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Copyright of Food & Fermentation Industries is the property of Food & Fermentation Industries and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

With deeper insights into the enology characteristics of Oenococcus oeni and Tactiptantibacittus ptantarum, The co-inocutation strategy has been gradually explored in malotactic fermentation (MTF). Indigenous O. oeni SD2a ( OeSD2a) and T. ptantarum XJ25 ( TpXJ25) were used for Cabernet Sauvignon and Cabernet Gernischt wines in this study. The dynamic changes of biomass and organic acids during MTF were monitored, composition and content of aroma compounds were also determined after MTF. Results demonstrated that the utitization of sequential inoculation significantly enhanced the degradation efficiency of malic acid and enriched the wines' aroma. The final degradation of malic acid was observed to be higher in each sequential inoculation fermentation group compared to the simultaneous inoculation group ( the highest was 98. 21% in Cabernet Gernischt wine and 99. 24% in Cabernet Sauvignon wine) . The inoculation sequence of (0 h) OeSD2a + ( 24 h) TpXJ25 exhibited the most optimal performance in aroma compounds synthesis, resulting in the highest total aroma concentration after MTF (486.72 mg/L in Cabernet Gernischt wine, 504.24 mg/L in Cabernet Sauvignon wine). The contents of ethyl nonanoate, ethyl laurate, and α-terpinenol were significantly increased, which improved the aroma performance of the wine samples. Therefore, the selection of the appropriate inoculation sequence is crucial in co-fermentation conditions to MTF enhance efficiency and improve wine aroma quality. [ABSTRACT FROM AUTHOR]

In wine, lactic acid bacteria (LAB) are responsible for the bioconversion of malic acid to lactic acid, malolactic fermentation that mainly aims at reducing wine acidity. Two LAB strains isolated from the red wine microbiota (Oenococcus oeni 13-7 and Lactobacillus plantarum R1-1), were tested for their ability to exhibit the carbon catabolite repression (CCR) mechanism, that allows the rapid use of certain carbohydrates, over other carbon sources. Bacterial cells were inoculated in 0.1 M glycine buffer (pH 3.5), incubated at 30°C, with different carbohydrates (45 mM) and malic acid (45 mM). For both strains, the presence of glucose significantly inhibited malic acid metabolization (-60%), a similar effect being observed for galactose, mannose and maltose. The highest rate of malic acid conversion was shown in fructose/malate medium. Obtained results showed that malolactic strains can control the utilization of carbon sources via CCR, further studies being necessary to elucidate the mechanisms underlying this process. [ABSTRACT FROM AUTHOR]

Traditional sparkling wines are produced in a two-step sequence of alcoholic fermentations, followed by extended aging which is an influential factor for the final aroma profile. Traditionally, the second fermentation and aging are conducted in bottles over a minimum of 18 months, resulting in an aroma profile which is shaped by oxidative secondary metabolites like aldehydes, acids and fatty acid esters. In this study, a total of 29 traditional commercial sparkling wines from the categories Champagne, Cava, California Champagne, and others (Prosecco and Cremant) were analyzed. The objective was to determine the impact of microbial activity on the stylistic characteristics of traditional sparkling wines and allow winemakers to reproduce the specific fermentation conditions. The results indicate that malolactic fermentation plays an important role in Champagne and some Cavas, but not in the other sparkling wine categories. The metabolic activity of lactic acid bacteria results in an altered acid profile, amino acid utilization, and aroma production. While primary fermentation esters like phenylethyl acetate and isoamyl acetate are significantly reduced in Champagne and Cava, aroma compounds from secondary microbial activity like ethyl lactate and 2-acetyl-1-pyrroline are increased. This underlines the importance of diverse microbial activity of the characteristic style of traditional sparkling wines. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Chinese Institute of Food Science & Technology is the property of Journal of Chinese Institute of Food Science & Technology Periodical Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This study was conducted to confirm the effectiveness of kimchi starters (KSs) by investigating their growth characteristics. First, we assessed the growth characteristics of five lactic acid bacteria (LAB) strains (Lactococcus lactis WiKim0124; Companilactobacillus allii WiKim39; and Leuconostoc mesenteroides WiKim0121, WiKim33, and WiKim32) and assessed the effects of different parameters, including organic acids, salinity, acidity, and temperature, on the growth of these LAB. The findings showed that organic acids, particularly acetic and lactic acids that accumulated with the progress in fermentation, were the major players determining the microbial composition of kimchi and the growth of the KSs. Leuconostoc mesenteroides grew well in the presence of acetic and lactic acids than other starts, so it is confirmed that Leuconostoc mesenteroides can dominant in kimchi. In addition, malic acid, which is derived from kimchi ingredients, is used to induce malolactic fermentation by Lactobacillus species, and the progression of malolactic fermentation can be controlled through KSs. Our results suggest that KSs promote the production of organic acids, and the profiling of organic acids, as well as the progress of malolactic fermentation, can be controlled by selecting the suitable KS. Overall, this study demonstrates that kimchi fermentation can be controlled more effectively if the characteristics of KS are understood and used appropriately.

Malolactic fermentation (MLF) is known as the process responsible for the sensory profiles of wines which converts L-malic acid in the must into L-lactic acid. It takes place after the alcoholic fermentation with the activities of more than ten species of lactic acid bacteria (LAB) such as Pediococcus sp., Leuconostoc sp., Oenococcus sp. and Lactobacillus sp. However, the MLF performance depends on the LAB growth, which is influenced by the multi-stressors from the harsh environment of wine (low pH, a high alcoholic content, non-optimal growth temperatures, and growth-inhibitory substances from grape must and metabolites of yeast, …). Due to these challenging environmental factors, LAB were difficult to develop on wine must. This caused the inefficient conversion of L-Malate to L-lactate. Therefore, improving the malate degradation functionality of LAB with well-adapting to MLF conditions has been a key to have a well-balanced wine because several mechanisms for resisting wine conditions were developed in the wine LAB. This paper is to review, discuss, and appraise the current environmental stresses affecting LAB as well as the impact of these factors on the LAB's functionalities in grape must wine. It aims to state the art in improving the MLF efficiency and having an overview of some future trends in the winemaking.

This study aimed to investigate the impact of different strains of Lactiplantibacillus plantarum on malolactic fermentation (MLF), antioxidant activity, and aroma of ciders. A commercial strain of Saccharomyces cerevisiae and six indigenous L. plantarum strains were co-inoculated into apple juice to induce simultaneous alcoholic fermentation (AF) and MLF. The findings indicated that despite belonging to the same species, the different L. plantarum strains significantly differed (p

Bilberries (Vaccinium myrtillus) are the most common wild berries in Northern Europe. A substantial amount of the berries are picked with the objective to extract highly valued products such as anthocyanins. A smaller amount of the bilberries is used to make jams and drinks, and these are generally restricted to the domestic market. One reason is the sour taste, partly as a result of the high content of malic acid. By using certain strains of lactic acid bacteria with the ability to convert malic acid to lactic acid, the taste is predicted to be more pleasant. This process is called malolactic fermentation, and historically it has mostly been used in winemaking. After testing five different starter cultures, we identified that the strain, Lactiplantibacillus plantarum LP58, can rapidly convert malic acid to lactic acid without any loss of sugar or citric acid, which strongly indicates a successful malolactic acid fermentation. As it has been reported that other strains of L. plantarum can be used as biopreservative agents, the resulting product was also tested in terms of microbial safety after prolonged storage, and by means of metagenome sequencing. The obtained product was quite tolerant to microbial growth, but this observation was rather due to an initial heat treatment than the addition of lactobacilli. Potentially, starter cultures with documented biopreservative activity can be combined with L. plantarum LP58 to obtain a more stable product. Until then, the fermented bilberry juice must be processed and preserved like non-fermented bilberry products. [ABSTRACT FROM AUTHOR]

This study focuses on the impact of new methods for inhibiting malolactic fermentation in white wines on their analytical and sensory properties. Enological preparations with different mechanisms of effect were tested: fumaric acid, chitosan, Estaan (a preparation based on tannin inhibition), medium-chain fatty acids (MCFAs), sulphur dioxide and a control variant. Malolactic fermentation (MLF) was also performed. The samples underwent analysis through HPLC (high-performance liquid chromatography) to determine the concentrations of malic and lactic acid, as well as biogenic amines. GC (gas chromatography) analysis was used to monitor volatile substances, alongside sensory evaluation. This study demonstrated a significant influence of individual enological preparations on the aromatic profile of the examined wines. The SO2 and MCFA variants exhibited the highest concentrations of volatile substances within the esters group, specifically isoamyl acetate, 1-hexyl acetate and phenylethyl acetate. Conversely, the fumaric acid and Estaan variants displayed the lowest concentrations of these esters. The most notable disparities were observed in acetoin concentration, with the MCFA variant exhibiting the lowest values. Additionally, the chitosan variant showed higher concentrations of putrescine and spermidine compared to the MCFA and fumaric acid variants, which presented the lowest levels. [ABSTRACT FROM AUTHOR]

Malolactic fermentation (MLF) in wine is driven by the lactic acid bacterium Oenococcus oeni in most cases. Although this bacterium is resistant to wine stress conditions, it often faces difficulties completing MLF. Previous studies indicate that yeast mannoproteins may improve O. oeni growth and survival in wine. However, very little is known about this topic. This study evaluated the effect of the addition of mannoprotein extracts to culture media on O. oeni growth and its survival to stress conditions and MLF performance. Three commercial mannoprotein extracts were characterized in terms of polysaccharide and protein richness and were used for O. oeni culture media supplementation. The addition of mannoprotein extracts improved the survival of the two evaluated O. oeni strains, PSU-1 and VP41, after acid shock (pH 3.2) in comparison to that of the control. The transcriptional response of four genes involved in mannose metabolism was different depending on the strain, indicating the complexity of sugar metabolism in O. oeni. PSU-1 cells grown with two of the mannoprotein extracts performed faster MLF compared with the control condition, indicating that mannoprotein addition may improve the performance of O. oeni starter cultures, although this effect depends on the strain. [ABSTRACT FROM AUTHOR]

Malolactic fermentation (MLF) is a crucial process to enhance wine quality, and the utilization of indigenous microorganisms has the potential to enhance wine characteristics distinct to a region. Here, the MLF performance of five indigenous Oenococcus oeni strains and six synthetic microbial communities (SynComs), were comparatively evaluated in Cabernet Sauvignon wine. In terms of malate metabolism rate and wine aroma diversity, the strain of O. oeni Oe114–46 demonstrated comparable MLF performance to the commercial strain of O. oeni Oe450 PreAc. Furthermore, the corresponding SynComs (Oe144–46/LpXJ25) exhibited improved fermentation properties, leading to increased viable cell counts of both species, more rapid and thorough MLF, and increased concentrations of important aroma compounds, such as linalool, 4-terpinenol, α-terpineol, diethyl succinate, and ethyl lactate. These findings highlight the remarkable MLF performance of indigenous O. oeni and O. oeni-L. plantarum microbial communities, emphasizing their immense potential in improving MLF efficiency and wine quality.

In wine, lactic acid bacteria (LAB) are responsible for the bioconversion of malic acid to lactic acid, malolactic fermentation that mainly aims at reducing wine acidity. Two LAB strains isolated from the red wine microbiota (Oenococcus oeni 13-7 and Lactobacillus plantarum R1-1), were tested for their ability to exhibit the carbon catabolite repression (CCR) mechanism, that allows the rapid use of certain carbohydrates, over other carbon sources. Bacterial cells were inoculated in 0.1 M glycine buffer (pH 3.5), incubated at 30°C, with different carbohydrates (45 mM) and malic acid (45 mM). For both strains, the presence of glucose significantly inhibited malic acid metabolization (−60%), a similar effect being observed for galactose, mannose and maltose. The highest rate of malic acid conversion was shown in fructose/malate medium. Obtained results showed that malolactic strains can control the utilization of carbon sources via CCR, further studies being necessary to elucidate the mechanisms underlying this process.

Copyright of Food & Fermentation Industries is the property of Food & Fermentation Industries and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This study investigated the synergistic effects of combining Saccharomyces cerevisiae and Oenococcus oeni during the alcoholic fermentation of a low-acidity cider. The initial population of indigenous wild lactic acid bacteria (LAB) in the apple must was 104 CFU/mL. Alcoholic fermentations were carried out without (Cider I) and with (Cider II) the O. oeni inoculation at 105 CFU/mL. As S. cerevisiae grows, a declining trend was observed in indigenous and inoculated LAB populations. While the wild LAB exhibited higher sensitivity than O. oeni, they were not eliminated during alcoholic fermentation. The addition of O. oeni impacted the growth and metabolic activity of S. cerevisiae. The bioconversion of malic acid into lactic acid predominantly occurred during the growth phase (43–66%) and stationary phase (4–27%). The resurgence of O. oeni following alcoholic fermentation significantly impacted the production of volatile compounds. After 20 days of fermentation, Cider II displayed a twofold increase in these compounds, resulting in a more favorable sensory profile according to evaluators. Consequently, malolactic fermentation (MLF) coincided with alcoholic fermentation, leading to a reduction in malic acid content. Furthermore, post alcoholic fermentation, MLF positively enhanced the aromatic quality of low-acid cider made from apples with low acidity. [ABSTRACT FROM AUTHOR]

Copyright of Food Research & Development is the property of Food Research & Development Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Traditional sparkling wines are produced in a two-step sequence of alcoholic fermentations, followed by extended aging which is an influential factor for the final aroma profile. Traditionally, the second fermentation and aging are conducted in bottles over a minimum of 18 months, resulting in an aroma profile which is shaped by oxidative secondary metabolites like aldehydes, acids and fatty acid esters. In this study, a total of 29 traditional commercial sparkling wines from the categories Champagne, Cava, California Champagne, and others (Prosecco and Cremant) were analyzed. The objective was to determine the impact of microbial activity on the stylistic characteristics of traditional sparkling wines and allow winemakers to reproduce the specific fermentation conditions. The results indicate that malolactic fermentation plays an important role in Champagne and some Cavas, but not in the other sparkling wine categories. The metabolic activity of lactic acid bacteria results in an altered acid profile, amino acid utilization, and aroma production. While primary fermentation esters like phenylethyl acetate and isoamyl acetate are significantly reduced in Champagne and Cava, aroma compounds from secondary microbial activity like ethyl lactate and 2-acetyl-1-pyrroline are increased. This underlines the importance of diverse microbial activity of the characteristic style of traditional sparkling wines.

The spontaneous malolactic fermentation (MLF) in a centenary winery from Patagonia, Argentina, is conducted by predominantly mesophilic Oenococcus oeni and Lactiplantibacillus plantarum. In this region, MLF takes place from 14 to 4 °C, leading to heat cellars incurring in higher costs and non-sustainable practices. Previously, psychrotrophic strains of O. oeni had been obtained from a Patagonian wine. The goal of this work was to identify the Lactobacillaceae microbiota related to low-temperature MLF and assess their contribution. Nine sychrotrophicc Lentilactibacillus hilgardii strains were identified by sequencing the 16S rRNA gene, and the strains typified by RAPD-PCR. All strains consumed L-malic acid at 4 and 10 °C in sterile wine. The selected UNQLh1.1 strain revealed implantation capacity and L-malic acid consumption at 4 and 10 °C in the presence of the native microbial consortium. Furthermore, the histidine decarboxylase (hdc) gene was not detected in any of the Len. hilgardii strains. The prevalence of Len. hilgardii under low-temperature conditions represents a novelty compared to previous findings of LAB diversity in the MLF of Patagonian wines. The native Patagonian psychrotrophic Len. hilgardii strains are a new player in fermentations conducted at low temperatures with the potential to be used as a sustainable MLF starter. [ABSTRACT FROM AUTHOR]

The objective was to isolate lactic acid bacteria (LAB) from southern Brazil's wines and investigate their potential as starter cultures for malolactic fermentation (MLF) in Merlot (ME) and Cabernet Sauvignon (CS) wines through the fermentative capacity. The LAB were isolated from CS, ME, and Pinot Noir (PN) wines in the 2016 and 2017 harvests and evaluated for morphological (color and shape of the colonies), genetic, fermentative (increase in pH, acidity reduction, preservation of anthocyanins, decarboxylation of L-malic acid, yield of L-lactic acid, and content of reduced sugars), and sensory characteristics. Four strains were identified as Oenococcus oeni [CS(16)3B1, ME(16)1A1, ME(17)26, and PN(17)65], one as Lactiplantibacillus plantarum [PN(17)75], and one as Paucilactobacillus suebicus [CS(17)5]. Isolates were evaluated in the MLF and compared to a commercial strain (O. oeni), as well as a control (without inoculation and spontaneous MLF), and standard (without MLF). CS(16)3B1 and ME(17)26 isolates finished the MLF for CS and ME wines, respectively, after 35 days, similar to the commercial strain, and CS(17)5 and ME(16)1A1 isolates ended the MLF in 45 days. In the sensory analysis, ME wines with isolated strains received better scores for flavor and overall quality than the control. Compared to the commercial strain, CS(16)3B1 isolate obtained the highest scores for buttery flavor and taste persistence. CS(17)5 isolate received the higher scores for a fruity flavor and overall quality and the lowest for a buttery flavor. The native LAB displayed MLF potential, regardless of the year and grape species from which they were isolated. [ABSTRACT FROM AUTHOR]

Copyright of China Brewing is the property of China Brewing Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The present study was conducted in order to investigate the effects of adding different concentrations of glutathione-enriched inactive dry yeast (g-IDY) at different stages of brewing on the quality of pear wine. Wine was prepared from Korla fragrant pears. g-IDY was added at 10, 20 and 30 mg/L before alcoholic fermentation, malolactic fermentation or aging. After aging for two months, the contents of total and individual phenols, antioxidant activity, organic acid contents, aroma components and sensory evaluation of pear wine were analyzed. The results showed that adding g-IDY before alcoholic fermentation or aging significantly increased the content of total phenols and antioxidant capacity and decreased the color index of pear wine (P < 0.05). Besides, adding g-IDY increased the contents of malic acid, lactic acid and citric acid as well as total the content of flavor substances in pear wine. Adding g-IDY before alcohol fermentation or aging was beneficial to the formation of aromatic compounds and contributed to reducing the generation of some undesirable gas, but it led to the generation of more H2S. Together, these findings showed that pear wine prepared with the addition of 20 mg/L of g-IDY before alcoholic fermentation showed the best quality, with total phenol content of 282 mg/L, total flavor substance content of 13 453.22 mg/L and sensory evaluation score of 88.7 out of 100 points.

This study focuses on the impact of new methods for inhibiting malolactic fermentation in white wines on their analytical and sensory properties. Enological preparations with different mechanisms of effect were tested: fumaric acid, chitosan, Estaan (a preparation based on tannin inhibition), medium-chain fatty acids (MCFAs), sulphur dioxide and a control variant. Malolactic fermentation (MLF) was also performed. The samples underwent analysis through HPLC (high-performance liquid chromatography) to determine the concentrations of malic and lactic acid, as well as biogenic amines. GC (gas chromatography) analysis was used to monitor volatile substances, alongside sensory evaluation. This study demonstrated a significant influence of individual enological preparations on the aromatic profile of the examined wines. The SO2 and MCFA variants exhibited the highest concentrations of volatile substances within the esters group, specifically isoamyl acetate, 1-hexyl acetate and phenylethyl acetate. Conversely, the fumaric acid and Estaan variants displayed the lowest concentrations of these esters. The most notable disparities were observed in acetoin concentration, with the MCFA variant exhibiting the lowest values. Additionally, the chitosan variant showed higher concentrations of putrescine and spermidine compared to the MCFA and fumaric acid variants, which presented the lowest levels.

Malolactic fermentation (MLF) in wine is driven by the lactic acid bacterium Oenococcus oeni in most cases. Although this bacterium is resistant to wine stress conditions, it often faces difficulties completing MLF. Previous studies indicate that yeast mannoproteins may improve O. oeni growth and survival in wine. However, very little is known about this topic. This study evaluated the effect of the addition of mannoprotein extracts to culture media on O. oeni growth and its survival to stress conditions and MLF performance. Three commercial mannoprotein extracts were characterized in terms of polysaccharide and protein richness and were used for O. oeni culture media supplementation. The addition of mannoprotein extracts improved the survival of the two evaluated O. oeni strains, PSU-1 and VP41, after acid shock (pH 3.2) in comparison to that of the control. The transcriptional response of four genes involved in mannose metabolism was different depending on the strain, indicating the complexity of sugar metabolism in O. oeni. PSU-1 cells grown with two of the mannoprotein extracts performed faster MLF compared with the control condition, indicating that mannoprotein addition may improve the performance of O. oeni starter cultures, although this effect depends on the strain.

The present study evaluated the effect of winemaking technologies on the concentration of different biogenic amines in Chardonnay wines. Wines produced from sedimented, inoculated must with active dry yeast without malolactic fermentation were compared with wine produced from nonsedimented must spontaneously fermented with malolactic fermentation. Histamine and putrescine concentrations were not significantly different in either variant. The highest concentration of histamine was 0.055 mg L−1, and the highest concentration of putrescine was 1.6 mg L−1 in both variants. Statistically significantly higher values of cadaverine (from 0.06 to 0.07 mg L−1), spermidine (from 0.8 to 1.4 mg L−1), spermine (from 0.15 to 0.25 mg L−1), and isoamylamine (from 0.40 to 0.46 mg L−1) were found in the variant made from nonsedimented must, in which spontaneous malolactic fermentation was performed. The higher concentration of biogenic amines in this variant may be due to the different composition of lactic bacteria during the spontaneous malolactic fermentation. A simplified, unpublished HILIC method of chromatographic separation of biogenic amines without prior deprivation with MS-MS detection was used to determine individual biogenic amines. [ABSTRACT FROM AUTHOR]

Copyright of Shipin Kexue/ Food Science is the property of Food Science Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Malolactic fermentation (MLF) positively influences the quality of the wine, and it occurs as a result of a lactic acid bacteria's metabolism, mainly of the Oenococcus oeni species. However, delays and halting of MLF are frequent problems in the wine industry. This is mainly because O. oeni's development is inhibited by different kinds of stress. Even though the sequencing of the genome of the PSU-1 strain of O. oeni, as well as other strains, has made it possible to identify genes involved in the resistance to some types of stress, all of the factors that could be involved are still unknown. With the aim of contributing to this knowledge, the random mutagenesis technique was used in this study as a strategy for genetic improvement of strains of the O. oeni species. The technique proved to be capable of generating a different and improved strain when compared to the PSU-1 strain (the parent from which it descends). Then, we evaluated the metabolic behavior of both strains in three different wines. We used synthetic MaxOeno wine (pH 3.5; 15% v/v ethanol), red wine (Cabernet Sauvignon), and white wine (Chardonnay). Furthermore, we compared the transcriptome of both strains, grown in MaxOeno synthetic wine. The specific growth rate of the E1 strain was on average 39% higher in comparison to the PSU-1 strain. Interestingly, E1 strain showed an overexpression of the OEOE&#951794 gene, which encodes a UspA-like protein, which has been described as promoting growth. We observed that the E1 strain was able to convert, on average, 34% more malic acid into lactate than the PSU-1 strain, regardless of the wine being used. On the other hand, the E1 strain showed a flux rate of fructose-6-phosphate production that was 86% higher than the mannitol production rate, and the internal flux rates increase in the direction of pyruvate production. This coincides with the higher number of OEOE&#951708 gene transcripts observed in the E1 strain grown in MaxOeno. This gene encodes for an enzyme fructokinase (EC 2.7.1.4) involved in the transformation of fructose to fructose-6-phosphate. [ABSTRACT FROM AUTHOR]

Fumaric acid (FH2) is an additive allowed by the Codex Alimentarius and the International Organization of Vine and Wine (OIV) that can be used for wine acidification but also to inhibit malolactic fermentation (MLF). FH2 has a positive effect in the reduction in SO2 doses by controlling LAB and other bacteria and by preserving molecular SO2 due to pH effect. This article reports the use of FH2 at 600 mg/L in wines produced with 3 varieties of Vitis vinifera L. grapes (Tempranillo, Garnacha and Viura) made in vintages 2018, 2020 and 2021. Wines treated with 600 mg/L of FH2 were more stable in the long term and showed lower pH by the preservation of malic acid due to both the absence of MLF (which reduced the pH in 0.1–0.2 units compared with controls) and the effect of FH2 acidification (what produced and additional reduction of 0.05–0.1 pH units). The wines treated with FH2 also remained with very low volatile acidity contents close to 0.2 mg/L or lower. These results corroborate that FH2 can be used to successfully control malolactic fermentation in all still wine types (red, white, and rose) from either of the studied varieties. [ABSTRACT FROM AUTHOR]

The study examined the effect of Lactobacillus plantarum together with Saccharomyces cerevisiae on cider quality through simultaneous and sequential inoculation strategies to evoke malolactic fermentation. The antioxidant activities and flavor compound profiles of apple ciders fermented with mixed cultures of commercial wine yeast (S. cerevisia SY) and autochthonous bacteria (L. plantarum SCFF107 and L. plantarum SCFF200) were assessed. The antioxidant ability results indicated that apple ciders fermented with the simultaneous inoculation method had a higher DPPH radical scavenging rate and total antioxidant capacity, especially for SIL107 cider (simultaneous inoculation with S. cerevisiae SY and L. plantarum SCFF107), which exhibited the highest DPPH free radical scavenging activity (78.14% ± 0.78%) and the highest total antioxidant ability (255.92 ± 7.68 mmol/L). The results showed that ciders produced by mixed inoculation with L. plantarum improved flavor because of their higher contents of volatiles such as esters and higher alcohols and higher contents of non-volatile compounds like organic acids and polyphenols in comparison with the single culture of S. cerevisiae, especially for the simultaneous inoculation method. In addition, irrespective of the inoculation mode, compared to the single culture of cider, L-malic acid degraded dramatically in the presence of L. plantarum during alcoholic fermentation, accompanied by increases in lactic acid. What is more, sensory evaluation results demonstrated that ciders produced by mixed cultures gained higher scores than ciders fermented by the single culture of S. cerevisiae, especially in the simultaneous inoculation mode, in terms of the floral, fruity, and overall acceptability of the cider. Therefore, our results indicated that simultaneous inoculation with L. plantarum was found to compensate for some enological shortages of single S. cerevisiae fermented ciders, which could be a potential strategy to enhance the quality of cider products. [ABSTRACT FROM AUTHOR]

Stuck or sluggish malolactic fermentation (MLF) can be problematic in stressful wine conditions, particularly white and sparkling base musts/wines. In these cases, knowledge of yeast-bacteria strain compatibility and the amount of sulfur dioxide (SO2) a yeast strain produces are important considerations for successful MLF. Here, laboratory- and pilot-scale co-fermentations in Chardonnay were used to investigate the effect of yeast-derived SO2 on Oenococcus oeni survival. Although yeast-derived SO2 is generally inhibitory, we show that SO2 production (to approximately 65 mg/L) can be uncoupled from O. oeni survival in the early stages of co-fermentation. Bacterial survival in the presence of specific SO2-producing yeast strains was correlated with the early, transient formation of high acetaldehyde concentrations. Oenococcus oeni survival coincided with molecular SO2 concentrations remaining below an extremely low threshold of inhibition, which exponentially increased from approximately 3–6 µg/L in the first three days of co-fermentation. Strain-dependent sensitivity of O. oeni to bound SO2 remains a possibility, although the extent and mechanism of such inhibition by the SO2 adduct during co-fermentation remain unclear. The choice of co-inoculation yeast strain also influenced wine diacetyl concentration, which was only detected in wines co-inoculated with high SO2-producing S. cerevisiae strains. The wines with high diacetyl concentrations were found to be distinct by a sensory panel, with comparatively high citation frequency for a buttery sensory attribute. Both the SO2- and acetaldehyde production capacity of yeasts are, therefore, seen as meaningful co-inoculation selection criteria. The range of yeast strains suitable for MLF induction by co-inoculation could be widened to include SO2-producing strains that transiently produce an early, high concentration of acetaldehyde. The effects of low, equilibrium concentrations of molecular SO2 should also be considered in conjunction with total SO2 as a measure of SO2 toxicity towards O. oeni following co-inoculation.

This study aimed to investigate the impact of the malolactic fermentation (MLF) carried out by Oenococcus oeni on antihypertensive and antioxidant activities in cider. The MLF was induced using three strains of O. oeni. The modification in phenolic compounds (PCs) and nitrogen organic compounds, antioxidant, and antihypertensive activities were determined after MLF. Among the 17 PCs analyzed caffeic acid was the most abundant compound and phloretin, (−)-epicatechin, and myricetin were detected only in malolactic ciders, however, (−)-epigallocatechin was not detected after MLF. The evaluation of nitrogen organic compounds revealed a drop in total protein concentration (from 17.58 to 14.00 mg N/L) concomitantly with a significant release of peptide nitrogen (from 0.31 to a maximum value of 0.80 mg N/L) after MLF. In addition, an extracellular proteolytic activity was evidenced in all MLF supernatants. The FRAP activity increased reaching a maximum of 120.9 μmol FeSO4/mL and the ABTS radical-scavenging activity increased until 6.8 mmol ascorbic acid/L. Moreover, the angiotensin I-converting enzyme inhibitory activity reached a maximum value of 39.8%. The MLF conducted by O. oeni in ciders enables the increase of interesting biological activities and this finding could constitute a valuable tool to add value to final product.

This study investigated the synergistic effects of combining Saccharomyces cerevisiae and Oenococcus oeni during the alcoholic fermentation of a low-acidity cider. The initial population of indigenous wild lactic acid bacteria (LAB) in the apple must was 104 CFU/mL. Alcoholic fermentations were carried out without (Cider I) and with (Cider II) the O. oeni inoculation at 105 CFU/mL. As S. cerevisiae grows, a declining trend was observed in indigenous and inoculated LAB populations. While the wild LAB exhibited higher sensitivity than O. oeni, they were not eliminated during alcoholic fermentation. The addition of O. oeni impacted the growth and metabolic activity of S. cerevisiae. The bioconversion of malic acid into lactic acid predominantly occurred during the growth phase (43–66%) and stationary phase (4–27%). The resurgence of O. oeni following alcoholic fermentation significantly impacted the production of volatile compounds. After 20 days of fermentation, Cider II displayed a twofold increase in these compounds, resulting in a more favorable sensory profile according to evaluators. Consequently, malolactic fermentation (MLF) coincided with alcoholic fermentation, leading to a reduction in malic acid content. Furthermore, post alcoholic fermentation, MLF positively enhanced the aromatic quality of low-acid cider made from apples with low acidity.

Malolactic fermentation (MLF) positively influences the quality of the wine, and it occurs as a result of a lactic acid bacteria’s metabolism, mainly of the Oenococcus oeni species. However, delays and halting of MLF are frequent problems in the wine industry. This is mainly because O. oeni’s development is inhibited by different kinds of stress. Even though the sequencing of the genome of the PSU-1 strain of O. oeni, as well as other strains, has made it possible to identify genes involved in the resistance to some types of stress, all of the factors that could be involved are still unknown. With the aim of contributing to this knowledge, the random mutagenesis technique was used in this study as a strategy for genetic improvement of strains of the O. oeni species. The technique proved to be capable of generating a different and improved strain when compared to the PSU-1 strain (the parent from which it descends). Then, we evaluated the metabolic behavior of both strains in three different wines. We used synthetic MaxOeno wine (pH 3.5; 15% v/v ethanol), red wine (Cabernet Sauvignon), and white wine (Chardonnay). Furthermore, we compared the transcriptome of both strains, grown in MaxOeno synthetic wine. The specific growth rate of the E1 strain was on average 39% higher in comparison to the PSU-1 strain. Interestingly, E1 strain showed an overexpression of the OEOE_1794 gene, which encodes a UspA-like protein, which has been described as promoting growth. We observed that the E1 strain was able to convert, on average, 34% more malic acid into lactate than the PSU-1 strain, regardless of the wine being used. On the other hand, the E1 strain showed a flux rate of fructose-6-phosphate production that was 86% higher than the mannitol production rate, and the internal flux rates increase in the direction of pyruvate production. This coincides with the higher number of OEOE_1708 gene transcripts observed in the E1 strain grown in MaxOeno. This gene encodes for an enzyme fructokinase (EC 2.7.1.4) involved in the transformation of fructose to fructose-6-phosphate.

Malolactic fermentation (MLF) is the decarboxylation of L-malic acid to L-lactic acid by lactic acid bacteria (LAB). For the majority of wine production, secondary fermentation is crucial. MLF significantly impacts the quality of most red and some white wine. The outcomes of the spontaneously initiated and finished MLF are frequently unpredictable and can even cause the wine to deteriorate. As a result, individuals typically favour inoculating superior starter cultures when performing MLF. The MLF method for wine has, however, faced new difficulties because of the altered wine fermentation substrate environment brought on by global climate change, the growing demands of winemakers for production efficiency, and the rising demand for high-quality wine. To serve as a reference for the study of wine production and MLF in the current situation, this review primarily updates and summarises the research findings on increasing the effectiveness and dependability of MLF in recent years. [ABSTRACT FROM AUTHOR]

There are two main fermentations associated with the vinification process. Alcoholic fermentation (AF), which is conducted by yeasts and malolactic fermentation (MLF), which takes place as a result of the metabolic activity of lactic acid bacteria (LAB) of the genera Oenococcus, former-Lactobacillus, Pediococcus and Leuconostoc. MLF is defined as the biotransformation of L-malic acid to L-lactic acid and carbon dioxide and in addition to deacidification, contributes significantly to microbial stability and often to the improvement of the sensory profile of wines. Therefore, the abiotic and biotic factors that affect MLF, along with its correlation with quality characteristics, has been in the epicenter of intensive research. In addition, practical issues that accompany MLF have also been considered and adequately assessed. The aim of the present review was to explore and critically discuss MLF from both theoretical and practical perspectives. [ABSTRACT FROM AUTHOR]

Spent coffee grounds (SCG) disposal is an environmental problem. These residues from coffee brewing and instant coffee production have potential to produce novel alcoholic beverages. SCG valorization through sequential alcoholic and malolactic fermentation was investigated using a yeast, Lachancea thermotolerans Concerto and a lactic acid bacterium (LAB), Oenococcus oeni Lalvin 31 in this study. Our results showed that sequential inoculation prevented early death of yeast confronted when simultaneous inoculation was adopted, allowing for growth and persistence of both yeast and LAB till the end of fermentation. Adequate ethanol production (4.91 ± 0.13 %, v/v) with low residual sugar content was also attained. In addition, relatively lower levels of acetic, lactic, and succinic acids were produced by sequential inoculation than that of simultaneous inoculation. Furthermore, SCG hydrolysates fermented via sequential inoculation had the widest variety of volatiles (e.g. esters and ketones). Overall, our results indicated that sequential inoculation of L. thermotolerans and O. oeni in SCG hydrolysates might be a way to develop novel beverages with pleasant flavor profiles.

To investigate the effects of inoculating with three strains of lactic acid bacteria on prune wine quality during malolactic fermentation, this study determined its antioxidant activity, phenolic compounds, organic acids, and volatile/non-volatile metabolites. The results showed that inoculation with Lactobacillus paracasei SMN-LBK improved the antioxidant activity and phenolic compounds of prune wine. 73 VOCs were detected in prune wine by HS-SPME-GC–MS, and VOC content increased by 4.3% and 9.1% in MLFS and MLFB, respectively. Lactobacillus delbrueckii subsp. Bulgaricus showed better potential for winemaking, and citral and 5-nonanol, were detected in the MLF samples. 39 shared differential metabolites were screened and their metabolic pathways were investigated based on nontargeted metabolomics. Differences in amino acid and flavonoid content between strains reflected their specificity in flavonoid biosynthesis and amino acid biosynthesis. These findings will provide useful information for the biochemical study and processing of prune wine. • Inoculation different LAB affects the quality of prune wine during MLF. • The type and content of phenolic compounds are related to the LAB species. • MLF produces more unique aroma substances and improves the aroma. • The metabolic pathway of MLF in prune wine was analyzed using metabolomics. • Some of the amino acid metabolic pathways were enhanced in MLFS and MLFB. [ABSTRACT FROM AUTHOR]

[Display omitted] • Application of indigenous O. oeni facilitates quick start-up and completion of the MLF. • Co-inoculation significantly reduced overall winemaking time. • Co-inoculation achieved greater volatile and sensory outcomes of Chardonnay wine. • Six key aroma-active compounds were identified in wine of mixed fermentation. There has been growing interest in the use of mixed cultures comprised of Oenococcus oeni and Saccharomyces cerevisiae to produce wine with local style and typicality. This study has investigated the influence of the inoculation protocol of O. oeni on the fermentation kinetics and aromatic profile of Chardonnay wine. The one selected autochthonous O. oeni strain (ZX-1) inoculated at different stages of the alcoholic fermentation process successfully completed malolactic fermentation (MLF). Co-inoculum of S. cerevisiae and O. oeni enabled simultaneous alcoholic fermentation and MLF, leading to at least a 30 % reduction in the total fermentation time when compared to the sequential inoculation process, which was attributed to the lower ethanol stress. Meanwhile, co-inoculum stimulated the accumulation of volatile aroma compounds in Chardonnay wine. In particular, the mixed modality where the O. oeni strain ZX-1 was inoculated 48 h after S. cerevisiae allowed higher levels of terpenes, acetates, short-chain, and medium-chain fatty acid ethyl esters to be produced, which may result in the enhanced floral and fruity attributes of wine. Aroma reconstitution and omission models analysis revealed that the accumulation of linalool, geraniol, isoamyl acetate, ethyl hexanoate, and ethyl caprylate during the mixed fermentation process enhanced the stone fruit, tropical fruit, and citrus aromas in Chardonnay wine. Therefore, the simultaneous fermentation of S. cerevisiae and autochthonous O. oeni ZX-1 has a positive effect on MLF and contributes to producing wines with distinctive style. [ABSTRACT FROM AUTHOR]

[Display omitted] • Histamine and tyramine are the most toxic biogenic amines found in wine. • Biogenic amines are primarily produced by lactic acid bacteria. • Yeast fermentation and autolysis also contribute to the formation of biogenic amines. • Levels of amines can be reduced by non- Saccharomyces yeasts and degrading bacteria. • Treating with degrading enzymes can decrease the biogenic amines content in wines. Fermented beverages, including wine, can accumulate high concentrations of biogenic amines (BAs), which can pose potential health risks. BAs are produced by various yeasts and lactic acid bacteria (LAB) during winemaking. LAB are the main contributors to the formation of histamine and tyramine, the most toxic and food safety relevant biogenic amines. Numerous factors, ranging from agricultural and oenological practices to sanitation conditions, can contribute to the formation of BAs in wines. Moreover, organic and biodynamic wines impose limitations on the use of common food additives employed to control the proliferation of native and spoilage microorganisms during vinification and storage. To mitigate histamine production, commercial starter cultures incapable of synthesising histamine have been effectively utilised to reduce wine histamine content. Alternative fermentative microorganisms are currently under investigation to enhance the safety, quality, and typicity of wines, including indigenous LAB, non- Saccharomyces yeasts, and BAs degrading strains. Furthermore, exploration of extracts from BAs-degrading microorganisms and their purified enzymes has been undertaken to reduce BAs levels in wines. This review highlights microbial contributors to BAs in wines, factors affecting their growth and BA production, and alternative microorganisms that can degrade or avoid BAs. The aim is to lessen reliance on additives, providing consumers with safer wine choices. [ABSTRACT FROM AUTHOR]

Lingonberry is a common wild berry that is often sold as jams and beverages. It naturally contains high amounts of the weak acid preservative benzoic acid making it an interesting ingredient for shelf-life extension. Despite this, their use as a raw ingredient is limited by the inherently intense sour taste. This study aimed to improve the taste of lingonberry juice by subjecting it to malolactic fermentation in order to reduce the sourness, and to investigate the benzoic acid in lingonberries as a natural preservative in juice blends by determining the microbial stability. After initial screening of lactic acid bacteria, a Lactiplantibacillus plantarum strain was used as the starter for subsequent investigations. Upon raising the pH, all malic acid was completely converted to lactic acid after seven days. The fermented juice was mixed with blackcurrant juice in different proportions. Challenge tests of the blends showed Listeria monocytogenes could not grow in any juice samples, while Candida albicans only grew in the pure blackcurrant juice. Aspergillus brasiliensis growth was delayed in all samples containing benzoic acid in a concentration-dependent manner. The sourness and astringency were substantially reduced in the juice with added L. plantarum compared to the unfermented juice. • Using lactic acid bacteria, malic acid was converted to lactic acid after pH adjustment. • The fermented juice and juice blends were perceived as less sour and astringent than the unfermented juice. • Lingonberry juice has preservative activity that, due to benzoic acid, inhibits or delays growth of spoilage microorganisms. [ABSTRACT FROM AUTHOR]

The spontaneous malolactic fermentation (MLF) in a centenary winery from Patagonia, Argentina, is conducted by predominantly mesophilic Oenococcus oeni and Lactiplantibacillus plantarum. In this region, MLF takes place from 14 to 4 °C, leading to heat cellars incurring in higher costs and non-sustainable practices. Previously, psychrotrophic strains of O. oeni had been obtained from a Patagonian wine. The goal of this work was to identify the Lactobacillaceae microbiota related to low-temperature MLF and assess their contribution. Nine sychrotrophicc Lentilactibacillus hilgardii strains were identified by sequencing the 16S rRNA gene, and the strains typified by RAPD-PCR. All strains consumed L-malic acid at 4 and 10 °C in sterile wine. The selected UNQLh1.1 strain revealed implantation capacity and L-malic acid consumption at 4 and 10 °C in the presence of the native microbial consortium. Furthermore, the histidine decarboxylase (hdc) gene was not detected in any of the Len. hilgardii strains. The prevalence of Len. hilgardii under low-temperature conditions represents a novelty compared to previous findings of LAB diversity in the MLF of Patagonian wines. The native Patagonian psychrotrophic Len. hilgardii strains are a new player in fermentations conducted at low temperatures with the potential to be used as a sustainable MLF starter.

Oenococcus oeni is the main microorganism that undergoes malolactic fermentation (MLF) in the winemaking industry due to its excellent adaptability to harsh wine environments. The start of MLF is often delayed or even fails, and low pH appears to be a crucial parameter. To study the function of the trxA gene in acid stress, a plasmid containing the trxA gene of O. oeni SD-2a was heterologously expressed in Lactiplantibacillus plantarum WCFS1. The recombinant strain (WCFS1-trxA) grew better than the control strain (WCFS1-Vector) under acid stress. The expression of thioredoxin system genes was much higher in the recombinant strain compared with the control strain under acid stress. In addition, a series of physiological and biochemical assays were conducted. The ATP content was lower in the recombinant strain, while the cell membrane fluidity and integrity improved in the recombinant strain. Moreover, reactive oxygen species (ROS) accumulation, intracellular GSH level, and superoxide dismutase (SOD) activity assays showed that the recombinant strain decreased the intracellular reactive oxygen species (ROS) accumulation by improving the SOD activity. In conclusion, heterologous expression of trxA improves the SOD activity of L. plantarum WCFS1, reducing bacterial ROS and increasing cell membrane fluidity and integrity, enhancing the tolerance of Lactiplantibacillus plantarum WCFS1 under acid stress. [ABSTRACT FROM AUTHOR]

Malolactic fermentation (MLF) converts malic acid into lactic acid by lactic acid bacteria (LAB). MLF may affect potential wine quality impact as global warming intensifies, and the alcohol in the wine increases, which threatens MLF. Lactiplantibacillus plantarum is considered a new generation of MLF starter because of the ability of high ethanol tolerance and good enological characteristics. In this research, 132 LAB strains were isolated from the eastern foothills of Helan Mountain in Ningxia, China. Twenty-one higher ethanol tolerance isolates were obtained by 15% (v/v) ethanol preliminary screening. They were identified by 16S rRNA sequencing and differentiated by randomly amplified polymorphic DNA (RAPD). Stress factors include ethanol, pH, and SO2, and the combination of stresses was used to screen stress-tolerance strains. β-D-glucosidase activity, MLF performance, and biogenic amine content were tested to evaluate the enological characteristics. GC-MS detected the volatile components of the wine after MLF. The results showed that twenty strains were identified as L. plantarum, and one strain was Lentilactobacillus hilgardii. Especially, the strains of A7, A18, A23, A50, and B28 showed strong resistance to high ethanol, low pH, and high SO2. A7, A50, and B28 showed better β-D-glucosidase activity and thus were inoculated into cabernet sauvignon wines whose ethanol content was 14.75% (v/v) to proceed MLF. A7 finished MLF in 36 d, while the control strains Oenococcus oeni 31-DH and L. plantarum BV-S2 finished MLF in 24 d and 28 d, respectively. Nevertheless, A50 and B28 did not finish MLF in 36 d. The data showed that A7 brought a more volatile aroma than control. Notably, the esters and terpenes in the wine increased. These results demonstrated the potential applicability of L. plantarum A7 as a new MLF starter culture, especially for high-ethanol wines. [ABSTRACT FROM AUTHOR]

Conventional pear–kiwifruit wine has a bland flavor and sour taste, because of excessive l-malic acid content and, consequently, little consumer appeal. An Oenococcus oeni strain, GF-2, has good malolactic fermentation (MLF) performance and high glucosidase activity. Through a Box–Behnken design, the optimum MLF parameters for deacidification by GF-2 were determined: initial pH of 3.4, 5% v/v inoculation, and temperature of 20 °C, which reduced the malic acid content by 98.3%. The changes in the content of organic acids, polyphenols, and aromatic compounds after MLF were compared with chemical deacidification. MLF significantly decreased the total concentration of organic acids by 29.7% and promoted the accumulation of aromatic esters, higher alcohols, and terpenoids, but chemical deacidification markedly decreased aromatic compound content by 59.8%. MLF wine achieved the highest sensory scores for aroma, taste, and overall acceptability. Therefore, MLF with O. oeni GF-2 has great potential to markedly improve the quality of commercial pear–kiwifruit wine. [ABSTRACT FROM AUTHOR]

Background and Aims: Torulaspora delbrueckii is being used increasingly as a starter for alcoholic fermentation (AF) because of its chemical modulation of wine. Previous studies on this yeast in a natural must have shown a different Oenococcus oeni population by the end of MLF. In this study we aim to evaluate this aspect in a defined O. oeni strain consortium in a sterile grape must during winemaking. Methods and Results: Before commencing AF with either S. cerevisiae or both T. delbrueckii and S. cerevisiae, the must was inoculated with a defined population of O. oeni strains. The use of T. delbrueckii determined the bacterial population at the end of MLF. Also, the inoculation of a selected strain after AF produced wines with different chemical composition to those fermented with the initial bacterial community. Conclusions: Different yeast inoculation strategies modulate the O. oeni population, and this has an impact on the chemical composition of the wines. Moreover, the inoculation of a small O. oeni population in must leads to a process similar to spontaneous MLF. Significance of the Study: Torulaspora delbrueckii can be used as a tool to modulate the O. oeni population and enhance the aromas related to MLF. [ABSTRACT FROM AUTHOR]

The alcoholic beverage industry has grown exponentially in terms of the production of alcohol-containing products in an artisanal manner. Thus, it is proposed to implement an agroindustrial production alternative by making fruit wine from curuba (Passiflora mollissima) using a Saccharomyces Cerevisiae (Var. Bayanus) yeast strain. Three phases were developed; the first consisted of obtaining and fermenting the curuba pulp; the second phase included physicochemical and microbiological characterization, evaluating parameters such as pH, acid-base titration, soluble solids, color, viscosity, yeast count by deep seeding on YGC agar and LAB count on MRS agar to verify malolactic fermentation; finally, sensory analysis was performed through a quantitative descriptive analysis (QDA) in solitary and paired. The result obtained was a beverage with a pH of 3,14±0,02, a viscosity of 2,31±0,02 cP, soluble solids content of 7,65±0,07 °Brix and an alcohol content of 12,91±0,19 v/v. Thus, the study demonstrates that curuba has a high biotechnological potential in the elaboration of fermented beverages, offering an additional alterna- tive for the elaboration and commercialization of new products in the department of Huila (Colombia). [ABSTRACT FROM AUTHOR]

Malolactic fermentation (MLF) is a challenging and time-consuming step in the winemaking process. The effects of climate change are making the intrinsic conditions in red wine more challenging for the growth of lactic acid bacteria through interfering with a prompt and effective MLF. However, this is a necessary process in red wine production that contributes to high quality of wine demanded by consumers. Previous studies in our group reported a highly efficient MLF of red wine by using encapsulated Oenococcus oeni. Here, we designed a bench-scale packed-bed reactor using encapsulated bacteria to facilitate and speed up this process. The time to complete MLF was reduced as the concentration of biocapsules increased. The system exhibited operational stability and efficiency in sequential batches of wine recirculated through the column. Furthermore, an efficient continuous MLF was achieved using the packed-bed reactor. In general, a slight reduction in the concentration of some volatile organic compounds (VOCs) in the wines from the continuous system was observed as compared to those from the recirculated system. [ABSTRACT FROM AUTHOR]

This research concluded in getting experimental data about the composition of organic acids in wines obtained from varieties Cabernet-Sauvignon, Merlot, Pinot Noir, Rara Neagra, Feteasca Neagra, Shiraz (Syrah) produced within C.V. ”Cricova” S.A between 2015–2019 years. Also, it was argued the need to apply the malolactic fermentation simultaneously with alcoholic fermentation in order to increase the quality of young dry red wines, which allows the launch of the finished product in a restricted period of time. The degradation of malic acid in wine was achieved by malolactic fermentation bacteria, removing the excessive fresh taste of young wines ”Primeur” and ”Virgin”.

As a consequence of the alcoholic fermentation carried out by yeasts in wine, several compounds can be delivered to the medium, promoting or inhibiting the malolactic fermentation (MLF) and the lactic acid bacteria, mainly Oenococcus oeni. Succinic acid is one of these compounds and is an example of the interaction between yeasts, including non-Saccharomyces species, and O. oeni. However, the influence of succinic acid on the MLF has been researched very little as yet. In this work, we study the influence of succinic acid and pH on O. oeni CH11 and PSU-1 strains, both during MLF and in resting cell experiments. Moreover, we analysed the relative expression of some significant genes related to stress and malolactic activity to determine how the O. oeni strains were affected by the succinic acid. The results showed that the succinic acid could act as an MLF inhibitor at concentrations higher than 1 g/L, but it can be beneficial at 0.5 g/L. This variable effect also depends on the strains and other winemaking conditions, mainly pH, which influences the dissociated and undissociated forms of both acids. The inhibiting effect of succinic seems clearer when it is at a molar concentration higher than that of L-malic acid. Experiments with resting cells have confirmed that O. oeni consumes less L-malic acid when succinic acid is higher than 1 g/L. Genetic expression experiments showed that in the presence of succinic acid (2 g/L), gene hsp18 encoding stress protein was up-regulated in strain CH11, suggesting a good response and adaptation of this strain to stress. On the other hand, genes mleA and mleP, which are related to malolactic activity, were not affected by succinic acid, except for strain PSU-1 at pH 4.0. Further research is necessary to understand better the effects of succinic acid on O. oeni and MLF.

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Lactic acid bacteria are very important in winemaking. In this study, 108 lactic acid bacteria isolates were obtained from high-ethanol-content (~17% (v/v)) Grenache wines during uninoculated malolactic fermentation (MLF). The 16S rRNA and species-specific PCR showed that 104 of these were Oenococcusoeni, three were Lactobacillus hilgardii, and one was Staphylococcus pasteuri. AFLP of HindIII and MseI digests of the genomic DNA of the O. oeni strains was developed for the first time to discriminate the strains. The results showed that the method was a suitable technique for discriminating the O. oeni strains. Based on the cluster analysis, nine O. oeni strains were chosen for inclusion in an ethanol tolerance assay involving monitoring of optical density (ABS600nm) and viable plating. Several O. oeni strains (G63, G46, G71, G39) survived and grew well in MRS-AJ with 17% (v/v) ethanol, while the commercial O. oeni reference strain did not. Strain G63 could also survive and grow for 168 h after inoculation in MRS-AJ medium with 19% (v/v) ethanol. These results suggest that O. oeni G63, G46, G71, and G39 could potentially be used as MLF starters for high-ethanol-content wines. All three L. hilgardii strains could survive and grow in MRS-AJ with 19% (v/v) ethanol, perhaps also indicating their suitability as next-generation MLF starter cultures. [ABSTRACT FROM AUTHOR]