The purpose of this study was to explore the application potential of Meyerozyma guilliermondii NM218 in dry red wine pilot production. Cabernet Sauvignon wines were made by sequential inoculation of NM218 and commercial Saccharomyces cerevisiae (FX10) at an interval of 48 h (treatment group) or single inoculation of FX10 (control group). The alcoholic fermentation process and yeast growth status were monitored, and the physicochemical indicators, color and aroma components of wine were measured at the end of alcoholic fermentation and after five months of aging. Moreover, sensory evaluation was carried out to the effect of mixed culture fermentation on the quality of ‘Cabernet Sauvignon’ dry red wine. The results showed that the viable count of M. guilliermondii remained higher than 10⁵ CFU/mL before the middle stage of alcoholic fermentation, and completely disappeared at the end of fermentation. The process of alcoholic fermentation in the treatment group was prolonged by 2 to 3 days compared with that in the control group. The basic physicochemical indicators of the wine samples met the requirements of the national standard GB/T 15037-2006 Wines. Compared with the control group, the total anthocyanin content and the percentage of individual anthocyanins in the treatment group at the end of alcoholic fermentation and after five months of aging were significantly decreased (P < 0.05), and the CIELab color parameters and ionization index were significantly increased (P < 0.05). At the end of alcoholic fermentation, the contents of aroma substances such as ethyl butyrate (97%), isoamyl acetate (123%), ethyl caproate (59%), methyl caprylate (43%), phenylethyl acetate (61%), and citronellol (55%) in the treatment group increased compared with the control group. After five months of aging, the contents of aroma substances such as ethyl heptanoate (151%), diethyl succinate (63%) and ethyl myristate (83%) increased compared with the control group. Two aroma compounds were exclusively found in the treatment group, which could impart a rich fruity aroma to the wine. Sensory evaluation showed that the mixed culture fermented wine had a purple-red color, harmonious body, and rich aroma and scored high overall after five months of aging. In conclusion, sequential inoculation of NM218 and FX10 can enhance the aroma quality and sensory pleasure of dry red wine, and has the potential for industrial application.

In order to explore the effects of biodynamic vineyard management on the yeast community structure and volatile aroma components during wine fermentation, Cabernet Sauvignon grapes from biodynamic (BD) and conventional (CV) vineyards were naturally fermented, and the composition and succession of yeast community and aroma components were analyzed during the fermentation process, and the correlation between yeast communities and aroma components was analyzed by redundant analysis (RDA). The results showed significant differences in the yeast community composition between the BD and CV samples at different fermentation stages. At the early stage, Hanseniaspora uvarum, Starmerella bacillaris, Pichia kudriavzevii, Issatchen kiaorientalis and Cryptococus flavescens were the dominant species in BD, while H. uvarum, Metschnikowia pulcherrima and C. flavescens were the dominant species in CV. As the fermentation proceeded, the yeast species in BD and CV increased to 9 and 7 at the middle stage, respectively. H. uvarum was the dominant yeast in both samples. The non-Saccharomyces species decreased at the later and final stages of fermentation, Saccharomyces cerevisiae gradually became the dominant species, but Hanseniaspora opuntiae and S. bacillaris were found in CV but not BD at the end of fermentation. During the alcoholic fermentation process, the total content of aroma compounds was significantly higher in BD than in CV. Meanwhile, at all stages of fermentation, the contents of alcohols, aldehydes, and terpenes were higher in BD than in CV. However, the content of esters was lower in BD than in CV. RDA analysis showed that S. cerevisiae was positively correlated with the contents of all characteristic aroma components except benzaldehyde, and non-Saccharomyces yeasts (H. opuntiae, P. kudriavzevii, etc.) were positively correlated with the contents of 1-hexanol, benzaldehyde and ethyl acetate. In summary, this study provides data support for understanding the influence of different vineyard managements on the microbial diversity of vineyard and the aroma quality of grape and wine.

This study aimed to investigate the correlation between microbial community succession and volatile compounds during the spontaneous fermentation of Pinot Noir wine at an industrial scale. Pinot Noir grapes from the production region of Wuwei in the Hexi Corridor were used to produce wine by spontaneous fermentation. High-throughput sequencing was used to monitor the succession of the indigenous microbial community during the fermentation process, and volatile compounds were qualitatively and quantitatively analyzed by headspace solid-phase microextraction (HS-SPME) coupled with gas chromatography-mass spectrometry (GC-MS). Besides, the correlation between core indigenous microorganisms and volatile compounds was investigated using Spearman correlation coefficients. The results showed that the dominant microorganisms were Mycosphaerella, Pichia, Saccharomyces and Tatumella during the fermentation process, Mycosphaerella and Pichia being the dominant fungal genera during the early fermentation period with relative abundances of 44.67% and 18.28%, respectively, whereas the relative abundance of Saccharomyces increased gradually up to 48.42%, which became the dominant fungal genus at the end of the fermentation period. Tatumella was the most dominant bacterial genus during the late fermentation period, as its relative abundance increased gradually up to 44.66% and then remained basically unchanged. In addition, the dominant genera Komagataeibacter, Pantoea and Saccharomyces were positively correlated with the key volatile aroma substances including ethyl butyrate, ethyl caproate and phenylethanol, whose final concentrations were 164.04, 4585.75 and 3694.11 µg/L, respectively, at the end of the fermentation period, imparting floral, fruity and honey-like aromas to the wine. However, the dominant bacterial genera Sphingomonas, Methylobacterium and Mycosphaerella, Aspergillus were negatively correlated with most of the key aroma substances. The results of the present study provide a theoretical basis for improving the quality of wine in the Hexi Corridor.