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The winemaking process includes two main steps: lactic acid bacteria are responsible for the malolactic fermentation which follows the alcoholic fermentation by yeasts. Both types of microorganisms are present on grapes and on cellar equipment. Yeasts are better adapted to growth in grape must than lactic acid bacteria, so the alcoholic fermentatio...
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... sugars together with malic acid. The malolactic fermentation may be more or less finished, while there may still be some unfermented sugar. Normally the interactions between yeasts and bacteria, together with the effect of sulfur dioxide added to grape must, prevent such premature bacterial growth. The volatile acidity resulting from a ‘piqûre lactique’ can be ascribed to lactic acid bacteria by determination of D-lactic acid, which is the only stereoisomer formed, besides acetic acid, by the dominant heterofermentative cocci. This major incident of winemaking is not rare. The technological operations and monitoring of alcoholic fermentation must be strict. Difficulties are predictable when grapes are very mature, particularly when the climate is hot and dry before harvest. In these conditions, the high sugar and low acidity of must are both factors which are respectively in favor of stuck in yeast activity and of bacteria growth. Fortified wines are also affected by ‘piqûre lactique’. These products are prepared by the addition of brandies or wine spirits (Cognac, Armagnac) to grape must more or less fermented by yeast. They have a 16 to 20% ethanol level and contain variable but rather high concentrations of hexoses. Port, Sherry, Pinaud des Charentes are some examples. In spite of their high level in ethanol, the heterofermentative lactobacilli can multiply. Since the generation time of bacteria in such an environment is long, the multiplication becomes evident most often during barrel aging or after bottling. Volatile acidity is unaccept- able, and the wine is gaseous and cloudy. Most of the time L. hilgardii and L. fructivorans strains are involved. Some strains are not only tolerant to ethanol, but also dependent on ethanol for growth (Couto & Hogg 1994). The other spoilages of taste and aromas may be attributed to the development of special lactic acid bacteria strains instead of species. In 1860 Pasteur described three ‘wine diseases’ named ‘amertume’, ‘tourne’ and ‘graisse’. The microorganisms responsible for these alterations were lactic acid bacteria. The first two diseases are not widespread in wines, and they result from the glycerol and tartaric acid metabolism by lactobacilli. The third is more usual and a real concern for many wines of the 1997 vintage. This deterioration is characterized by an abnormal increase in viscosity, to such an extent that the wine runs thicker than oil. The ropy wines contain polysaccharides produced from residual sugars (less than 1 g/l) by strains of Pediococcus damnosus . This species is normally present in grape must and disappears almost completely during the winemaking process. Sometimes P. damnosus also plays a large part in malolactic fermentation. Most of the P. damnosus strains are not spoilage agents. Only some of them can synthetize exocellular polysaccharides (EPS). The glucan produced from glucose has a trisaccharides repeating unit structure (Llauberes et al. 1990) (Figure 4). Concentrations of the glucan around 100 mg/l are high enough to give the wine the abnormal and unac- ceptable viscosity. P. damnosus strains which produce the EPS differ from ordinary strains by the presence of a 4 kb plasmid. During repeated transfers of ropy P. damnosus strains in culture media added with both 8 to 11% ethanol, the ropy character is conserved and the plasmid is stable. The ropy strains are much more tolerant to ethanol than the others. The loss of the plasmid by repeated subcultures in laboratory broth is correlated to the loss of the ability to produce the EPS. Thus, although it has not been verified that the transformation of unropy strains by the plasmid could transfer the EPS synthesis ability, several observations support the hypothesis that it is really involved in the phenomenon. A DNA probe obtained by labelling a 1.2 kb part of the plasmid is routinely used to detect the presence of such strains in wine (Lonvaud-Funel et al. 1993). The function encoded by the plasmid is unknown. The deterioration may occur when wine is still in vats. In this case, it is possible to recover a normal viscosity by mechanical treatments. Generally the wine does not have other defaults except if other microorganisms, yeast or bacteria are also present. However, in most cases, the ropiness develops very slowly and becomes evident several weeks or months after bottling. Knowledge on these particular strains is not yet sufficient to understand their behaviour in wine, their possible relations with other microorganisms and the factors involved in EPS synthesis, in order to predict their development. In consequence, today the detection of such bacteria in wine before bottling requires treatment with very drastic filtration steps or by heating. In addition as they are very tolerant to hostile conditions and even to SO 2 (perhaps because of the EPS layer around the cell), the contamination of a whole cellar is very easy. Rigorous cleaning of all the equipment is the only means to eliminate ...
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... In the context of wine production, wine lees represent a potentially interesting source of nutrients and protective compounds for the lactic acid bacteria (LAB) which are used to perform the malolactic fermentation (MLF). Oenococcus oeni and to a lesser extent Lactiplantibacillus plantarum are the main LAB species driving MLF (Lonvaud-Funel, 1999). Most often they develop spontaneously in wine during or after AF and perform MLF when they reach a sufficient population. ...
... However, MLF can lead to undesirable effects, such as excessive de-acidification, which can result in microbial spoilage [2], the formation of undesirable toxic molecules like biogenic amines or ethyl carbamate [3] and reduced colour intensity (up to 30% in some cases) and stability [4]. ...
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.
... Lactic acid bacteria (LAB) and yeasts are instrumental in this context. LAB catalyze the conversion of dicarboxylic malic acid into monocarboxylic lactic acid and carbon dioxide (malolactic fermentation MLF) and yeasts convert sugars into alcohol (alcoholic fermentation) [44]. During malolactic fermentation by LAB, no free intermediary products are formed, achieving a more palatable wine by reducing the tart taste of malic acid. ...
Many bacteria have the ability to survive in challenging environments; however, they cannot all grow on standard culture media, a phenomenon known as the viable but non-culturable (VBNC) state. Bacteria commonly enter the VBNC state under nutrient-poor environments or under stressful conditions. This review explores the concept of the VBNC state, providing insights into the beneficial bacteria known to employ this strategy. The investigation covers different chemical and physical factors that can induce the latency state, cell features, and gene expression observed in cells in the VBNC state. The review also covers the significance and applications of beneficial bacteria, methods of evaluating bacterial viability, the ability of bacteria to persist in environments associated with higher organisms, and the factors that facilitate the return to the culturable state. Knowledge about beneficial bacteria capable of entering the VBNC state remains limited; however, beneficial bacteria in this state could face adverse environmental conditions and return to a culturable state when the conditions become suitable and continue to exert their beneficial effects. Likewise, this unique feature positions them as potential candidates for healthcare applications, such as the use of probiotic bacteria to enhance human health, applications in industrial microbiology for the production of prebiotics and functional foods, and in the beer and wine industry. Moreover, their use in formulations to increase crop yields and for bacterial bioremediation offers an alternative pathway to harness their beneficial attributes.
... However, MLF can lead to undesirable effects, such as excessive de-acidification, which can result in microbial spoilage [2], the formation of undesirable toxic molecules like biogenic amines or ethyl carbamate [3], and reduced colour intensity (up to 30% in some cases) and stability [4]. ...
The 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 mecha-nisms of effect were tested: fumaric acid, chitosan, Estaan (a preparation based on tannin inhibi-tion), medium-chain fatty acids (MCFA), sulphur dioxide and a control variant where malolactic fermentation (MLF) was performed. The samples underwent analysis through HPLC (high-performance liquid chromatography) to determine concentrations of malic and lactic acid, as well as biogenic amines. GC (gas chromatography) analysis was used to monitor volatile sub-stances, alongside sensory evaluation. The study demonstrated a significant influence of indi-vidual 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, spe-cifically 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.
... Lactic acid bacteria (LAB) and yeast are instrumental in this context. LAB catalyze the conversion of dicarboxylic malic acid into monocarboxylic lactic acid and carbon dioxide (malolactic fermentation MLF) and yeast convert sugars into alcohol (alcoholic fermentation) [55]. During malolactic fermentation by LAB, no free intermediary products are formed achieving a more palatable wine by reducing the tart taste of malic acid. ...
Many bacteria have the ability to survive in challenging environments; however, they cannot grow on standard culture media, a phenomenon known as the Viable but Non-Culturable (VBNC) state. Bacteria commonly go into the VBNC state under nutrient-poor environments or under stressful conditions. This review explores the concept of the VBNC state, providing insights into the beneficial bacteria known to employ this strategy. The investigation covers different chemical and physical factors that can induce the latency state, cell features, and gene expression observed in cells in the VBNC state. The revision also covered the significance and applications of beneficial bacteria, methods for evaluating bacterial viability, the ability of bacteria to persist in environments associated with higher organisms, and the factors that facilitate the return to the culturable state. Knowledge about beneficial bacteria capable of entering the VBNC state remains limited, however, beneficial bacteria in this state could face adverse environmental conditions, and return to culturable state when conditions become suitable and continue to exert their beneficial effects. Likewise, this unique feature positions them as potential candidates for healthcare applications, such as the use of probiotic bacteria to enhance human health, applications in industrial microbiology for the production of prebiotics, functional foods, and in the beer and wine industry. Moreover, their use in formulations to increase crop yield and for bacterial bioremediation offers an alternative pathway to harness their beneficial attributes.
... First, AF transforms fructose and glucose of grape juice mainly into ethanol and CO 2 . Then MLF, in the late stage of AF, transforms malic acid into lactic acid to ensure deacidification, microbial stabilization and improved final quality for many red wines and some white wines (Bauer and Dicks, 2004;Lonvaud-Funel, 1999). ...
... Thus, the most common method used to trigger MLF is the inoculation of selected malolactic bacteria (Coucheney et al., 2005;Lasik, 2013). Oenococcus oeni is the most commonly used LAB strain in wine, especially in acid wines (Lonvaud-Funel, 1999;Van Vuuren and Dicks, 1993). In fact, O. oeni is well-adapted to the harsh conditions imposed by the wine matrix due to efficient intracellular pH regulation mechanism, the adjustment of membrane stability (Grandvalet et al., 2008;Maitre et al., 2014), the synthesis of stress proteins, especially sHsp Lo18 (Beltramo et al., 2006;Coucheney et al., 2005;Guzzo et al., 2000;Jobin et al., 1997), and biofilm formation (Bastard et al., 2016). ...
... Especially, the species T. delbrueckii has shown positive impacts enhancing the efficiency and effectiveness of the process (Balmaseda et al., 2021a(Balmaseda et al., , 2022Ferrando et al., 2020). MLF has a great impact on wine characteristics, mainly in overall acidity but also in flavour and aroma, due to the decarboxylation of L-malic acid into Llactic acid by lactic acid bacteria (LAB), with Oenococcus oeni being the main bacteria responsible for this process in winemaking (Arnink and Henick-Kling, 2005;Lonvaud-Funel, 1999). ...
Progress in oenological biotechnology now makes it possible to control alcoholic (AF) and malolactic (MLF) fermentation processes for the production of wines. Key factors in controlling these processes and enhancing wine quality include the use of selected strains of non-Saccharomyces species, Saccharomyces cerevisiae, and Oenococcus oeni, as well as the method of inoculation (co-inoculation or sequential) and the timing of inoculation. In the present work, we investigated the effects of different inoculation strategies of two Torulaspora delbrueckii (Td-V and Td-P) strains followed by S. cerevisiae. Times (two, four, and six days) and types (co-inoculation and sequential) of inoculation were evaluated on the AF of a synthetic grape must. Furthermore, this synthetic medium was optimized by adding linoleic acid and β-sitosterol to simulate the natural grape must and facilitate reproducible results in potential assays. Subsequently, the wines obtained were inoculated with two strains of Oenococcus oeni to carry out MLF. Parameters after AF were analysed to observe the impact of wine composition on the MLF performance. The results showed that the optimization of the must through the addition of linoleic acid and β-sitosterol significantly enhanced MLF performance. This suggests that these lipids can positively impact the metabolism of O. oeni, leading to improved MLF efficiency. Furthermore, we observed that a 4-day contact period with T. delbrueckii leads to the most efficient MLF process and contributed to the modification of certain AF metabolites, such as the reduction of ethanol and acetic acid, as well as an increase in available nitrogen. The combination of Td-P with Oo-VP41 for 4 or 6 days during MLF showed that it could be the optimal option in terms of efficiency. By evaluating different T. delbrueckii inoculation strategies, optimizing the synthetic medium and studying the effects on wine composition, we aimed to gain insights into the relationship between AF conditions and subsequent MLF performance. Through this study, we aim to provide valuable insights for winemakers and researchers in the field of wine production and will contribute to a better understanding of the complex interactions between these species in the fermentation process.
... This process, in which malic acid is transformed into lactic acid and carbon dioxide, usually takes place after alcoholic fermentation and is particularly desirable for red wines. Among the main lactic acid bacteria found in wines are: Lactobacillus brevis, Lactobacillus higardii, Leuconostoc mesenteroides, Oenococcus oeni, Lactobacillus casei, Lactobacillus plantarum, Pediococcus damnosus and Pediococcus pentosaceus [6]. Although malolactic fermentation is mainly produced by Oenococcus oeni, many of these bacteria are present during vinification and can be disruptive. ...
... hilgardii, P. parvulus) or ethyl carbamate (L. brevis, L. buchneri) [6]. ...
... Acetic acid bacteria are strictly aerobic, Gram-negative, non-sporulating, ellipsoidal, or round in shape. They are ubiquitous in nature and obtain energy mainly by the oxidation of sugars and ethanol to acetic acid [6]. In addition to the presence of O 2 , their growth can be influenced by other factors like pH and temperature. ...
Carbonic maceration (CM) vinification is a very traditional method that allows saving energy without great equipment investment, obtaining high-quality wines. However, due to its particularities, CM winemaking implies a higher risk of microbial alteration. This work studies the evolution of bacterial population along carbonic maceration wines elaboration with and without yeast inoculation. In the same way, two strategies of yeast inoculation were studied: “pied de cuve” and Active Dry Yeasts (ADY) seed. For this purpose, three conditions were assayed: spontaneous fermentation (without inoculation), “pied de cuve” technology, and ADY inoculation. For each condition, two winemaking methods were compared: carbonic maceration and the standard method of destemming and crushing (DC). The bacterial evolution (lactic acid and acetic acid bacteria) was followed in different fermentation stages. Finally, the wines obtained were analysed (pH and volatile acidity). In the non-inoculated wines produced by CM, high development of the bacterial population was observed (counts of acetic acid bacteria around 4.3 log cfu/mL), and finished wines presented high values of volatile acidity (>1.5 g/L), which did not occur in the inoculated vinifications (counts of acetic acid bacteria around 1.5 log cfu/mL and 0.5 g/l of volatile acidity). Thus, the control of yeast population, as a “pied de cuve” as ADY seed, seems to be an effective tool to avoid bacterial alterations in CM vinifications.
... After AF, the obtained wine can go through malolactic fermentation (MLF), driven by lactic acid bacteria (LAB). It consists of the decarboxylation of l-malic acid into l-lactic acid (Kunkee, 1991;Lerm et al., 2010;Pilone & Kunkee, 1970), which results in a reduction of wine titratable acidity and an increase in pH (Davis et al., 1985;Liu, 2002;Lonvaud-Funel, 1999). Because MLF reduces acidity, it is highly recommended in red winemaking and in high acidity white wines. ...
The potential use of Torulaspora delbrueckii as a starter culture for wine alcoholic fermentation has become a subject of interest in oenological research. The use of this non‐Saccharomyces yeast can modulate different wine attributes, such as aromatic substances, organic acids and phenolic compound compositions. Thus, the obtained wines are different from those fermented with Saccharomyces cerevisiae as the sole starter. Nevertheless, information about the possible effects of T. delbrueckii chemical modulation on subsequent malolactic fermentation is still not fully explained. In general, T. delbrueckii is related to a decrease in toxic compounds that negatively affect Oenococcus oeni and an increase in others that are described as stimulating compounds. In this work, we aimed to compile the changes described in studies using T. delbrueckii in wine that can have a potential effect on O. oeni and highlight those works that directly evaluated O. oeni performance in T. delbrueckii fermented wines.
... The LAB are crucial in the vinification process of wines: some strains of Oenococcus oeni promote most of the time the progress of the malolactic fermentation (MLF) in red wines and part of white wines. They belong to the must and wine indigenous microbiota and develop spontaneously during or after alcoholic fermentation (Lonvaud-Funel, 1999;Lonvaud-Funel et al., 1991). Most of the time, the MLF proceeds satisfactorily but harsh conditions (low temperatures, low pH, etc.), or a low population of native bacteria can cause late onsets of MLF or languid fermentations. ...
In recent years, the frequency of occurrence of mousy off-flavours in wines has increased. This could be caused by the significant decrease in sulphur dioxide addition during processing, the increase in pH or even the trend for spontaneous fermentation in wine. This off-flavour was associated with Brettanomyces bruxellensis or lactic acid bacteria metabolisms. Three N-heterocyclic compounds (APY, ETHP, ATHP) were described as involved in mousiness perception. Thus far, no study addressed the variability in that N-heterocycles production according to microorganism strains from different species. Twenty-five wines presenting mousy off-flavour were analysed. In total, 252 bacteria with 90.5 % of Oenococcus oeni and 101 yeast strains with 53.5 % of Saccharomyces cerevisiae were isolated and identified. Their capacity to produce mousy compounds was investigated using Stir Bar Sorptive Extraction-Gas Chromatography-Mass Spectrometry (SBSE-GC-MS) and a standardised N-heterocycle assay medium. While four and three species of yeast and bacteria, respectively, were isolated from mousy wines, only three species of microorganisms were associated with N-heterocycles production: B. bruxellensis, Lentilactobacillus hilgardii and Oenococcus oeni. The screening was then extended to collection strains for these three species to improve their genetic representativity. Our results show that the levels and the ratios of the three N-heterocycles present huge variations according to the species. In addition, it has been shown that in most mousy wines, B. bruxellensis was not found. Finally, an interesting correlation between ATHP and ETHP was identified.
