Inactivation of Brettanomyces bruxellensis by High Hydrostatic Pressure technology

Póster presentado en el XXV Congreso de la Sociedad Española de Microbiología (SEM), celebrado en Logroño del 7 al 10 de julio de 2015.Peer Reviewe

Effect of kaolin silver complex on the control of populations of Brettanomyces and acetic acid bacteria in wine

In this work, the effects of kaolin silver complex (KAgC) have been evaluated to replace the use of SO2 for the control of spoilage microorganisms in the winemaking process. The results showed that KAgC at a dose of 1 g/L provided effective control against the development of B. bruxellensis and acetic acid bacteria. In wines artificially contaminated with an initial population of B. bruxellensis at 104 CFU/mL, a concentration proven to produce off flavors in wine, only residual populations of the contaminating yeast remained after 24 days of contact with the additive. Populations of acetic bacteria inoculated into wine at concentrations of 102 and 104 CFU/mL were reduced to negligible levels after 72 h of treatment with KAgC. The antimicrobial effect of KAgC against B. bruxellensis and acetic bacteria was also demonstrated in a wine naturally contaminated by these microorganisms, decreasing their population in a similar way to a chitosan treatment. Related to this effect, wines with KAgC showed lower concentrations of acetic acid and 4-ethyl phenol than wines without KAgC. The silver concentration from KAgC that remained in the finished wines was below the legal limits. These results demonstrated the effectiveness of KAgC to reduce spoilage microorganisms in winemaking.info:eu-repo/semantics/acceptedVersio

Impact of volatile phenols and their precursors on wine quality and control measures of Brettanomyces/Dekkera yeasts

Volatile phenols are aromatic compounds and one of the key molecules responsible for olfactory defects in wine. The yeast genus Brettanomyces is the only major microorganism that has the ability to covert hydroxycinnamic acids into important levels of these compounds, especially 4-ethylphenol and 4-ethylguaiacol, in red wine. When 4-ethylphenols reach concentrations greater than the sensory threshold, all wine’s organoleptic characteristics might be influenced or damaged. The aim of this literature review is to provide a better understanding of the physicochemical, biochemical, and metabolic factors that are related to the levels of p-coumaric acid and volatile phenols in wine. Then, this work summarizes the different methods used for controlling the presence of Brettanomyces in wine and the production of ethylphenols

A mathematical model of the link between growth and L-malic acid consumption for five strains of Oenococcus oeni

In winemaking, after the alcoholic fermentation of red wines and some white wines, L-malic acid must be converted into L-lactic acid to reduce the acidity. This malolactic fermentation (MLF) is usually carried out by the lactic acid bacteria Oenococcus oeni. Depending on the level of process control, selected O. oeni is inoculated or the natural microbiota of the cellar is used. This study considers the link between growth and MLF for five strains of O. oeni species. The kinetics of growth and L-malic acid consumption were followed in modified MRS medium (20 °C, pH 3.5, and 10 % ethanol) in anaerobic conditions. A large variability was found among the strains for both their growth and their consumption of L-malic acid. There was no direct link between biomass productivities and consumption of L-malic acid among strains but there was a link of proportionality between the specific growth of a strain and its specific consumption of L-malic acid. Experiments with and without malic acid clearly demonstrated that malic acid consumption improved the growth of strains. This link was quantified by a mathematical model comparing the intrinsic malic acid consumption capacity of the strains

Advances in the knowledge of lactic acid bacteria and management of wine associated microbiota using emerging technologies

El vino es el resultado de multitud de interacciones complejas entre una gran diversidad de microorganismos. El proceso de transformación de la uva en vino consta habitualmente de dos etapas fermentativas: la fermentación alcohólica, llevada a cabo por levaduras y la fermentación maloláctica, en la que las bacterias lácticas son los microorganismos principales. En este estudio se profundizó en el conocimiento de las comunidades de bacterias lácticas de vinos de Tempranillo de la Denominación de Origen Calificada Rioja (D.O.Ca. Rioja) a lo largo del proceso de elaboración. Para ello, se emplearon tanto técnicas de Biología molecular cultivo-dependientes como cultivo-independientes, resultando así complementaria la información obtenida. Se detectaron un gran número de especies de bacterias lácticas y de cepas de Oenococcus oeni, observándose en esta región un ecosistema diverso y maduro, donde tanto las especies como las cepas se fueron sucediendo como resultado de la adaptación a las condiciones de cada año, de cada bodega y de cada etapa de la vinificación. El estudio se completó con la comparación de las poblaciones dominantes de O. oeni de dos regiones vitivinícolas españolas (D.O.Ca. Rioja y D.O. Castilla-La Mancha). Dichas poblaciones se perfilaron como una única población panmíctica en la que algunas cepas de O. oeni parecían estar desarrollando una evolución clonal pero sin llegar a diferenciarse subpoblaciones alopátricas. La variabilidad de la microbiota observada implica que el control microbiológico sea indispensable para el desarrollo adecuado de las fermentaciones y para garantizar la calidad del vino. Para llevar a cabo este control microbiológico se han empleado tradicionalmente técnicas como el filtrado, la clarificación, así como la adición de sustancias químicas como el sulfuroso. Precisamente con la idea de reducir los aditivos habitualmente empleados en enología, en este trabajo de tesis doctoral también se estudiaron diferentes tecnologías emergentes, como pulsos eléctricos de alto voltaje, altas presiones hidrostáticas e irradiación de madera de barrica con microondas de alta frecuencia. En la mayoría de los casos se consiguió reducir la población inicial de los microorganismos presentes en las muestras tras la aplicación de estos tratamientos. Esta reducción sólo fue completa en el caso de la aplicación de altas presiones hidrostáticas para inactivar Brettanomyces bruxellensis. Por todo ello, se plantea que el control microbiológico de los vinos tendrá que abordarse con la aplicación combinada de más de una tecnología emergente alternativa al empleo de sulfuroso o con la optimización y desarrollo de nuevas tecnologías a nivel industrial.Peer Reviewe

Cold plasma at atmospheric pressure for eliminating Brettanomyces from oak wood

Trabajo presentado en Enoforum USA, celebrado online los días 4 y 5 de mayo de 202

Use of glutathione in the winemaking of white grape varieties

Glutathione is a tripeptide present in grapes, mostly in its reduced form (GSH), which plays a fundamental role in preventing oxidative processes in musts and wines. Its concentration in grapes is influenced by numerous agronomic factors and enological factors. The GSH addition in enological processes is an authorized practice that limits the oxidative reactions, avoiding the deterioration of the wine quality. The use of dry yeast preparations enriched with GSH in its reduced form in white musts at the beginning of the alcoholic fermentation is an interesting alternative to stop oxidations preserving the aroma and sensory quality of wines, especially in varieties with low nitrogen content and that are prone to brown. There are contradictory results regarding the influence of GSH on the organoleptic characterization of wines and so studies of the GSH antioxidant efficiency after the malolactic fermentation and during preservation, aging, or bottling are still necessary.This work has been co-financed by the Government of La Rioja and FEDER Funds during 2017

Oenococcus oeni strain typification by combination of Multilocus Sequence Typing and Pulsed Field Gel Electrophoresis analysis

Oenococcus oeni is usually the main lactic acid bacteria (LAB) responsible for conducting malolactic fermentation (MLF) in wines. Pulsed Field Gel Electrophoresis (PFGE) is one of the most common methods used to identify different genotypes among the wine LAB populations. Although PFGE is a powerful typing tool, it is time-consuming and its results are not easily exchangeable between laboratories so typing methods such as Multilocus Sequence Typing (MLST) have been developed. In this study, thirty O. oeni isolates from Rioja Tempranillo wines were characterized performing SfiI and ApaI PFGE and MLST with eight housekeeping genes. Using the latter technique, six new alleles have been described for five genes. PFGE was slightly more efficient than MLST because of the number of genotypes and of the index of diversity (ID) that each technique discriminated. This has been the first time that PFGE and MLST results have been combined to shape a unique dendrogram. Thus, the combination of results from both typing methods allowed the discrimination of twenty-two PFGE-ST genotypes showing the highest ID of these research (0.947). According to these results, the future application of the combination of PFGE and MLST results could be successful for reliable O. oeni strain typification. © 2013 Elsevier Ltd. All rights reserved

Indigenous lactic acid bacteria communities in alcoholic and malolactic fermentations of Tempranillo wines elaborated in ten wineries of La Rioja (Spain)

Indigenous lactic acid bacteria (LAB) communities have been analyzed for three years (2006, 2007 and 2008) during alcoholic (AF) and malolactic (MLF) fermentations of Tempranillo wines in ten wineries of La Rioja. The results showed that analytical composition of wines and physical-chemical conditions of elaboration influenced the LAB populations, the MLF duration and the percentage of each isolated species and strains. The highest diversity of LAB species was observed during AF in all the wineries. Oenococcus oeni was present in all studied stages of the fermentation process, being the predominant species at final AF stage. The study of 925 isolates of O. oeni by Pulsed Field Gel Electrophoresis (PFGE) allowed the detection of a total of 112 distinct genotypes. Most fermentation stages of both AF and MLF showed mixed O. oeni strain populations, so that there were different genotypes able to share their ecological niche or tank in spontaneous MLF. The frequency of participation of each genotype varied either from year to year or from winery to winery. Otherwise, seven genotypes were detected in the three studied years and in at least three out of the ten studied wineries, being four of them also present in the three studied subzones of this region. These results suggest the existence of an endemic microbiota in this region, the adaptation of indigenous O. oeni strains to the winery conditions every year and the interest of selecting predominant genotypes in order to preserve the biodiversity and peculiarity of these wines. © 2012 Elsevier Ltd