Wine Fermentation Research Articles

Improving effects of three selected co-pigments on fermentation, color stability, and anthocyanins content of blueberry wine

The effects of caffeic acid, syringic acid, and quercetin co-pigments on fermentation, color changes, and anthocyanins stability of blueberry wine were evaluated. The co-pigmented blueberry wines exhibited a higher alcohol and titratable acidity, and a lower sugar content. This was accompanied by a lower L* and a* and a greater b*, a significant shift in the λmax and an increase in absorbance value at λmax, altogether, indicating a darker and vivid bluish red color of blueberry wines. Total anthocyanins content in the wine samples with co-pigments were significantly higher with a greater stability after 20 days of post-fermentation. The malvidin glucoside and cyanidin glucoside exhibited the most stability in co-pigmented blueberry wines whilst none of the used co-pigments were able to protect cyanidin galactoside. We speculate that co-pigmentation with caffeic acid, syringic acid, or quercetin is an effective way to produce blueberry wine with a higher nutritional and sensory quality.

Metabolic Modeling of Wine Fermentation at Genome Scale.

Wine fermentation is an ancient biotechnological process mediated by different microorganisms such as yeast and bacteria. Understanding of the metabolic and physiological phenomena taking place during this process can be now attained at a genome scale with the help of metabolic models. In this chapter, we present a detailed protocol for modeling wine fermentation using genome-scale metabolic models. In particular, we illustrate how metabolic fluxes can be computed, optimized and interpreted, for both yeast and bacteria under winemaking conditions. We also show how nutritional requirements can be determined and simulated using these models in relevant test cases. This chapter introduces fundamental concepts and practical steps for applying flux balance analysis in wine fermentation, and as such, it is intended for a broad microbiology audience as well as for practitioners in the metabolic modeling field.

Making wine in Pañul’s craft pottery vessels: a first approach in the study of the dynamic of alcoholic fermentation and wine volatile composition

Traditional winemaking in amphora-like clay vessels is one of the oldest known methods of wine production. Currently, some wine producers have readopted traditional winemaking methods to generate unique attributes that differentiate their products raising regional wine typicity. The aim of this research was to study the dynamic of alcoholic fermentation and volatile composition of ‘Carignan’ wines fermented into Pañul’s clay vessels and comparing them with the wines vinified into stainless-steel tanks. Density curve of the musts contained in the Pañul’s pottery vessels followed a similar trend than in the samples contained in the stainless-steel tanks. The temperatures of the must and the cap during alcoholic fermentation were lower in the Pañul’s pottery vessels than in the stainless-steel tanks in most of the evaluated days. Thus, clay vessels may provide temperature-regulating properties beneficing wine fermentation compared to stainless-steel tanks. Pañul’s clay vessels produced wines with higher terpenes,β-ionone and 2-phenylethyl alcohol content, and lower values of some individual higher alcohols, isoamyl acetate, lactones, and pH than the stainless-steel tanks. Therefore, the results suggest that Pañul’s pottery vessels favored increasing the terpene alcohols and other volatile compounds concentrations, in addition to decreasing certain higher alcohols and acetate esters contents such as benzyl alcohol and iso-amyl acetate. These outcomes may be of interest to ceramic producers and wine producers since they open a range of economic opportunities to diversify their products.

Automated Density Measurement With Real-Time Predictive Modeling of Wine Fermentations

Wine fermentation is traditionally monitored through manual measurements of density; however, such measurements become labor-intensive as the number of fermentations increases. Various <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">in situ</i> density measurement techniques are currently used in the wine industry; however, they have not been widely studied nor widely adopted. In this work, we combine <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">in situ</i> measurements of density based on differential pressure measurements with a wine kinetic model and parameter estimation routine to predict the progression of a 1500-L wine fermentation. Pressure transducers were mounted at three vertical positions, and the influence of sensor precision and vertical separation of the transducers was investigated. The transducer measurements were in agreement with the density of samples from a hand-held densitometer. The density measurements from the start of fermentation to 75, 100, 125, and 150 h were used to predict future fermentation behavior. The results show that the automated measurement methodology, combined with a wine kinetic model, can be used in commercial wineries to monitor and predict ongoing fermentations.

Biochemical processes during secondary fermentation of apple juice and storage of sparkling wines

Apple sparkling wines are characterized not only by the foamy and sparkling properties common to all wines of this type, but also by freshness and lightness of taste, which are the result of a harmonious combination of the taste qualities of fruit juice and its fermentation products against the background of low alcohol content and low oxidation. The aim of the study was to change the main physical and chemical parameters and the number of yeast cells during fermentation – deaeration and fermentation of apple juice and wine. The objects of research were winter varieties of apples Idared, Jonathan, Renet Simirenko, Florina, apple wine materials and finished wine. The chemical composition and quality of fruits and wine materials were determined according to generally accepted methods in winemaking. It has been established that during the day, the decrease in the R potential during deaeration of the fermentation mixture for apple cider occurs within the range of 8-20 mV, and the higher the initial potential, the more effective its reduction. In the first 3-5 days, a decrease in the R potential by an average of 50-71 mV was observed in all samples. Then the potential basically remained at this level without changes. Studies have shown that when fermenting natural fermented juice with freshly introduced wine yeast, the number of cells after 2 days increases by more than 2.7 times, and after 5 days – almost 4.5 times, reaching 31 million/ml. The most intensive reproduction of yeast is observed on the 2nd-3rd day of fermentation. At the same time, there is a sharp decrease of ammonia nitrogen, amine nitrogen and oxygen in the content. A decrease in the content of oxygen and peroxides, in turn, is accompanied by a significant decrease in the R potential of the fermenting must. After 5 days of fermentation, the number of yeast cells increases by 4.4 times with the full use of nitrogen nutrition, especially ammonia nitrogen, as well as oxygen. The increase in the initial alcohol content of the fermented juice to 8.5% vol. reduces the rate of yeast growth.

Effect of Issatchenkia terricola WJL-G4 on Deacidification Characteristics and Antioxidant Activities of Red Raspberry Wine Processing.

Our previous study isolated a novel Issatchenkia terricola WJL-G4, which exhibited a potent capability of reducing citric acid. In the current study, I. terricola WJL-G4 was applied to decrease the content of citric acid in red raspberry juice, followed by the red raspberry wine preparation by Saccharomyces cerevisiae fermentation, aiming to investigate the influence of I. terricola WJL-G4 on the physicochemical properties, organic acids, phenolic compounds and antioxidant activities during red raspberry wine processing. The results showed that after being treated with I. terricola WJL-G4, the citric acid contents in red raspberry juice decreased from 19.14 ± 0.09 to 6.62 ± 0.14 g/L, which was further declined to 5.59 ± 0.22 g/L after S. cerevisiae fermentation. Parameters related to CIELab color space, including L*, a*, b*, h°, and ∆E* exhibited the highest levels in samples after I. terricola WJL-G4 fermentation. Compared to the red raspberry wine pretreated without deacidification (RJO-SC), wine pretreated by I. terricola WJL-G4 (RJIT-SC) exhibited significantly decreased contents of gallic acid, cryptochlorogenic acid, and arbutin, while significantly increased contents of caffeic acid, sinapic acid, raspberry ketone, quercitrin, quercetin, baicalein, and rutin. Furthermore, the antioxidant activities including DPPH· and ABTS+· radical scavenging were enhanced in RJIT-SC group as compared to RJO-SC. This work revealed that I. terricola WJL-G4 had a great potential in red raspberry wine fermentation.

Differential Response of the Proteins Involved in Amino Acid Metabolism in Two Saccharomyces cerevisiae Strains during the Second Fermentation in a Sealed Bottle

The traditional method for sparkling wine making consists of a second fermentation of a base wine followed by ageing in the same bottle that reaches the consumers. Nitrogen metabolism is the second most important process after carbon and takes place during wine fermentation by yeast. Amino acids are the most numerous nitrogen compounds released by this process. They contribute to the organoleptic properties of the wines and, therefore, to their sensory quality. The main objective of this study is to compare the differential proteomic response of amino acid metabolism, specifically their proteins and their interactions in the G1 strain (unconventional yeast) during sparkling wine production versus the conventional P29 strain. One of the new trends in winemaking is the improvement of the organoleptic diversity of wine. We propose the use of unconventional yeast that shows desirable characteristics for the industry. For this purpose, these two yeasts were grown at sealed bottle conditions for the second fermentation (Champenoise method). No differences were obtained in the middle of fermentation between the yeast strains. The number of proteins identified, and the relationships established, were similar, highlighting lysine metabolism. At the end of the second fermentation, the difference between each strain was remarkable. Hardly any proteins were identified in unconventional versus conventional yeast. However, in both strains, the metabolism of sulfur amino acids, methionine, and cysteine obtained a greater number of proteins involved in these processes. The release of these amino acids to the medium would allow the yeast to balance the internal redox potential by reoxidation of NADPH. This study is focused on the search for a more complete knowledge of yeast metabolism, specifically the metabolism of amino acids, which are key compounds during the second fermentation.

Genome-edited Saccharomyces cerevisiae strains for improving quality, safety, and flavor of fermented foods

While Cas9-based genome editing enabled precise and sophisticated genetic perturbations in conventional and non-conventional yeast strains, its applications for food fermentations have been extremely limited. In order to improve quality and flavor of various yeast-fermented foods, we isolated and engineered a diploid or polyploid Saccharomyces cerevisiae strain (N1) which exhibits robust sugar fermentation, strong acid tolerance, and rapid gas production from Korean Nuruk. First, RGT2 and SNF3 coding for glucose sensors were deleted to increase respiration. A bread dough fermented with the N1ΔRGT2ΔSNF3 strain showed an 18% increased volume due to higher carbon dioxide production. Second, ASP3 coding for asparaginase was overexpressed and URE2 coding for a transcriptional factor of nitrogen catabolite repression (NCR) was deleted to increase asparagine consumption. When the N1ΔURE2::PGPD-ASP3 strain was applied to a potato dough, asparagine was rapidly depleted in the dough, resulting in potato chips with negligible amounts of acrylamide. Third, the N1ΔURE2 strain was utilized to increase levels of the amino acids which provide a savory taste during rice wine fermentation. The above genome-edited yeast strains contain no heterologous DNA. As such, they can be used to improve fermented foods with no subjection to GM regulation.

Recycling and Conversion of Yeasts into Organic Nitrogen Sources for Wine Fermentation: Effects on Molecular and Sensory Attributes

Organic nitrogen plays a significant role in the fermentation performance and production of esters and higher alcohols. This study assessed the use of yeast protein hydrolysate (YPH) as a nitrogen source for grape must fermentation. In this study, we prepared an enzymatic protein hydrolysate using yeasts recovered from a previous fermentation of wine. Three treatments were performed. DAP supplementation was used as a control, while two YPH treatments were used. Low (LDH) and high degrees of hydrolysis (HDH), 3.5% and 10%, respectively, were chosen. Gas chromatography and principal component analysis indicated a significant positive influence of YPH-supplementations on the production of esters and higher alcohols. Significantly high concentrations of 3-methyl-1-penthanol, isoamyl alcohol, isobutanol, and 2-phenylethanol were observed. Significant odorant activity was obtained for 3-methyl-1-pentanol and ethyl-2-hexenoate. The use of YPH as nitrogen supplementation is justified as a recycling yeasts technique by the increase in volatile compounds.

Understanding metabolic perturbations in palm wine during storage using multi-platform metabolomics

The metabolic perturbations in palm wine under five (0, 12, 24, 48, 72 h) storage intervals was studied using NMR and LC-HRMS. From 100 (25 from NMR and 75 from LC-HRMS) identified metabolites, 9 and 10 from NMR and LC- HRMS were identified as differential metabolites on storage which includes sugars, organic acids, polyols, and amino acids. The sugars and organic acids were significantly altered upon palm wine storage as organic acids dependent on sugars for a carbon source in energy metabolism. This also confirms from the change of pH from 4.35 to 3.26 during storage. The MetPA analysis revealed that, five metabolic pathways (starch and sucrose metabolism, pyruvate metabolism, sulphur metabolism, and galactose metabolism from NMR; TCA cycle and galactose metabolism from LC- HRMS) were altered during palm wine storage. In conclusion, the study has shown the potential of two complementary analytical tools (NMR & LC-HRMS) in identifying a large pool of metabolites and thus, reveals the alterations in palm wine during successive fermentation. The present study finds application in exploring its sensory quality for public health and for commercialization. Further, it illustrats the role of organic acids and sugars in the fermentation of palm wine during storage.

A new approach to predicting the extraction of malvidin-3-glucoside during red wine fermentation at industrial-scale

Red wine quality is largely determined by the concentration of phenolic compounds such as anthocyanins that are extracted from skins and seeds during alcoholic fermentation. As such, the ability to control this extraction process is a key consideration for winemakers. Current mathematical models based on regression analysis methods that are used to describe phenolic extraction during fermentation can provide insight into the effect of changing process conditions, however their use as predictive tools for process control and management of future fermentation scenarios is limited. In this study, red wine fermentations undertaken at a large commercial winery are compared with simulations of malvidin-3-glucoside extraction (the predominant red wine anthocyanin), using a first principles mass-transfer model with incorporated response surface equations for calculating relevant mass transfer parameters throughout fermentation. In general, the model employed to simulate this mass transfer process showed consistent extraction patterns to that measured experimentally in commercial large-scale fermentations, and displayed good predictive capabilities for malvidin-3-glucoside concentrations at the latter stages of fermentation, highlighting its potential usefulness as a new tool for quality management and process control during winemaking.

Impact of serine and serine synthesis genes on H2S release in Saccharomyces cerevisiae during wine fermentation

Excessive hydrogen sulfide (H2S) during fermentation causes undesirable sensory properties in wine. In yeast, serine functions as a precursor in the biosynthesis of S-containing compounds, which facilitates H2S consumption. To investigate the effect of serine on H2S release and the underlying mechanism, extracellular and intracellular serine levels were separately increased under fermentation conditions. The results show that, although the abundance of extracellular serine was ineffective in decreasing H2S levels, increased levels of intracellular serine levels from SER1 and SER2 overexpression reduced H2S release through increased consumption of sulfur metabolites. In contrast, SER33 overexpression significantly increased H2S release, and the metabolites and gene expression profile of the sulfur assimilation pathway indicates that SER33 regulated MET17, which mediated H2S release. Our study revealed valuable insights on the relationship between serine levels and H2S release, and may be helpful in understanding the H2S regulation mechanism in yeast during fermentation.

The effects of cell-cell contact between Pichia kluyveri and Saccharomyces cerevisiae on amino acids and volatiles in mixed culture alcoholic fermentations

This study used a double-compartment fermenter to assess yeast growth, fermentation activity, and aroma production in response to cell-cell contact during mixed culture fermentation of Pinot noir grape must with Pichia kluyveri and Saccharomyces cerevisiae. Furthermore, amino acids were analyzed in order to study yeast interactions and possible reasons for aroma modulation as a response to cell-cell contact. Our results show that cell-cell contact between the two yeasts decreased cell viability of each yeast during mixed culture fermentation, and that it increased acetate and ethyl ester production and decreased varietal volatile levels. Moreover, it increased the consumption of glutamic acid and the biosynthesis of some specific amino acids related to cell growth, mainly histidine, glycine and proline, while suppressing the production of higher alcohols through the Ehrlich pathway. These results may contribute to an improved understanding, and thus control, of aroma production in mixed culture wine fermentations.

Effects of the addition of thermostable α-amylase on the physicochemical and antioxidant properties of extrusion-pretreated Apios fortunei used for yellow wine fermentation

Extrusion-pretreated Apios fortunei was used for yellow wine fermentation. To investigate the effect of thermostable α-amylase on the physicochemical and antioxidant properties of extruded A. fortunei, we used different enzyme concentrations (0–5‰). Enzymatic extrusion increased the degree of gelatinization (84.23–99.99%), water solubility index (28.09–62.75%), reducing sugar content (74.82–263.39 mg/g) and decreased water absorption index (3.25–2.09 g/g) and viscosity (<20 cP) of A. fortunei, these may be beneficial for fermentation. X-ray diffraction and Fourier transform infrared spectroscopy detected that the ordered degree of starch structure decreased with increased enzyme concentration. Molecular-weight analysis indicated that enzyme concentrations of more than 0.5‰ had limited promotion on starch degradation. Scanning electron microscopy observed the eroded surface and holes caused by enzymolysis in enzymatically extruded samples. Enzymatic extrusion increased the phenolic content and antioxidant properties of the samples. Relatively high fermentation efficiency (74.23%) and antioxidant properties (75.87, 76.21 and 203.32 mg of Trolox equivalents/L for DPPH, ABTS and FRAP values, respectively) were observed in wines fermented by extruded samples with 5‰ enzyme. The results indicated that the advantages of enzymatic extrusion in starch degradation and improving the antioxidant properties of A. fortunei could be extended to yellow wine fermentation.

Isolation and selection of yeasts from soursop Annona muricata for wine fermentation

Wine is a healthy drink and is becoming more diverse thanks to the substances with high biological activity and fully preserved the antioxidant capacity in the fruit after fermentation by yeast. This study aims to isolate yeasts that are capable of soursop fermentation. There were eight yeast strains isolated, in which five strains of yeasts NM1.1, NM1.2, NM2.1, NM3.1, NM3.2 are capable of fermenting soursop wine. Wine product after fermentation using strain NM1.1 with initial conditions of 22ºBrix, pH 4.5, supplemented yeast 1% (w/v) at room temperature (28-30ºC), in twelve-day, produced the ethanol content 10% v/v, methanol 1.304 g/l, and SO2 10.9 mg/l that meet Vietnamese standards (QCVN 6-3:2010/BYT).

Molecular adaptation response of Oenococcus oeni in non-Saccharomyces fermented wines: A comparative multi-omics approach

Oenococcus oeni is the main agent responsible for malolactic fermentation (MLF) in wine. This usually takes place in red wines after alcoholic fermentation (AF) carried out by Saccharomyces cerevisiae. In recent years, there is an increasing interest in using non-Saccharomyces yeast, usually in combination with S. cerevisiae, to improve wine quality. Current studies report a stimulatory effect of non-Saccharomyces on MLF, generally related to a decrease in the inhibitor compounds found in wine. In this work, we followed a comparative multi-omics approach, including transcriptomic and proteomic analysis, to study the molecular adaptation of O. oeni in wines fermented with Torulaspora delbrueckii and Metschnikowia pulcherrima, two of the most frequently used non-Saccharomyces, in sequential inoculation with S. cerevisiae. We compared the results to the adaptation of O. oeni in S. cerevisiae wine to determine the main changes arising from the use of non-Saccharomyces. The duration of MLF was shortened when using non-Saccharomyces, to half the time with T. delbrueckii and to a quarter with M. pulcherrima. In this work, we observed for the first time how O. oeni responds at molecular level to the changes brought about by non-Saccharomyces. We showed a differential adaptation of O. oeni in the wines studied. In this regard, the main molecular functions affected were amino acid and carbohydrate transport and metabolism, from which peptide metabolism appeared as a key feature under wine-like conditions. We also showed that the abundance of Hsp20, a well-known stress protein, depended on the duration time. Thus, the use of non-Saccharomyces reduced the abundance of Hsp20, which could mean a less stressful wine-like condition for O. oeni.

3D-Printed Liquid Cell Resonator with Piezoelectric Actuation for In-Line Density-Viscosity Measurements.

The in-line monitoring of liquid properties, such as density and viscosity, is a key process in many industrial areas such as agro-food, automotive or biotechnology, requiring real-time automation, low-cost and miniaturization, while maintaining a level of accuracy and resolution comparable to benchtop instruments. In this paper, 3D-printed cuboid-shaped liquid cells featuring a rectangular vibrating plate in one of the sides, actuated by PZT piezoelectric layers, were designed, fabricated and tested. The device was resonantly excited in the 3rd-order roof tile-shaped vibration mode of the plate and validated as a density-viscosity sensor. Furthermore, conditioning circuits were designed to adapt the impedance of the resonator and to cancel parasitic effects. This allowed us to implement a phase-locked loop-based oscillator circuit whose oscillation frequency and voltage amplitude could be calibrated against density and viscosity of the liquid flowing through the cell. To demonstrate the performance, the sensor was calibrated with a set of artificial model solutions of grape must, representing stages of a wine fermentation process. Our results demonstrate the high potential of the low-cost sensor to detect the decrease in sugar and the increase in ethanol concentrations during a grape must fermentation, with a resolution of 10 µg/mL and 3 µPa·s as upper limits for the density and viscosity, respectively.

Assessment of the lysogenic status in the lactic acid bacterium O. oeni during the spontaneous malolactic fermentation of red wines

After alcoholic fermentation, most wines undergo malolactic fermentation (MLF), driven by the lactic acid bacterium Oenococcus oeni, which improves their organoleptic properties and microbiological stability. Prophages were recently shown to be notably diverse and widely disseminated in O. oeni genomes. Such in silico predictions confirmed previous cultivation-based approaches which showed frequent lysis of strains upon treatment with the inducing agent mitomycin C. Both strategies used to assess lysogeny in the species were so far applied to a number of strains collected from distinct countries, wineries, cepages and fermentation processes. Results may not therefore be representative of the lysogenic population in natural communities driving the MLF during winemaking. Here we report the prevalence of lysogeny during winemaking in three wineries in the Bordeaux area. The dominant LAB population was collected in 11 red wines upon completion of MLF. Using VNTR and prophage typing analyses, our data confirm the presence of lysogens in the population driving the spontaneous MLF in all tested wines, although lysogeny rates varied across wineries. Higher prevalence of lysogeny was associated to a reduced diversity in VNTR profiles, the dominance of a few prophage-types and presence of some bacterial genetic backgrounds that were particularly prone to lysogenization.

Effects of different vinification technologies and yeasts on qualitative parameters and terpene compounds of Sauvignon Blanc wines

Abstract Sauvignon Blanc represents an important grape variety. The wine made from this variety is known to have a wide range of aroma profiles from nettles to tropical fruits. Beside the raw material quality (grapes), the quality of wines can be fundamentally influenced by the technological conditions applied in the wine making process. Yeast and other microorganisms play a key role in the formation of metabolites during alcoholic fermentation. In this study, the effects of autochthonous or selected wine yeasts (Saccharomyces cerevisiae) and fermentation temperatures (15 °C and 19 °C) were tested on major monoterpenes contents of wines during the period 2016–2017. The obtained values show that the highest contents of linalool (24.36 μg L−1) and hotrienol (11.84 μg L−1) were determined in wine samples produced with active (selected) wine yeast at lower temperature. Sensory evaluation results indicated that monoterpenes can have a positive effect on the overall sensory quality of Sauvignon Blanc wines, despite the fact that their determined concentrations in the evaluated samples were not higher than their threshold values.

Biotechnological Approaches to Lowering the Ethanol Yield during Wine Fermentation.

One of the most prominent consequences of global climate warming for the wine industry is a clear increase of the sugar content in grapes, and thus the alcohol level in wines. Among the several approaches to address this important issue, this review focuses on biotechnological solutions, mostly relying on the selection and improvement of wine yeast strains for reduced ethanol yields. Other possibilities are also presented. Researchers are resorting to both S. cerevisiae and alternative wine yeast species for the lowering of alcohol yields. In addition to the use of selected strains under more or less standard fermentation conditions, aerobic fermentation is increasingly being explored for this purpose. Genetic improvement is also playing a role in the development of biotechnological tools to counter the increase in the wine alcohol levels. The use of recombinant wine yeasts is restricted to research, but its contribution to the advancement of the field is still relevant. Furthermore, genetic improvement by non-GMO approaches is providing some interesting results, and will probably result in the development of commercial yeast strains with a lower alcohol yield in the near future. The optimization of fermentation processes using natural isolates is, anyway, the most probable source of advancement in the short term for the production of wines with lower alcohol contents.