Improving the aging aroma profiles of Italian Riesling and Petit Verdot Wines: Impact of spontaneous and inoculated fermentation processes.

The study employed gas chromatography-ion mobility spectrometry to differentiate between wines undergoing spontaneous fermentation and inoculated fermentation, with aging periods of 3, 9, and 15 months. The results indicate that throughout the three aging periods, there was a notable increase in the levels of ethyl hexanoate (Monomer, M), 2-methyl butanal, ethyl octanoate (M), ethyl octanoate (Dimer, D), propyl acetate, and 3-methylbutanal in the spontaneous Italian Riesling wine (RS). Furthermore, the compounds isoamyl acetate (M), ethyl formate (D), 4-methyl-2-pentanone (M), and ethyl formate (M) demonstrated the highest concentrations at 15 months in RS, accordingly, these compounds displayed a consistent upward trend throughout the aging period. A total of 14 volatile compounds exhibited an upward trend from 3 to 15 months in the spontaneous fermentation of Petit Verdot Wine (VS). Subsequently, these compounds attained their maximum levels. Spontaneous fermentation effectively enhances the aromatic characteristics of wines, consequently improving their capacity for aging.

Effects of Table Grape Cultivars on Fruit Quality and Aroma Components.

The basic physical and chemical qualities, nutrition, aroma components, and sensory evaluation of 17 varieties of table grapes were studied. The quality evaluation system of different table grape varieties was preliminarily determined. Our results show that the soluble solid content in Ruby Seedless was 21.17%, which was higher than that of other varieties. The black varieties Aishenmeigui and Sweet Sapphire had the highest total phenol content. Aishenmeigui had high levels of tannin and vitamin C. In addition, the aroma contents in Meixiangbao, Ruby Seedless, and Shine-Muscat were higher than those in other varieties. Manicure Finger and Ruby Seedless had higher levels of C6 compounds. Moreover, the "Kyoho" series of grape Meixiangbao, Sunmmer Black, Jumeigui, Hutai 8 hao, and Black Beet were high in ester content, while Muscat varieties, including Zaoheibao, Aishenmeigui, Jumeigui, and Shine-Muscat were rich in terpene substances. Ruby Seedless, Shine-Muscat, and Heibaladuo had higher comprehensive scores in sensory evaluation. Hence, the comprehensive quality of Shine-Muscat, Ruby Seedless, and Aishenmeigui was better. These results may serve as references for determining the quality differences between table grape varieties.

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

Under natural conditions, a complex and dynamic microbial ecosystem exists on the grape epidermis, which plays an important role in safeguarding grape health and facilitating the conversion of grapes into wine. However, current viticulture and vinification are flooded with excessive chemical additives and commercial ferments, leading to a reduction in microbial diversity, affecting the ecological balance of the natural microbiota and masking the wine terroir. This experiment comprehensively explored the continuous changes in the natural microbiota from the Ecolly (Vitis vinifera L.) grape epidermis to spontaneous fermentation over two years. The results suggested that microbial community structure and composition were significantly influenced by vintage and growing stage, with fungal genera being more stable than bacterial genera during the growing season. The fungal genera Alternaria, Ascochyta, Gibberella and Dissoconium and the bacterial genera Pantoea, Sediminibacterium, Ralstonia and Sphingomonas were mainly present on the grape epidermis in both years. The natural microbial diversity decreased from grape growth to spontaneous fermentation, and the fermentation environment reshapes the community structure, composition and diversity of the wine microbial consortium. These findings provide insights to promote cultivation and fermentation management strategies, advocate natural terroir attributes for grapes and wines, and promote sustainable development of the wine industry.

Natural and sustainable wine: a review.

With the awakening of consumers' awareness of sustainable development issues and demand for terroir wines, natural wines provide opportunities for the future development of the wine industry. Microbiomes are integral to viticulture and winemaking, where various microorganisms can exert positive and negative effects on grape health and wine quality. Communities of microorganisms associated with the vineyard play an important role in soil productivity as well as disease resistance developed by the vine. Wine is a fermented natural product, and the vineyard serves as a key point of entry for quality-modulating microbiota, particularly in wine fermentations that are conducted without the addition of exogenous yeasts. Thus, the sources and persistence of wine-relevant microbiota in vineyards critically impact its quality. In this review, we first examined that mimicking natural ecological cultivation to improve microbial diversity can enhance vineyard ecological services and reduce external inputs; then we examined that grape berries naturally possess all the elements of winemaking, including the nutrients for microbial growth, driving forces for the microbiota succession, and the enzymatic system for biochemical reactions; finally, we examined food safety, stability, specific interventions, and sustainability of natural wine industry-scale practices.

Diversity and Dynamics of Epidermal Microbes During Grape Development of Cabernet Sauvignon (Vitis vinifera L.) in the Ecological Viticulture Model in Wuhai, China.

Grapevine-related microorganisms affect the health and yield of grapes, the metabolic pathways of the fermentation process, and the regional characteristics of wine. However, the diversity of epidermal microorganisms during the development of berries under the ecological viticulture model has not been described in detail. In this study, high-throughput amplicon sequencing technology was used to perform ITS and 16S sequencing of Cabernet Sauvignon epidermal microbes at different developmental stages in the Wuhai region to investigate the succession of epidermal microbes and their response to developmental stages and vineyard weather. The results showed that the diversity of fungi and bacteria decreased during development. Epidermal microorganisms recruited members according to their developmental stages, but retained the core taxa, such as the fungi genera Alternaria, Jattaea, and Jattaea and the bacteria genera Brevundimonas, Sphingomonas, Acinetobacter, and Pseudomonas. In addition, the microbial diversity was associated with specific meteorological parameters, implying that there was a connection between the environmental conditions of the vineyard and the microbial distribution pattern such as the fungus genus Filobasidium was positively correlated with relative humidity and negatively correlated with average high temperature, average low temperature, and average ground temperature; the bacterium genus Lactobacillus was positively correlated with sunlight time, and negatively correlated with relative humidity. In conclusion, this study can help vineyard managers understand the microbial consortia associated with particular diseases, and also the dynamics of infection processes in order to take preventive actions, especially at the most critical moments.

Diversity and dynamics of microbial communities during spontaneous fermentation of Cabernet Sauvignon (Vitis vinifera L.) from different regions of China and their relationship with the volatile components in the wine.

Wine presents the most distinct geographic signatures among all agricultural products, and these geographic characteristics of the wine are enhanced by the actions of indigenous microorganisms. China is one of the largest wine-producing and consuming nations in the world. The wine-related microbial resources are abundant in China, although their geographic distribution patterns and their contribution to the aroma of wine remain to be elucidated. In the present study, Cabernet Sauvignon samples from four wine-producing regions in China were subjected to high-throughput sequencing and HS-SPME-GC-MS techniques to study the diversity and dynamics of the microorganisms that were present during the spontaneous fermentation process and to provide a preliminary understanding of the contribution of these microorganisms to the volatile components of the wine. The results revealed significant differences in the microbial diversity in the grape musts among different vineyards, which led to significant differences in the composition of the volatile metabolites of the produced wine. Moreover, while the fermentation process was observed to have reshaped the structure of the microbial community, specific characteristics of the vineyard were retained at the completion of the fermentation process. The associations between microbiota diversity and wine chemicals suggested that the dominant species during the fermentation process largely determined the volatile components of the wine. The present study enhances the understanding of Chinese wine terroir and provides a scientific basis for maintaining the regional microbial biodiversity to sustain viticulture and winemaking.

Community succession of the grape epidermis microbes of cabernet sauvignon (Vitis vinifera L.) from different regions in China during fruit development.

Grape surface microorganisms play a vital role in grape health and yield, wine quality, and regional wine characteristics. To investigate the succession of fungal and bacterial communities of the grape epidermis and the effects of development stages, vineyard location, and macroclimatic conditions on the diversity of epidermal microorganisms, 16S and ITS sequences of 36 samples from three different regions and four development stages were sequenced using the Illumina Novaseq platform. The Shannon index showed that the α-diversity of fungi and bacteria decreased during development. An analysis of variance showed that microbial diversity was influenced by development stage and vineyard location, and the development stage had a greater impact on the microbial diversity than the vineyard location. Grapes recruited microbes according to their developmental stages, but retain the core microbiome. Based on network analysis, this study found a significant correlation between epidermal microbial communities and macroclimatic conditions. In conclusion, the study described in detail the complex community dynamics of grape epidermal microorganisms during berry development. The result will help improve vineyard management techniques, rationally utilize the ecological functions of the vineyard, and reduce the application of chemical fungicides or pesticides to keep the vines healthy, produce high-quality grapes, and highlight the regional characteristics of the wine.

Diversity and dynamics of microbial ecosystem on berry surface during the ripening of Ecolly (Vitis vinifera L.) grape in Wuhai, China.

The structural and functional diversities of the microbial ecosystem on the grape surface affect the health of berries and the flavor of wines, which are also changed by many factors such as climate, weather conditions, agronomic practices, and physiological development. To understand and explore the natural characteristics of the grape surface microbial ecosystem during ripening, the species composition and dynamics of fungal and bacterial communities on the skin of Ecolly grape were determined by Illumina Novaseq platform sequencing. The results showed that 2146 fungal OTUs and 4175 bacterial OTUs were obtained, belonging to four fungal phyla and 20 bacterial phyla. The Shannon index indicated that the fungal community had the highest species diversity at the véraison stage and the bacterial community at the harvest stage. The four dominant fungal genera during grape ripening were Alternaria, Naganishia, Filobasidium, and Aureobasidium, which accounted for 82.8% of the total fungal community, and the dominant bacterial genera included Sphingomonas, Brevundimonas, Allorhizobium-Neorhizobium-Pararhizobium-Rhizobium, and Massilia, which accounted for 77.9% of the total bacterial community. The species richness and diversity in the grape microbial ecosystem changed constantly during the maturation stages, and there were strong correlations between certain core microbial genera, which may have an important impact on the function and ecological role of the community. This study provides a basis for understanding the natural characteristics of the microbial ecosystem on the grape surface during grape ripening, as well as the sustainable production concept of the microecology driving the viticulture management system.