria in Wineries from Different Sub-Regions of the Eastern Foothills of Helan Mountain, Ningxia

Understanding the composition of the bacterial community on the epidermis of wine grapes and in winery environments, as well as the response of grape epidermal bacteria to climatic factors, plays a significant role in ensuring grape health and promoting grape conversion into wine. This study utilized high-throughput sequencing to explore the composition of the bacterial community on the wine grape epidermis and representative wineries of three sub-regions of the Eastern Foothills of Helan Mountain, Ningxia. The results showed that the bacterial diversity and richness in the Yongning (YN) sub-region were the highest, with Qingtongxia (QTX) having the lowest levels of grape epidermal bacteria. The bacterial diversity and richness were the highest in Yinchuan (YC) and the lowest in YN in the winery environment (p < 0.05). The composition of dominant bacteria on the grape epidermis and in winery environments of the three sub-regions was not different at the phylum and genus level, but the levels of these dominant bacteria were different among the sub-regions. There was a correlation between grape epidermal bacteria and climatic factors. Approximately 93% of the bacterial genera on the grape epidermal genera in the three sub-regions are present in the winery environment and contain all the dominant bacterial genera on the epidermis.

Vineyard-mediated factors are still operative in spontaneous and commercial fermentations shaping the vinification microbial community and affecting the antioxidant and anticancer properties of wines

The grapevine and vinification microbiota have a strong influence on the characteristics of the produced wine. Currently we have a good understanding of the role of vineyard-associated factors, like cultivar, vintage and terroir in shaping the grapevine microbiota. Notwithstanding, their endurance along the vinification process remains unknown. Thus, the main objective of our study was to determine how these factors influence (a) microbial succession during fermentation (i.e., bacterial and fungal) and (b) the antioxidant, antimutagenic and anticancer potential of the produced wines. These were evaluated under different vinification strategies (i.e., spontaneous V1, spontaneous with preservatives V2, commercial V3), employed at near full-scale level by local wineries, for two cultivars (Roditis and Sideritis), two terroir types, and two vintages. Cultivar and vintage were strong and persistent determinants of the vinification microbiota, unlike terroir whose effect became weaker from the vineyard, and early fermentation stages, where non-Saccharomyces yeasts, filamentous fungi (i.e., Aureobasidium, Cladosporium, Lachancea, Alternaria, Aspergillus, Torulaspora) and acetic acid bacteria (AAB) (Gluconobacter, Acetobacter, Komagataeibacter) dominated, to late fermentation stages where Saccharomyces and Oenococcus become prevalent. Besides vineyard-mediated factors, the vinification process employed was the strongest determinant of the fungal community compared to the bacterial community were effects varied per cultivar. Vintage and vinification type were the strongest determinants of the antioxidant, antimutagenic and anticancer potential of the produced wines. Further analysis identified significant positive correlations between members of the vinification microbiota like the yeasts Torulaspora debrueckii and Lachancea quebecensis with the anticancer and the antioxidant properties of wines in both cultivars. These findings could be exploited towards a microbiota-modulated vinification process to produce high-quality wines with desirable properties and enhanced regional identity.