Wine Fermentation Research Articles

Correlation between changes in flavor compounds and microbial community ecological succession in the liquid fermentation of rice wine.

Microorganisms play an important role in regulating flavor compounds in rice wine, whereas we often don't understand how did they affect flavor compounds. Here, the relations between flavor compounds and microbial community ecological succession were investigated by monitoring flavor compounds and microbial community throughout the fermentation stage of rice wine. The composition of microbial community showed a dynamic change, but 13 dominant bacterial genera and 4 dominant fungal genera were detected throughout the fermentation stages. Saccharomyces presented a strong negative correlation with fungi genera but had positive associations with bacteria genera. Similarly, flavor compounds in rice wine were also showed the dynamic change, and 112 volatile compounds and 17 free amino acids were identified in the whole stages. The alcohol-ester ratio was decreased in the LTF stage, indicating that low temperature boosts ester formation. The potential correlation between flavor compounds and microbial community indicated that Delftia, Chryseobacterium, Rhizopus and Wickerhamomyces were the core functional microorganisms in rice wine. These findings clarified the correlation between changes in flavor compounds and in microbial community in the liquid fermentation of rice wine, and these results have some reference value for the quality improvement and technological optimization in liquid fermentation of rice wine.

Enhancement of pyranoanthocyanin formation in blueberry wine with non-Saccharomyces yeasts

The development of blueberry wine provides an alternative method for maintaining the nutritional value and extending the shelf life of blueberries. However, anthocyanin loss and off-flavor compound generation during fermentation impair blueberry wine color and quality. Hydroxycinnamate decarboxylase from yeast can catalyze the conversion of hydroxycinnamic acids to vinylphenols, which later may condense with anthocyanins to form more stable vinylphenolic pyranoanthocyanins. In this study, 10 non-Saccharomyces yeasts from Daqu that showed hydroxycinnamate decarboxylase activity were screened. Among the 10 strains, Wickerhamomyces anomalus Y5 showed the highest consumption (34.59%) of the total tested phenolic acids and almost no H2S production. Furthermore, Y5 seemed to produce four vinylphenol pyranoanthocyanins (cyanidin-3-O-galactoside/glucoside-4-vinylcatechol, cyanidin-3-O-galactoside/glucoside-4-vinylsyringol, malvidin-4-vinylguaiacol, and malvidin-4-vinylcatechol) during blueberry wine fermentation, which may improve the color stability of blueberry wine. These findings provide new insights for improving the quality of blueberry wine using non-Saccharomyces yeasts.

Exploring the stress mechanism of tannic acid on Saccharomyces cerevisiae based on transcriptomics

Tannic acid is a polyphenolic substance widely in fruits, but the effect of tannic acid in fruit wine fermentation on Saccharomyces cerevisiae is still unknown. This study used tannic acid (1.6 g/L) to treat S. cerevisiae, the mechanism of the influence of tannic acid on the S. cerevisiae was further explored through transcriptomics technology. The results showed that the growth, ethanol yield and volatile substances of S. cerevisiae under tannic acid stress decreased by 71.76%, 46.49% and 85.58%, respectively. The activities of PDC and ADH of ethanol metabolism pathway decreased by 9.26% and 57.82%, respectively. Transcriptomic analysis showed that a total of 2890 differentially expressed genes were identified, of which 1499 genes were upregulated and 1391 genes were downregulated. Genes associated with the cell cycle, meiosis, and TCA cycle pathways were significantly induced, so S. cerevisiae responded to tannic acid stress through sexual reproduction and energy metabolism. The downregulation of genes related to cell wall integrity indicated that tannic acid destroyed the structure of the cell wall and inhibited its growth. In addition, downregulation of genes encoding glycolysis and pentose phosphate pathways were observed, resulting in significant inhibition of the ethanol metabolism pathway of S. cerevisiae. This study initially revealed the stress mechanism of tannic acid on S. cerevisiae and provided a basis for further studies to improve the tolerance in S. cerevisiae.

Correlation of microbial community structure and volatile flavor compounds during corn yellow wine fermentation.

High-throughput sequencing was used to define microbial community structure and GC-MS to identify volatile flavor substances during fermentation of corn yellow wine, and results were analyzed by multivariate statistical analysis. Seventeen bacterial phyla, 239 bacterial genera, 4 fungal phyla, and 18 fungal genera were found and changes in community structure occurred during fermentation. Twenty-four volatile flavor substances, including 14 esters and 5 alcohols, were detected and changes during fermentation recorded. Sixteen microbial genera correlated with volatile flavor substances and Weissella, Lactobacillus, Pseudomonas, Rhodotorul, and Kwoniella had significant correlation with ethyl esters and higher alcohols. Micro-organisms thus influence flavor development during corn yellow wine fermentation.

Removal of ochratoxin A in wine by Cryptococcus albidus and safety assessment of degradation products.

Ochratoxin A (OTA) is a mycotoxin that contaminates grape-based products and is extremely harmful to the health of the host. It is effectively removed by yeast during the fermentation of wine, whereas the removal mechanism of OTA remains unclear. Therefore, the present study aimed to investigate the removal mechanism of ochratoxin A by yeast and to evaluate the safety of its degradation products. Cryptococcus albidus (20-G) with better effect on ochratoxin A (OTA) was screened out in the main fermentation stage of wine. The results showed that 20-G removed OTA through biosorption and biodegradation. Intracellular enzymes played the main role (18.44%) and yeast cell walls adsorbed a small amount of OTA (8.44%). Furthermore, the identification of proteins in 20-G revealed that the decrease in OTA content was mainly a result of the action of peroxidase, and validation tests were carried out. By analyzing the degradation products of OTA, OTα and phenylalanine with lower toxicity were obtained. Animal experiments showed that the intervention of yeast 20-G reduced the damage and adverse effects caused by OTA toxicity to the mice. The present study demonstrates the mechanism of OTA removal by 20-G and the toxicity of OTA was reduced by peroxidase in 20-G. © 2023 Society of Chemical Industry.

PKA-Msn2/4-Shy1 cascade controls inhibition of proline utilization under wine fermentation models

Proline, which is a predominant amino acid in grape musts, is involved in the taste and flavor of foods and beverages. The yeast Saccharomyces cerevisiae poorly utilizes proline in wine-making processes, leading to a nitrogen deficiency during fermentation and proline accumulation in wine. Previous studies have shown that the protein kinase A (PKA) pathway is involved in inhibitory mechanisms of proline utilization. In this study, we screened the PKA pathway-related genes that regulate proline utilization. Using a yeast culture collection of disrupted strains associated with the downstream of the PKA cascade, we revealed that the stress-responsive transcription factor genes MSN2/4 regulate proline utilization. Moreover, we found that Msn2/4 up-regulate the SHY1 gene during the cell growth of the wine fermentation model, which may cause the inhibition of proline utilization. The SHY1-deleted strain of the commercial wine yeast clearly showed proline consumption and average ethanol production under the wine fermentation model. The present data indicate that the PKA-Msn2/4-Shy1 cascade controls the inhibition of proline utilization under wine-making processes. Our study could hold promise for the development of wine yeast strains that can efficiently reduce proline during wine fermentation.

Fermented traditional wine from palm trees: microbial, nutritional attributes and health impacts

Fermented wine from palm trees is gaining more acceptance by consumers given its natural and health promoting attributes. The traditional wine is fermented from the extracted sap of palm trees by microbes, however, excessive contamination by spoilage microorganisms must be avoided, storage conditions must be ensured to foster its natural fermentation. The importance and quality of this locally produced fermented wine will benefit from a better understanding of the scientific knowledge on its micro and macro nutrients. In this review paper, we explore the science of the traditional fermentation process that leads to the sweet, effervescent, milky but alcoholic beverage known as palm wine or toddy. The microbes that are involved in its fermentation (especially yeasts and lactic acid bacteria) are of interest towards realising the potential economic benefits that will be gained from the standard production of palm wine. It is important to emphasize ‘sustainability’ in the entire value chain of palm wine as an industry starting from its cultivation, to its processing, side streams, storage and consumption. In addition, the packaging materials for the large-scale production of palm wine will need to be eco-friendly when sustainability is considered.

Influence of an indigenous yeast, CECA, from the Ningxia wine region of China, on the yeast community dynamics and aroma of Cabernet Sauvignon wines

Commercial yeasts are normally used in the wine industry to achieve stable and enhanced wine flavors and aromas, but they can lead to a loss of diversity and a peculiar regional wine style. An indigenous commercial wine yeast, CECA, has been isolated from a well-known wine-producing region, Ningxia, China. As CECA is a young commercial yeast, further research into its characteristics is required. In this study, the performance of CECA in Cabernet Sauvignon wine fermentation, three different fermentation treatments, spontaneous without inoculation, inoculated with CECA, and inoculated with CECA after treatment of the grape must with dimethyl dicarbonate, were performed. During fermentation, six species of yeast identified through a culture-dependent method were also identified with a culture-independent method, although the relative abundance differed between the methods. The floral and fruity were confirmed as characteristics of CECA-inoculated wines using headspace solid-phase microextraction-gas chromatography-mass spectrometry and sensory evaluation. This study enables winemakers to better understand an indigenous commercial yeast, make a peculiar aroma for Ningxia wines and promote the reputation of Ningxia region.

Investigation of wine fermentation of three-leaf cayratia (Cayratia trifolia L.) using Saccharomyces cerevisiae 2.1

Background: Cayratia trifolia has been extensively studied for its bioactive components and medicinal properties. This study was carried out to evaluate the fermentation ability of Saccharomyces cerevisiae 2.1 yeast to determine suitable fermentation conditions. Methods: The initial sugar content for three-leaf cayratia fermentation and fermentation efficiency were calculated. The temperature for three-leaf cayratia fermentation, incubation time, and preliminary 1 liter of three-leaf cayratia wine fermentation were determined. All treatments showed that the total sugar content decreased after 9 days of fermentation compared to the initial level. Temperature during fermentation has a direct effect on yeast activity. Temperature increases the growth of yeast and speed of enzyme activity. The fermentation time changes depending on temperature, initial soluble solid contents, and yeast strains, leading to changes in the ethanol content after the end of fermentation. Results:The results showed that the S. cerevisiae 2.1 strain was able to ferment at room temperature with an initial pH of 4.5, 24 °Brix, and a yeast density of 107 cells/mL. The appropriate fermentation conditions determined for S. cerevisiae 2.1 yeast were 24 °Brix and incubation at room temperature (28-33°C) with a fermentation time of 11 days. Concusion: In 1 liter scale fermentation, three-leaf cayratia wine had 9.46% (v/v) and the fermentation efficiency was 90.34%. The wine produced had a unique color, flavor, and aroma that met the sensory evaluation of the Vietnamese standard TCVN-3217:79.

Physicochemical attributes and acceptability of marula wine fermented with natural Lactiplantibacillus plantarum and Saccharomyces cerevisiae

The aim of the study was to test the acceptability and physico-chemical characteristics of marula wine fermented with known cultures of natural Lactiplantibacillus plantarum and Saccharomyces cerevisiae. The LAB Lactobacillus and Saccharomyces dominate the fermentation of marula wine throughout the fermentation period. These were isolated and identified from the spontaneously fermented marula wine and re-inoculated as single cultures and as mixed cultures to ferment marula juice into wine. The Saccharomyces cerevisiae combined with Lactiplantibacillus plantarum (PYL) and Saccharomyces cerevisiae (PY) fermented wines were not significantly different (p ≥ 0.05) in all the physico-chemical characteristics and acceptability. The single culture of Lactiplantibacillus plantarum had the lowest pH of 2.8. The alcohol content of marula wine fermented with Saccharomyces cerevisiae was 6.10 ± 0.17, while the alcohol content of the spontaneously fermented wine was 3.33 ± 2.49. The oBrix of wine fermented with Saccharomyces cerevisiae only and as mixed culture was 2.07 ± 0.21 and 2.00 ± 0.00, respectively, while the control and Lactiplantibacillus plantarum had an oBrix of 6.23 ± 2.77 and 8.67 ± 0.06, respectively. The Lactiplantibacillus plantarum fermented sample and the control had significantly higher overall acceptability scores of 7.60 and 6.98, respectively. Saccharomyces cerevisiae is capable of producing ethanol as a single culture and co-cultured with Lactobacillus plantarum. The most preferred wine was that fermented by Lactiplantibacillus plantarum only because of its sweetness.

Correlation between fungi and volatile compounds during different fermentation modes at the industrial scale of Merlot wines

Elucidation of the relationship between fungal community development and dynamic changes in volatile components during fermentation is of great significance in controlling wine production. However, such studies on an industrial scale are rarely reported. In this study, fungal community succession during spontaneous fermentation (SPF) and inoculation fermentation (INF) of Merlot wine was monitored by a research strategy combining culture-dependent and culture-independent methods. The volatile compounds were monitored during SPF and INF by headspace solid-phase micro-extraction coupled with gas chromatography-mass spectrometry technology. The Spearman correlation coefficient was also used to investigate the interplay between fungal communities and volatile compounds. We found that fungal community diversity in SPF decreased as fermentation progressed but was significantly higher than that of INF. Starmerella and Kazachstania were the dominant non-Saccharomyces genera in Merlot wine during SPF. However, the presence of commercial yeasts and sulphur dioxide led to a sharp decrease or the disappearance of non-Saccharomyces genera during INF. Spearman correlation analysis revealed that all major volatiles were positively correlated with most functional microbiotas except P. fermentans, S. bacillaris, E. necator, and D. exigua in INF. In SPF, most non-Saccharomyces were negatively correlated with core volatiles, whereas K. humilis, M. laxa, P. kluyveri, and A. japonicus were positively correlated with the major volatiles, especially some higher alcohols (isopentol, heptanol) and terpenes (linalool, citronellol). S. cerevisiae was positively correlated with most of the main volatile substances except ethyl isovalerate and isoamyl acetate. These findings provide a reference for comprehending the diverse fermentation methods employed in the wine industry and improving the quality of Merlot wines.

Study on the Dynamics of Microflora during Natural Fermentation of Different Blueberry Wines

Microflora play an important role in the fermentation of blueberry wine, influencing the flavor and nutrient formation. Commercial yeasts give blueberry wines an average flavor profile that does not highlight the specific aroma and origin of the blueberry. In the present study, ITS1-ITS2 region sequencing analysis was performed using Illumina MiSeq high-throughput technology to sequence fermented blueberry wine samples of three Vaccinium ashei varieties, Gardenblue, Powderblue, and Britewell, from the Majiang appellation in Guizhou province to analyze the trends of fungal communities and the diversity of compositional structures in different periods of blueberry wine fermentation. The study’s results revealed that 114 genera from seven phyla were detected in nine samples from different fermentation periods of blueberry wine. The main fungal phyla were Ascomycota, Basidiomycota, Kickxellomycota, Chytridiomycota, and Olpidiomycota. The main fungal genera were Hanseniaspora, Saccharomyces, unidentified, Aureobasidium, Penicillium, Mortierella, Colletotrichum, etc. Hanseniaspora was dominant in the pre-fermentation stage of blueberry wine, accounting for more than 82%; Saccharomyces was the dominant genera in the middle and late fermentation stages of blueberry wine, with Saccharomyces accounting for more than 72% in the middle of fermentation and 93% in the late fermentation stage. This study screened indigenous flora for the natural fermentation of blueberry wine in the Majiang production area of Guizhou, improved the flavor substances of the blueberry wine, highlighted the characteristics of the production area, and made the blueberry wine have the characteristic flavor of the production area.

Endo metabolomic profiling of flor and wine yeasts reveals a positive correlation between intracellular metabolite load and the specific glycolytic flux during wine fermentation.

This study explored the intracellular metabolic variations between 17 strains of Saccharomyces cerevisiae belonging to two different genetic populations: flor and wine yeasts, in the context of alcoholic fermentation. These two populations are closely related as they share the same ecological niche but display distinct genetic characteristics. A protocol was developed for intracellular metabolites extraction and 1H-NMR analysis. This methodology allowed us to identify and quantify 21 intracellular metabolites at two different fermentation steps: the exponential and stationary phases. This work provided evidence of significant differences in the abundance of intracellular metabolites, which are strain- and time-dependent, thus revealing complex interactions. Moreover, the differences in abundance appeared to be correlated with life-history traits such as average cell size and specific glycolytic flux, which revealed unsuspected phenotypic correlations between metabolite load and fermentation activity.

Box–Behnken design to determine optimal fermentation conditions for apple-fortified mulberry wine using Saccharomyces bayanus

Wine is a fermented product of fruit juice. Mulberry and apple juice can also be used to produce wine. Several factors influence the alcoholic fermentation of the must; therefore, the optimization of the mulberry wine fermentation conditions with the dry yeast strain Saccharomyces bayanus (concentration varied from 0.15 to 0.25 g/L), fermentation conditions as pH value (from 3.5 to 4.5), and total soluble solid (TSS) content (24–28°Brix) were performed in this study. To evaluate the influence of these factors, a Box–Behnken design was used to minimize the number of factor combinations required, which allows the determination of optimal fermentation conditions (pH, TSS content, and dry yeast concentration) to produce wines with high alcohol and bioactive compounds (total anthocyanin (TAC) and polyphenol content (TPC)). Based on the analysis of experimental data, the second-order response surface models were developed to describe the relationship between initial pH value, TSS, and dry yeast concentration on wine quality acquisition (ethanol content and bioactive compounds). The results of the analysis of variance (ANOVA) showed that the model setup by response surface quadratic regression was suitable for predicting the wine quality. It was observed that the quality of the apple-fortified mulberry wine was significantly affected by all variables. The optimal contents of ethanol, total anthocyanin, and total polyphenol were achieved at 12.97% (v/v), 171.85 mg/L, and 87.17 mgGAE/L, respectively, when fermented in juice medium with optimal values of pH, TSS, and yeast concentration of 3.9, 26°Brix, and 0.22 g/L, respectively.

Integrated genomics and phenotype microarray analysis of Saccharomyces cerevisiae industrial strains for rice wine fermentation and recombinant protein production.

The industrial potential of Saccharomyces cerevisiae has extended beyond its traditional use in fermentation to various applications, including recombinant protein production. Herein, comparative genomics was performed with three industrial S. cerevisiae strains and revealed a heterozygous diploid genome for the 98-5 and KSD-YC strains (exploited for rice wine fermentation) and a haploid genome for strain Y2805 (used for recombinant protein production). Phylogenomic analysis indicated that Y2805 was closely associated with the reference strain S288C, whereas KSD-YC and 98-5 were grouped with Asian and European wine strains, respectively. Particularly, a single nucleotide polymorphism (SNP) in FDC1, involved in the biosynthesis of 4-vinylguaiacol (4-VG, a phenolic compound with a clove-like aroma), was found in KSD-YC, consistent with its lack of 4-VG production. Phenotype microarray (PM) analysis showed that KSD-YC and 98-5 displayed broader substrate utilization than S288C and Y2805. The SNPs detected by genome comparison were mapped to the genes responsible for the observed phenotypic differences. In addition, detailed information on the structural organization of Y2805 selection markers was validated by Sanger sequencing. Integrated genomics and PM analysis elucidated the evolutionary history and genetic diversity of industrial S. cerevisiae strains, providing a platform to improve fermentation processes and genetic manipulation.

Adjusting the pomace ratio during red wine fermentation: Effects of adding white grape pomace and juice runoff on wine flavoromics and sensory qualities

Adding pomace or juice runoff during maceration is a traditional winemaking process. To mitigate the negative effects of rainfall during harvest and examine the effects of adjusting the pomace ratio during fermentation on the flavor profile of Marselan grape wines, the prefermentation addition of Petit Manseng grape pomace (PAP) and prefermentation juice runoff (PJR) was determined. The phenolic and volatile compounds were investigated using HPLC–MS and GC–MS. PAP enriched the flavanols and PJR enriched the pigment and copigment matrix. Approximate 10% increase in the ratio of pomace promoted the formation of anthocyanin derivatives. The increased pomace ratio reduced the concentration of volatile compounds without impacting the aroma quality. Sensory analysis revealed PAP wines scored higher for acidity and astringency and PJR wines scored higher for color. In conclusion, an appropriate increase in the pomace ratio of approximately 10% can enhance the color and mouthfeel of the wine while having a limited influence on aroma.

Leaching and evolution of anthocyanins and aroma compounds during Cabernet Sauvignon wine fermentation with whole-process skin-seed contact

This study explores the leaching and evolution of anthocyanins and aroma compounds during wine-making, using an industrial-scale vinification of Cabernet Sauvignon with whole-process skin-seed contact. The results indicated that compounds within the same class displayed similar evolutionary patterns during fermentation. The extraction of anthocyanins, C6 aldehydes, and β-damascenes occurred continuously during cold soak, accompanied by the conversion of C6 aldehydes into alcohols and hydrolytic release of glycosidic β-damascenone. During alcoholic fermentation, pyranoanthocyanins, polymeric pigments, esters, benzene compounds, higher alcohols, and acids were generated. The concurrent occurrence of malolactic fermentation and prolonged maceration led to aromas associated with lactic acid bacteria metabolism. Finally, a comparison between free-run wine and pressed wine revealed high concentrations of C6 compounds and polymeric pigments with flavanol dimers in the pressed wine. These results can be used as a reference to optimize the vinification process to enhance the red due and fruity aromas of the wine.

Wine aroma modification by Hanseniaspora uvarum: A multiple-step strategy for screening potential mixed starters

Hanseniaspora uvarum is a prevalent yeast species in vineyards. However, its application in grape wine fermentation remains limited. This study used culture-dependent and -independent approaches to investigate the dynamics of H. uvarum during the spontaneous fermentation of Cabernet Sauvignon grapes. The results revealed that H. uvarum constituted 77.49 % of the non-Saccharomyces yeast population during fermentation. An indigenous strain, QTX-C10, was isolated from the 148 H. uvarum strains using a multistep screening strategy. The 1:1 co-inoculation of QTX-C10 with Saccharomyces cerevisiae proved to be an optimal strategy for mixed fermentation, resulting in a 48.54 %–59.55 % increase in ethyl esters in Cabernet Sauvignon wine and a 96.94 %–110.92 % increase in Chardonnay wine. Furthermore, this approach reduced the acetic acid levels by 12.50 %–17.07 % for Cabernet Sauvignon wine and 10.81 %–17.78 % for Chardonnay wine. Additionally, increased ethyl ester content may enhance the tropical fruit flavor of Cabernet Sauvignon wines.

Identification of dominant functional microbes that contribute to the characteristic aroma of Msalais, traditional wine fermented from boiled local grape juice in China.

Msalais is a traditional wine produced from naturally fermented boiled local grape juice in China. It has characteristic dried fruit and caramel odors, mainly attributed to aromatic compounds, such as furaneol and 5-methylfurfural. However, it is unclear how microbes involved in the natural fermentation of Msalais contribute to this characteristic aroma. Here, we analyzed the Msalais-fermenting microbes and aromatic compounds formed during natural Msalais fermentation by using high-throughput sequencing and gas chromatography-mass spectrometry, respectively. The analysis revealed that Saccharomyces cerevisiae, Kazachstania humilis, Lactobacillus plantarum, and Lactobacillus farraginis are the dominant and key functional species that produce high amounts of furaneol and 5-methylfurfural during Msalais fermentation. Of these, K. humilis and L. farraginis are rarely detected during regular wine fermentation. The identified functional species could be used to control typical aromatic characteristics of Msalais.

Fungal dynamic during apricot wine spontaneous fermentation and aromatic characteristics of Pichia kudriavzevii for potential as starter.

Microbial activity during spontaneous fermentation in alcoholic beverages have driven in developing the chemical and aromatic characteristic of products but not clear in apricot wines. We have characterised the composition of fungal communities and volatile metabolites in apricot wine spontaneous fermentation among two Shaanxi regions. Results showed that Aureobasidium, Alternaria, Pichia and Saccharomyces, were the dominant fungi in apricot wine fermentation. A total of 80 volatiles including esters, alcohols, acids and terpenes were detected from two apricot wines. Their correlations suggested that apricot wine aroma was mainly affected by Pichia kudriavzevii, rather than Saccharomyces cerevisiae we commonly considered. Furthermore, reinforced inoculation of P. kudriavzevii LQD20 has exhibited the commendable potential in enhancing sensory qualities. The results of this study provide fundamental information of the indigenous microbiota in microbial dynamic during apricot wine fermentation, which would be helpful in exploiting the strains with potential for industrial use as starter cultures.