Wine Fermentation Research Articles

Flavor Characteristics of Navel Orange Wine Fermented by Saccharomyces cerevisiae SC-125 and Angel Yeast SY

This research utilized Jintang navel oranges as the primary raw material, and employed two distinct yeast strains, Saccharomyces cerevisiae SC-125 and Angel yeast SY, for a dual fermentation approach. Employing single-strain fermentation as the control, this study aims to ascertain the physicochemical markers, alterations in organic acids and amino acids, alongside the antioxidant properties throughout the fermentation process, all within an optimized environment. The characterization of flavor compounds in the navel orange wines subjected to diverse yeast strains and mixed fermentation was conducted using headspace solid-phase microextraction coupled with gas chromatography–mass spectrometry (HP-SPME/GC-MS). This method facilitated the identification of flavor compound types and concentrations. Moreover, electronic sensory systems including electronic noses and electronic eyes were harnessed to discern distinctions among various navel orange wines. Through these techniques, the research aimed to elucidate the variances induced by different yeast strains during both individual and mixed fermentation processes, shedding light on their impacts on the ultimate quality of navel orange wines.

Microbial Diversity of Marula Wine during Spontaneous Fermentation

Marula wine is produced from ripe fruits of the Sclerocarya birrea subspecies caffra tree through spontaneous fermentation. A few culture-based studies have shown that the fermentation is largely driven by yeasts, although, in the early stages, some lactic acid bacteria (LAB) and acetic acid bacteria may be detected. Some of the microbes may produce undesirable metabolites that lead to the spoilage and short shelf life of the wine. However, there is generally limited information on the microbial composition and its contribution to the chemical characteristics of the resultant marula wine. The aim of this study was to characterise the microbial population of marula wine from different localities in the Limpopo province, South Africa. MALDI-TOF and amplicon sequencing technique were used to identify microbial strains and to determine their diversity and changes in the different stages of fermentation. The phylogenetic relationships of LAB and S. cerevisiae were analysed using multilocus sequence typing. Bacterial species that were common in the different marula wines included Gluconobacter oxydans, Lactiplantibacillus plantarum, Levilactobacillus brevis, Lacitilactobacillus nagelii, Lentilactobacillus kefiri and Lentilactobacillus parabuchneri, and the yeasts were Hanseniaspora guiliermondii, Saccharomyces cerevisiae, Rhodotorula mucilaginosa and Pichia kudriavzevii. The MLST data indicated common microbiota from different marula wines with low intraspecific diversity, suggesting that the LAB and S. cerevisiae strains that are mainly responsible for the spontaneous fermentation of marula wine are similar irrespective of the geographical differences and production preferences.

Mixed biofilm formation by Oenococcus oeni and Saccharomyces cerevisiae: A new strategy for the wine fermentation process

Bacterial biofilms have attracted much attention in the food industry since this phenotype increases microbial resistance to environmental stresses. In wine-making, the biofilm produced by Oenococcus oeni is able to persist in this harsh environment and perform malolactic fermentations. Certain viticultural practices are interested in the simultaneous triggering of alcoholic fermentation by yeasts of the species Saccharomyces cerevisiae and malolactic fermentation by lactic acid bacteria. As yet, no data is available on the ability of these micro-organisms to produce mixed biofilms and promote fermentations. Here, the ability of S. cerevisiae and O. oeni to form mixed biofilms on different surfaces found in vinification was observed and analyzed using scanning electron microscopy experiments. Then, following co-inoculation with biofilm or planktonic cells microvinifications were carried out to demonstrate that the mixed biofilms developed on oak allow the efficient completion of fermentations because of their high resistance to stress. Finally, comparisons of the different metabolic profiles obtained by LC-MS were made to assess the impact of the mode of life of biofilms on wine composition.

Strong ethanol- and frequency-dependent ecological interactions in a community of wine-fermenting yeasts

Natural wine fermentation depends on a complex consortium of native microorganisms rather than inoculation of industrial yeast strains. While this diversity of yeasts can result in an increased repertoire of wine flavors and aromas, it can also result in the inhibition of Saccharomyces cerevisiae, which is uniquely able to complete fermentation. Understanding how yeast species interact with each other within the wine-fermenting community and disentangling ecological interactions from environmental impacts on growth rates, is key to developing synthetic communities that can provide the sensory benefits of natural fermentation while lowering the risk of stuck ferments. Here, we co-culture all pairwise combinations of five commonly isolated wine-fermenting yeasts and show that competitive outcomes are a strong function of ethanol concentration, with frequency-dependent bistable interactions common at low alcohol and an increasingly transitive competitive hierarchy developing as alcohol increases. We also show that pairwise outcomes are predictive of five-species community outcomes, and that frequency dependence in pairwise interactions propagates to alternative states in the full community, highlighting the importance of species abundance as well as composition. We also observe that monoculture growth rates are only weakly predictive of competitive success, highlighting the need to incorporate ecological interactions when designing synthetic fermenting communities.

An introduction to modelling through a microbial interaction application

This paper describes a teaching experiment in a Numerical Methods course for Master of Science students. The experiment uses scientific papers to develop modelling studies in the context of wine fermentation microbial interactions. The course involves theoretical and laboratory classes that focus on implementing numerical methods using Matlab for Initial Value Problems and Boundary Value Problems. The students are asked to formalise the mathematical model and build their own experiments using the information provided in the papers. Additionally, a parameter estimation experiment is organised, which involves generating synthetic data and computing noisy data to estimate the natural death rate of sensitive yeast. The results show that data noise significantly affects the parameter estimate and that scaling the data can help reduce the impact of measurement errors. The presented results can be used to investigate other possible assignments, such as how the evaluation of the Jacobian affects the estimation performance and compare different optimisation algorithms.

Multi-step screening of suitable Saccharomyces cerevisiae strain for lemon wine brewing

Currently, most fruit wines are fermented with commercial wine yeasts or universal Saccharomyces cerevisiae strains, which leads to the problems of thin taste, insufficient flavor, and lack of typicality of fruit wine. In this study, one S. cerevisiae strain (NM-8) was isolated from the spontaneous fermentation broth of lemon, and its fermentation characteristics for lemon wine were compared with three commercial S. cerevisiae strains. The results showed that S. cerevisiae NM-8 displayed a good acidity tolerance under pH 3.2 and 2.8, which reached the maximum cell value during lemon wine fermentation. In addition, the lemon wine sample fermented with NM-8 contained more ascorbic acid (48.22 mg/L), sorbitol (0.96 g/L), and glycerin (4.44 g/L), which performed positive effects on the smoothness and sweetness of lemon wine. Moreover, both its total flavonoid content and DPPH radical scavenging activity were the highest, which were 320.72 mg RE/L (expressed as rutin equivalent) and 66.33%, respectively. Meanwhile, Gas Chromatography-Mass Spectrometry, Gas Chromatography-Ion Mobility Spectrometry, and sensory evaluation were used for the comprehensive analysis of the flavor compounds of four lemon wines. It showed that the lemon wine fermented with NM-8 had the highest sensory score, possibly due to the abundance of flavor compounds and their higher odor activity value. In conclusion, the screened strain S. cerevisiae NM-8 isolated from lemon surroundings with stronger acid resistance was able to brew excellent lemon wine with not only higher taste evaluation score but also stronger antioxidant activity, indicating that NM-8 showed substantial advantages in producing lemon wine.

Contribution of trehalose to ethanol stress tolerance of Wickerhamomyces anomalus

BackgroundThe ascomycetous heterothallic yeast Wickerhamomyces anomalus (WA) has received considerable attention and has been widely reported in the winemaking industry for its distinctive physiological traits and metabolic attributes. An increased concentration of ethanol during ethanol fermentation, however, causes ethanol stress (ES) on the yeast cells. Trehalose has been implicated in improving survival under various stress conditions in microorganisms. Herein, we determined the effects of trehalose supplementation on the survival, differentially expressed genes (DEGs), cellular morphology, and oxidative stress tolerance of WA in response to ES.ResultsThe results indicated that trehalose improved the survival and anomalous surface and ultrastructural morphology of WA. Additionally, trehalose improved redox homeostasis by reducing the levels of reactive oxygen species (ROS) and inducing the activities of antioxidant enzymes. In addition, DEGs affected by the application of trehalose were enriched in these categories including in gene expression, protein synthesis, energy metabolism, and cell cycle pathways. Additionally, trehalose increased the content of intracellular malondialdehyde (MDA) and adenosine triphosphate.ConclusionsThese results reveal the protective role of trehalose in ES mitigation and strengthen the possible uses of WA in the wine fermentation sector.

Exploring the Potential of Non-Conventional Yeasts in Wine Fermentation with a Focus on Saccharomycopsis fermentans

Despite the increasing number of publications on non-conventional yeasts (NCYs), many areas in this field remain poorly understood, making the examination of these strains important for determining their potential in wine fermentations. The amino acid metabolic pathways involved, particularly the catabolic Ehrlich pathway but also anabolic pathways such as the leucine biosynthesis pathway, are crucial for producing high-value aroma compounds that contribute to the final flavour of wine. We examined the potential use of Saccharomycopsis fermentans in wine fermentations. We selected mutant strains resistant to the toxic compound trifluoro-leucine (TFL), verified mutations in the SfLEU4 gene, and characterized the ability of the resulting strains to contribute to fermentation bouquets. Resistance to TFL relieves feedback inhibition in the leucine biosynthesis pathway and resulted in increased leucine biosynthesis. Concomitantly, the S. fermentans TFL-resistant mutants generated increased amounts of isoamyl alcohol and isovalerate during wine fermentation. Selection of TFL-resistant strains thus provides a generally applicable strategy for the improvement in NCYs and their utilization in co-fermentation processes for different grape must varieties.

Optimization of the Ginkgo Wine Fermentation Process and Influence of Fermentation Starter Types on the Brewing Flavor

Ginkgo biloba seed (GBS) contains rich nutrients, such as starch, protein, oil, and trace components, such as flavonoids and terpene lactones. Due to its high protein content, it can be used as a raw material for fermentation and brewing. In this study, GBS was selected as the object of a fermentation process optimization test. Six kinds of fermentation starter were selected to brew ginkgo wine. The results showed that different fermentation starters have significant impacts on the composition of the wine. The yeast group had higher total sugar content and comprehensive evaluation scores than the Jiuqu group, while the total acid and total free amino acid contents showed the opposite result. The total flavonoid and total terpene lactone contents of the yeast group were 21.0% and 12.8% higher than those of the Jiuqu group, respectively. However, the 4′-O-methylpyridoxine (MPN) and 4′-O-methylpyridoxine-5′-glucoside (MPNG) contents of the yeast group were also 12.6% and 2.3% higher than those of the Jiuqu group, respectively. The common volatile components in the two groups of samples were isoamyl alcohol, phenethyl alcohol, ethyl octanoate, and phenethyl acetate. The antioxidant capacity of ginkgo wine fermented by yeast was significantly higher than that of the Jiuqu group sample.

Fermentation and bio-functions of sake and Chinese rice wine: Implications for 'healthy-alcoholic industry'

Traditional low-alcoholic beverages were promoted to be healthy drinks with multiple bio-functions. Research into Japanese sake and Chinese rice wine (CRW) in terms of the preparation process, bacteria diversity, authentic quality control and bio functions is of significance. Japanese sake and CRW are representative alcoholic beverages which were proven to bring health benefits. For instance, sake was found to contain bio-functional components of CRW were found to obtain antioxidant activities. In this article, the production mechanisms and their bioactive components in Japanese sake and CRW were discussed. Red yeast rice is made by fermenting the rice with Monascus. However, commercial lovastatin (a structure that similar to monacolin K) is recently reported to be illegally added to common red yeast rice to meet drug quality standards, herein, there are many safety issues of rice wine, and it is especially important to dress the authentication assessment of the CRW. A new era of CRW as a low-alcoholic healthy beverage is coming. Prospects for the future development of CRW, with an emphasis on the absorption of the successful regulation experience from Japanese sake productions which are with high reputations worldwide, are presented.

Unveiling the power of adding sterols in wine: Optimizing alcoholic fermentation with strategic management

Excessive grape must clarification can result in sluggish alcoholic fermentation and sometimes alcoholic stuck fermentation, because of the lack of sterols for the yeasts growth. To avoid this risk, addition of sterols (ergosterol or phytosterols) can be performed, resulting in higher Saccharomyces cerevisiae viability and shorter fermentation duration. However, no dedicated study was implemented to evaluate the efficiency of different strategies of sterol management (considering sterol type, added concentration and timing of addition) during wine fermentation. So, first, to evaluate whether the response of wine yeast strains to sterol nutrition was similar according to the type and the concentration of the sterol present in the initial must, it was studied the response of a set of 10 S. cerevisiae strains in a synthetic grape must with low, medium and high concentrations of ergosterol or phytosterols. Then, the impact of the timing of sterol addition was evaluated on 2 S. cerevisiae strains with opposite behaviours. This work confirmed previous results concerning the role of ergosterol and phytosterols but also revealed new findings in this field. At first, it was confirmed that ergosterol played an important role in improving the maintenance of viable cells towards the end of fermentation, particularly in sterols-limited situations, while phytosterols demonstrated an ability to reduce acetate and glycerol production. But, in a second part, our study sheds new light on the beneficial impact of sterol addition on amino acid assimilation in yeast, leading to an increase in maximum fermentation rate, biomass production and percentage of viable cells. However, the main novelty of this research work concerns the timing of ergosterol addition. This addition at the start of fermentation in a phytosterols-free synthetic must enabled faster fermentations, as well as higher fermentative aroma synthesis, compared to addition during stationary phase Even if the impact of ergosterol additions were relatively similar for both strains tested, notable differences were found concerning amino acid assimilation and biomass production, suggesting differences in the regulation of nitrogen metabolism between both strains. These findings provide new insights into our understanding of sterol role in enological fermentation. It offers a basis for both the development of innovative strategies for sterol management and the selection of wine yeast strains under sterol starvation.

The dynamics of physicochemical properties, microbial community, and flavor metabolites during the fermentation of semi-dry Hakka rice wine and traditional sweet rice wine.

The dynamics of physicochemical properties, microbial community and flavor metabolites during fermentation of two typical Hakka rice wine were investigated. Results showed that total sugar content was 136.83g/L in sweet rice wine, which almost 8 times higher than that in semi-dry rice wine. Its amino acid contents especially bitterness amino acids were also higher than those in semi-dry rice wine. Most organic acids in Hakka rice wine had the tendency of increase in initial stage of fermentation, following a decrease and finally being almost stable. A total of 131 volatiles including esters, alcohols, aldehydes, acids, ketones were detected. Pediococcus, Bacillus, Acinetobacter, Pantoea, Enterobacter and Lactobacillus were the dominant bacterial genera and Monascus, Saccharomyces, Rhizopus were the dominant fungal genera, which are strongly associated with the significant changes in flavor metabolites during Hakka rice wine fermentation. The obtained findings provided reference data for the optimization of Hakka rice wine fermentation.

커피발효물의 발효특성 및 항비만 효과

This study was conducted to investigate the fermentation characteristics and anti-obesity effects of acetic acid fermentation products of coffee wine. The live cell counts, soluble solids, pH and total acidity of the acetic acid unfermented coffee wine (AUFCW; day 0, before fermentation) were 6.35 log CFU/mL, 8.10 °Brix, 3.88, and 1.29%, respectively, while the acetic acid fermented coffee wine (AFCW; day 15, after fermentation) were 4.40 log CFU/mL, 8.57 °Brix, 3.07, and 7.45%, respectively. Pancreatic lipase inhibitory activity tended to increase as the acetic acid fermentation period increased. The anti-obesity effects of AFCW on 3T3-L1 cells, which was induced by MDI, were evaluated based on the lipid accumulation rate, leptin expression, and fat production-related gene expression (PPAR-γ and SREBP-1c) at the mRNA level. In the case of AFCW, the lipid accumulation rate and leptin expression were decreased to 69.37% and 50.20% at a concentration of 200 μg/mL, respectively, and the expression levels of PPAR-γ and SREBP-1c at the mRNA level were decreased to 79.89% and 48.81%, respectively. These results indicate that anti-obesity effect of acetic acid fermentation products could be increased by acetic acid fermentation of coffee wine.

Single nucleotide polymorphisms associated with wine fermentation and adaptation to nitrogen limitation in wild and domesticated yeast strains

For more than 20 years, Saccharomyces cerevisiae has served as a model organism for genetic studies and molecular biology, as well as a platform for biotechnology (e.g., wine production). One of the important ecological niches of this yeast that has been extensively studied is wine fermentation, a complex microbiological process in which S. cerevisiae faces various stresses such as limited availability of nitrogen. Nitrogen deficiencies in grape juice impair fermentation rate and yeast biomass production, leading to sluggish or stuck fermentations, resulting in considerable economic losses for the wine industry. In the present work, we took advantage of the “1002 Yeast Genomes Project” population, the most complete catalogue of the genetic variation in the species and a powerful resource for genotype-phenotype correlations, to study the adaptation to nitrogen limitation in wild and domesticated yeast strains in the context of wine fermentation. We found that wild and domesticated yeast strains have different adaptations to nitrogen limitation, corroborating their different evolutionary trajectories. Using a combination of state-of-the-art bioinformatic (GWAS) and molecular biology (CRISPR-Cas9) methodologies, we validated that PNP1, RRT5 and PDR12 are implicated in wine fermentation, where RRT5 and PDR12 are also involved in yeast adaptation to nitrogen limitation. In addition, we validated SNPs in these genes leading to differences in fermentative capacities and adaptation to nitrogen limitation. Altogether, the mapped genetic variants have potential applications for the genetic improvement of industrial yeast strains.

Succinic acid production by wine yeasts and the influence of GABA and glutamic acid

As a consequence of alcoholic fermentation (AF) in wine, several compounds are released by yeasts, and some of them are linked to the general quality and mouthfeel perceptions in wine. However, others, such as succinic acid, act as inhibitors, mainly of malolactic fermentation. Succinic acid is produced by non-Saccharomyces and Saccharomyces yeasts during the initial stages of AF, and the presence of some amino acids such as γ-aminobutyric acid (GABA) and glutamic acid can increase the concentration of succinic acid. However, the influence of these amino acids on succinic acid production has been studied very little to date. In this work, we studied the production of succinic acid by different strains of non-Saccharomyces and Saccharomyces yeasts during AF in synthetic must, and the influence of the addition of GABA or glutamic acid or a combination of both. The results showed that succinic acid can be produced by non-Saccharomyces yeasts with values in the range of 0.2–0.4 g/L. Moreover, the addition of GABA or glutamic acid can increase the concentration of succinic acid produced by some strains to almost 100 mg/L more than the control, while other strains produce less. Consequently, higher succinic acid production by non-Saccharomyces yeast in coinoculated fermentations with S. cerevisiae strains could represent a risk of inhibiting Oenococcus oeni and therefore the MLF.

Potential Risks of Tebuconazole during Wine Fermentation at the Enantiomer Level Based on Multiomics Analysis.

The enantioselectivity and potential risks of tebuconazole enantiomers (R-tebuconazole and S-tebuconazole) in wine fermentation were investigated in this study using Cabernet Sauvignon grapes. Tebuconazole was mainly degraded during the alcoholic fermentation stage, and no obvious transformation between R-tebuconazole and S-tebuconazole was observed. Selective degradation between these two enantiomers occurred, with R-tebuconazole degrading faster than S-tebuconazole. The residual tebuconazole inhibits glucose metabolism and the unsaturated fatty acid formation in the wine fermentation system and inhibits gene expression in the late phase of Saccharomycetales, affecting its cell wall formation. Overall, the findings highlight that R-tebuconazole exhibited a higher risk than S-tebuconazole in these processes. These insights are potentially exploitable to understand chiral pesticides at the enantiomer level using multiomics technology in food-processing systems.

A rapid and reliable method for the determination of Lactiplantibacillus plantarum during wine fermentation based on PMA-CELL-qPCR.

Real-time monitoring of microbial dynamics during fermentation is essential for wine quality control. This study developed a method that combines the fluorescent dye propidium monoazide (PMA) with CELL-qPCR, which can distinguish between dead and live microbes for Lactiplantibacillus plantarum. This method could detect the quantity of microbes efficiently and rapidly without DNA extraction during wine fermentation. The results showed that (1) the PMA-CELL-qPCR enumeration method developed for L. plantarum was optimized for PMA treatment concentration, PMA detection sensitivity and multiple conditions of sample pretreatment in wine environment, and the optimized method can accurately quantify 104-108 CFU/mL of the target strain (L. plantarum) in multiple matrices; (2) when the concentration of dead bacteria in the system is 104 times higher than the concentration of live bacteria, there is an error of 0.5-1 lg CFU/mL in the detection results. The optimized sample pretreatment method in wine can effectively reduce the inhibitory components in the qPCR reaction system; (3) the optimized PMA-CELL-qPCR method was used to monitor the dynamic changes of L. plantarum during the fermentation of Cabernet Sauvignon wine, and the results were consistent with the plate counting method. In conclusion, the live bacteria quantification method developed in this study for PMA-CELL-qPCR in L. plantarum wines is accurate in quantification and simple in operation, and can be used as a means to accurately monitor microbial dynamics in wine and other fruit wines.

Mosaic Genome of a British Cider Yeast.

Hybrid formation and introgressions had a profound impact on fermentative yeasts domesticated for beer, wine and cider fermentations. Here we provide a comparative genomic analysis of a British cider yeast isolate (E1) and characterize its fermentation properties. E1 has a Saccharomyces uvarum genome into which ~102 kb of S. eubayanus DNA were introgressed that replaced the endogenous homologous 55 genes of chromosome XIV between YNL182C and YNL239W. Sequence analyses indicated that the DNA donor was either a lager yeast or a yet unidentified S. eubayanus ancestor. Interestingly, a second introgression event added ~66 kb of DNA from Torulaspora microellipsoides to the left telomere of SuCHRX. This region bears high similarity with the previously described region C introgression in the wine yeast EC1118. Within this region FOT1 and FOT2 encode two oligopeptide transporters that promote improved nitrogen uptake from grape must in E1, as was reported for EC1118. Comparative laboratory scale grape must fermentations between the E1 and EC1118 indicated beneficial traits of faster consumption of total sugars and higher glycerol production but low acetic acid and reduced ethanol content. Importantly, the cider yeast strain produced high levels of fruity ester, including phenylethyl and isoamyl acetate.

Reducing higher alcohols by integrating indigenous Saccharomyces cerevisiae, nitrogen compensation, and chaptalization methods during fermentation of kiwifruit wine

The concentration of higher alcohols in kiwifruit wine is often excessive, posing the risk of toxic effects on the health of drinkers. To lower the higher alcohol content in kiwifruit wine, this study tested five indigenous S. cerevisiae strains, two types of nitrogen sources (inorganic and organic), and five chaptalization methods. The results showed that the total higher alcohol production of three versions of resulting kiwifruit wines: (i) fermented by S. cerevisiae LFN524, (ii) adding 300 mg/L diammonium phosphate (DAP), using the Th-Tw-S chaptalization strategy, were decreased by 32%, 43%, and 26%, respectively. Integrating the above technologies, that is, fermentation by S. cerevisiae LFN524, the addition of 300 mg/L DAP, and use of Th-Tw-S chaptalization strategy, for pilot-scale kiwifruit wine production, showed a 52% reduction in total higher alcohol production (222.00 ± 24.91 mg/L) and a 14% reduction in total acidity production (13.32 ± 0.06 g/L). In pilot-scale kiwifruit wine, sensory analysis showed that with the reduction of higher alcohol content, the typical aromas of kiwifruit wine became more prominent, resulting in a purer aroma of kiwifruit wine. Taken together, the results of this research provide a viable means for producing lower-higher-alcohol kiwifruit wines.

Red Wine Fermentation Alters Grape Seed Morphology and Internal Porosity

Red Wine Fermentation Alters Grape Seed Morphology and Internal Porosity