Microbial stabilization of grape musts and wines using coiled UV-C reactor

UV-C light is well known for its germicidal properties and is widely used for water disinfection. However, its low penetration into absorbing liquids, such as wines and musts, reduces drastically the microbial inactivation effectiveness. Additionally, wines require UV-C doses to be as low as possible to avoid any possible light-struck flavors. In order to add to the technologies that allow the reduction of SO2 use, a coiled UV-C reactor was designed to inactivate microorganisms in wines and musts. Due to its unique hydrodynamic characteristics, this design could improve the exposure probabilities of the microorganisms to the UV-C light in absorbing liquids. In a first step, theoretical and measured fluid dynamics parameters such as Dean number were employed to improve the operating conditions of the reactor. The higher the Dean number, the higher the UV-C dose delivery efficiency in this reactor, and thus the lower the dose required to inactivate a given load of microorganisms. The second step investigated the impact of different wines on microbial inactivation efficiency and the UV-C doses required to inactivate microorganisms frequently found in wines. White and rosé wines, with low absorbances at 254 nm, required lower doses (≈ 600 J/L) than red wine (≈ 5000 J/L) because their absorption coefficient is ten times lower. The tolerance of microbial strains to UV-C treatments was variable, with higher resistance observed for yeast than for bacteria. In the third step, treatments conducted at semi-industrial scale showed that physicochemical and sensorial properties of wines and musts were not altered, highlighting the possible relevance of such a reactor on an industrial scale. Highlights: • Design of a coiled UV-C reactor for microbial stabilization of wines and musts• Focus on inactivation efficiency in multiple strains and wine varieties• Chemical and sensorial analyses to ensure treatment does not affect the organoleptic properties of the produc

Yeast and filamentous fungi microbial communities in organic red grape juice : effect of vintage, maturity stage, SO2, and bioprotection

Changes are currently being made to winemaking processes to reduce chemical inputs [particularly sulfur dioxide (SO2)] and adapt to consumer demand. In this study, yeast growth and fungal diversity were investigated in merlot during the prefermentary stages of a winemaking process without addition of SO2. Different factors were considered, in a two-year study: vintage, maturity level and bioprotection by the adding yeast as an alternative to SO2. The population of the target species was monitored by quantitative-PCR, and yeast and filamentous fungi diversity was determined by 18S rDNA metabarcoding. A gradual decrease of the α-diversity during the maceration process was highlighted. Maturity level played a significant role in yeast and fungal abundance, which was lower at advanced maturity, while vintage had a strong impact on Hanseniaspora spp. population level and abundance. The presence of SO2 altered the abundance of yeast and filamentous fungi, but not their nature. The absence of sulfiting led to an unexpected reduction in diversity compared to the presence of SO2, which might result from the occupation of the niche by certain dominant species, namely Hanseniaspora spp. Inoculation of the grape juice with non-Saccharomyces yeast resulted in a decrease in the abundance of filamentous fungi generally associated with a decline in grape must quality. Lower abundance and niche occupation by bioprotection agents were observed at the overripened stage, thus suggesting that doses applied should be reconsidered at advanced maturity. Our study confirmed the bioprotective role of Metschnikowia pulcherrima and Torulaspora delbrueckii in a context of vinification without sulfites

A922 Sequential measurement of 1 hour creatinine clearance (1-CRCL) in critically ill patients at risk of acute kidney injury (AKI)

Meeting abstrac

Extracorporeal Membrane Oxygenation for Severe Acute Respiratory Distress Syndrome associated with COVID-19: An Emulated Target Trial Analysis.

RATIONALE: Whether COVID patients may benefit from extracorporeal membrane oxygenation (ECMO) compared with conventional invasive mechanical ventilation (IMV) remains unknown. OBJECTIVES: To estimate the effect of ECMO on 90-Day mortality vs IMV only Methods: Among 4,244 critically ill adult patients with COVID-19 included in a multicenter cohort study, we emulated a target trial comparing the treatment strategies of initiating ECMO vs. no ECMO within 7 days of IMV in patients with severe acute respiratory distress syndrome (PaO2/FiO2 <80 or PaCO2 ≥60 mmHg). We controlled for confounding using a multivariable Cox model based on predefined variables. MAIN RESULTS: 1,235 patients met the full eligibility criteria for the emulated trial, among whom 164 patients initiated ECMO. The ECMO strategy had a higher survival probability at Day-7 from the onset of eligibility criteria (87% vs 83%, risk difference: 4%, 95% CI 0;9%) which decreased during follow-up (survival at Day-90: 63% vs 65%, risk difference: -2%, 95% CI -10;5%). However, ECMO was associated with higher survival when performed in high-volume ECMO centers or in regions where a specific ECMO network organization was set up to handle high demand, and when initiated within the first 4 days of MV and in profoundly hypoxemic patients. CONCLUSIONS: In an emulated trial based on a nationwide COVID-19 cohort, we found differential survival over time of an ECMO compared with a no-ECMO strategy. However, ECMO was consistently associated with better outcomes when performed in high-volume centers and in regions with ECMO capacities specifically organized to handle high demand. This article is open access and distributed under the terms of the Creative Commons Attribution Non-Commercial No Derivatives License 4.0 (http://creativecommons.org/licenses/by-nc-nd/4.0/)

Procédés innovants pour la stabilisation microbiologiques des vins

Article dans une revue professionnell

Rayonnement UV-c et stabilisation microbiologique des moûts et des vins

Article dans une revue professionnelleLa recherche de procédés innovants permettant d’assurer la stabilisation microbiologique des vins suscite un intérêt considérable pour la profession. L’objectif de cette recherche est de développer un procédé éco-innovant permettant de limiter l’emploi de dioxyde de soufre. L’effet germicide des UV-C maximal est atteint à une longueur d’onde de 254 nm. Cette longueur d’onde énergétique conduit à la formation de dimères de pyrimidine sur les brins d’ADN, qui une fois endommagés, ne peuvent plus être dupliqués. La multiplication des micro-organismes est ainsi bloquée. L’objectif de ce projet est de permettre un contact optimum entre les micro-organismes et ces rayons (donc, d’optimiser la transmittance) sans modifier les caractéristiques organoleptiques des vins. Ainsi, ces essais ont permis d’obtenir des premières références sur l’efficacité de différentes intensités de traitement aux UV-C sur le niveau d’abattement microbiologique sur différentes espèces (S. cerevisiae FX10, B. bruxellensis CBS2499, B. bruxellensis AWRI1608 et des bactéries de type A. aceti et E. œni SB3) sur plusieurs vins (blancs, rouges, rosées et liquoreux) et d’évaluer l’incidence de ce traitement sur les caractéristiques analytique et sensorielle. Pour chaque matrice et micro-organisme étudié, nous avons pu déterminer une dosimétrie permettant d’assurer la stabilisation microbiologique sans incidence au niveau physico-chimique et sensoriel après 12 mois d’élevage

ScanPEP un nouvel outil d’evaluation de la maturité des pépins.

Article dans une revue professionnell

La bioprotection en œnologie: Impacts microbiologiques et conséquences œnologiques

Article de revue professionnelleLa bioprotection est définie comme un procédé visant à appliquer un microorganisme vivant dans le but de coloniser le milieu dans lequel il est ensemencé, afin de limiter le développement d’une flore non qualitative et les altérations qu’elle génère. Dans la pratique, il s’agit très souvent de levures de type non-Saccharomyces. Ce terme regroupe en réalité un ensemble très hétérogène de genres et d’espèces dont nombre d’entre eux sont délétères à la qualité du vin. Le choix du microorganisme doit donc reposer à la fois sur des critères liés à l’espèce (faiblement fermentaire mais ayant la capacité de se maintenir dans le moût ; ne générant pas de défauts), mais aussi à la souche puisqu’au sein de la première, il existe une grande variabilité. De plus, la diversité des contextes œnologiques dans lesquels les agents de bioprotection sont utilisés constitue un paramètre supplémentaire à prendre en compte lors de leur sélection et leur mise en œuvre : les microorganismes choisis doivent être suffisamment robustes pour s’adapter à nombre de situations. Ici, il sera fait mention d’un mélange de deux souches, l’une provenant de l’espèce Torulaspora delbrueckii, l’autre de l’espèce Metschnikowia pulcherrima, ce qui nous a semblé être la solution optimale pour répondre à l’ensemble de ces contraintes. L’utilisation d’agents de bioprotection s’inscrit principalement (mais pas seulement) dans un contexte de diminution du SO2 et pour l’instant s’applique uniquement sur vendange et sur moût. En effet, les vinificateurs cherchent depuis quelques années à limiter et même bannir l’utilisation du dioxyde de soufre lors du processus de vinification. Néanmoins, les données scientifiques sur les mécanismes exacts qui sous-tendent l’application de la bioprotection et ses conséquences œnologiques sont encore trop rares

Bioprotection as an alternative to SO₂ in the pre-fermentation phase

Additives have been used in the food industry for many years, to prevent food spoilage and extend shelf life. These chemical additives are a source of controversy and their use must be reduced in the face of societal demand. In enology, this applies in particular to sulfur dioxide (SO2). There has been recent research on bioprotection as an alternative to sulfite addition in the pre-fermentation phase. This technical article discusses the many advantages of using bioprotection agents

Does metformin exposure before ICU stay have any impact on patients’ outcome? A retrospective cohort study of diabetic patients

Abstract Background Impact of metformin exposure before ICU stay remains controversial. Metformin is thought to induce lactic acidosis and haemodynamic instability but may reduce ICU mortality. We evaluated its influence on outcome in diabetic patients admitted in the ICU and then compared two different populations based on the presence of septic shock. Methods We conducted a retrospective cohort study in a 24-bed French ICU between October 2010 and December 2013, including all ICU-admitted diabetic patients. Results Among 635 diabetic patients admitted during the study period, 131 (21%) were admitted with septic shock. Multivariate analysis showed no difference in hospital mortality in all metformin users (OR 0.75 [95% CI 0.44–1.28]; p = 0.29), except in the septic shock subgroup (OR 0.61; 95% CI [0.37–0.99]; p = 0.04) despite higher vasopressor dosages in the first hours after shock onset. Blood lactate level was higher in metformin users than in non-metformin users in all patients (p < 0.001), in septic shock patients (p < 0.001) and in patients without kidney injury (p < 0.001). Metformin users did not have more septic shock from unknown aetiology (p = 0.65) or unknown pathogen (p = 0.99). Conclusions Metformin use before admission to ICU did not affect in-hospital mortality. However, for patients with septic shock, mortality was lower, despite worse clinical presentation on admission. Blood lactate levels were always higher with or without septic shock and indifferent of kidney function