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

Ohmic heating for polyphenol extraction from grape berries: An innovative prefermentary process

High energy consumption is often required to increase the extraction of phenolic compounds from grapes during alcoholic fermentation. Processes such as thermovinification require significant temperature changes over a long period of time to ensure the diffusion of phenolic compounds from the grape skin layer to the must. In this study, the capability of the ohmic heating (OH) process (E = 55 V/cm, t = 60-90 s, T = 72 °C) to improve the extractability of valuable intracellular compounds from grape skins of Aglianico and Barbera grape matrices before the alcoholic fermentation stepAs similarly reported by Donsì et al. (2010), any tissue damage to grape skins occurring after the application of either conventional or ohmic heating was not found to influence the rate of fermentation. was investigated and compared with both untreated and conventional thermally (CH) treated (T = 72 °C, t = 90 s) samples. Total phenolics and antioxidant capacity were monitored during fermentation (10 days). In comparison to the conventional thermal treatment, the results showed that the phenolic compound content of musts was twice as high immediately after OH treatment. This process could drastically improve the classic prefermentary maceration (thermovinifications, cold macerations, etc.) time. In finished wines produced from the treated musts, the total polyphenolic content of OH wines was up to 17 % higher than that of CH wines, and 30 % higher than that of untreated wines. No differences in concentrations of total tannins and anthocyanins were observed between conventional and ohmic heated musts. However, an increase of 30 to 200 % for some aromatic esters was observed in wines from ohmic heated musts. Overall, the outcomes of this work proved that, in addition to the thermal effect, the moderate electric field (MEF) applied during ohmic heating has the potential to induce an instantaneous release of polyphenolic compounds due to the electroporation phenomenon of cell membranes, thus saving energy and reducing processing time

Impact of high-power ultrasound for barrel regeneration on the extraction of wood volatile and non-volatile compounds

High-power ultrasound (HPU) is an innovative cleaning method used in wineries for oak barrel sanitation and regeneration. The process is associated with hot water (HPUhw ) to ensure microbial stabilization and has been proved to be highly effective in recent years. This study thus examines the impact of different cleaning treatments on the subsequent extraction of wood compounds in wine and their impact on organoleptic properties. Red wines aging in barrels treated (HPUhw and steam) in different years (1, 2, and 3 years) were examined during the first 12 months for chemical exchange from wood to wine. Specific analyses were realized on ellagitannins, the physicochemical composition, and oak wood volatile compounds. Only a small increase in some wood volatile compounds occurred in the case of HPUhw, including furfural, 5-methylfurfural, trans-whisky lactone, vanillin, and syringaldehyde. The sensory analysis carried out by a panel of experts showed that the impact on the organoleptic properties of wines is similar with both processes (HPUhw and steam). However, since HPUhw treatment requires lower energy for the same efficiency, it could be an interesting alternative to steam treatment, given the promising prior microbial results

A New Test of Filterability for Unprocessed Wines Evaluation of the Enzyme Efficiency

A new Test of Filterability has been developed. Measurements carried out with different types of wines indicate that the new filterability index is a useful tool for understanding and predicting the propensity to fouling of treated or untreated wines, e.g. with or without enzyme addition. The measurement method used in the Test of Filterability, requires only one type of membrane for all types of wine, and uses the same equipment as the traditional Fouling Index. Numerous trials have demonstrated that the filtration of wines is governed by standard blocking law. The definition of the new Test of Filterability, based on this filtration law, is proposed. The choice of membrane and the selection of the optimal pore size were based on the results of the experiments. Current methods used for the determination of fouling properties in wine filtration have been developed for the membrane filtration of small quantities of suspended matter. Enzyme treatment is a process often used in wine clarification. The new Test of Filterability indicates the best conditions for the filtration of all types of wines. The test is easy to implement and has been validated with various wines. This new Test of Filterability is an important tool for winemakers as it constitutes a simplified test of a wine's filterability. The new test may also be used to determine the filtration process that is best adapted to each wine while reducing the number of operations. The same approach may be adopted for the filtration of other liquids.&nbsp

The use of nanofiltration membranes for the fractionation of polyphenols from grape pomace extracts

Filtration experiments in batch concentration mode (with recycling of the retentate stream) of grape pomace extract were performed in laboratory filtration membrane equipment by using nine commercial nanofiltration (NF) membranes with an approximate molecular weight cut-off (MWCO) of 1000‒150 Da. The filtration experiments of the selected pomace extract were performed by modifying the most important operating variables: transmembrane pressure, tangential velocity, temperature, and the nature and MWCO of the membranes. The evolution of the cumulative permeate volumes and permeate fluxes with processing time was analyzed till a volume reduction factor (VRF) of 10 was reached. The effect of the mentioned operating conditions was discussed. The effectiveness of the filtration treatments was determined by the evaluation of the rejection coefficients for several families of polyphenols. Membranes possessing MWCO between 1000 and 500 Da were able to quantitatively recover polymeric proanthocyanidins in the concentrate stream and separate them from phenols that passed through the membrane into the permeate stream. On the other hand, the 600 to 300 Da membranes could also be used for the fractionation of monomeric phenolic families. The membranes were able to partially remove the anthocyanin fragments of phenolic acid derivatives and flavonols in the concentrate stream and at the same time

Étude numérique des champs mécaniques locaux dans les agrégats polycristallins sous chargements cycliques

Dans les pièces mécaniques soumises à des sollicitations cycliques, les déformations répétées engendrent le phénomène de fatigue. Dans le cas des polycristaux, on constate une localisation de ces déformations qui conduit à la formation de fissures courtes dont l'amorçage et la micropropagation sont pilotés par les paramètres de la microstructure du matériau, comme l'orientation des grains et les joints de grains. Cette dépendance, associée aux multitudes de configurations microstructurales possibles, explique la forte dispersion des résultats d'essais en fatigue. L'étude numérique proposée se base sur des calculs d'agrégats polycristallins par Éléments Finis avec un modèle de plasticité cristalline sous différentes conditions de chargements cycliques. Ces derniers sont réalisés sur des microstructures tridimensionnelles synthétiques (décomposition de Voronoï) et réelles (EBSD avec polissages successifs). Plusieurs configurations d'orientations sont prises en compte afin de reproduire les effets de dispersion observés expérimentalement. Les résultats des simulations sont analysés au cas par cas d'une part, et par traitement statistique d'autre part. L'objectif est de rendre compte de l'effet des paramètres de la microstructure, tels que le facteur de Schmid sur la formation des fissures courtes de fatigue. Les marches d'extrusion et intrusion en surface, considérés comme les sites critiques menant à l'amorçage des fissures courtes, sont reproduites numériquement et comparées à la microstructure réelle fissurée. La prédiction de ces marches est en bonne concordance avec les observations expérimentales, dès lors qu'elles apparaissent dans des grains assez larges en surface. On observe également une nocivité accrue sous chargement équibiaxial. L'analyse des distributions des champs locaux permet d'analyser quantitativement l'hétérogénéité des contraintes à l'échelle locale

Effects of working parameters on the surface roughness in belt grinding process: the size-scale estimation influence

This paper outlines a new method to evaluate roughness parameters considering the scale used for their evaluation. Application is performed for grinding hardened steel with abrasive belts. Seven working variables are considered through a two-level experimental design. For all configurations, 30 surface profiles were recorded by tactile profilometry and rectified by a first degree B-spline fitting before calculating a set of current roughness parameters. The relevancy of each roughness parameter, to highlight process parameters influence, is then estimated for each scale by variance analysis. The results show that each influent input parameter is characterised by a related relevant evaluation length

Comparative scoping study report for the extraction of microalgae oils from two subspecies of Chlorella vulgaris

The production of microalgae as a fatty acid oil resource for use in biofuels production is a widespread research topic at the lab scale. Microalgae contain a higher lipid content on a dry-weight basis compared to oilseeds such as soybeans. Additionally, the growth and cultivation cycle of microalgae is 15 days, in comparison to soybeans, for which the cycle occurs once or twice annually. However, to date, it has been uneconomical to produce microalgae oils in a world-scale facility due to limitations in cultivating microalgae at commercial scales. Recent developments suggest that the use of heterotrophic microalgae may be economically feasible for large-scale oil production. To assess this feasibility, a comparative scoping study was performed analysing the feasibility of an industrial-scale process plant for the growth and extraction of oil from microalgae. Processes were developed at the preliminary design level using heterotrophic subspecies and autotrophic subspecies of Chlorella vulgaris. AACE Class 4 cost estimates and economic analyses were performed. This study concludes that processes based on heterotrophic microalgae are more likely to reach economic feasibility than processes using autotrophic microalgae. However, a few barriers still remain to achieving free-market economic viability

Binoculars

Binoculars, taken by Emily Ghidossi on the Linfield University January Term Program in Argentina. 3rd place, Students division, in the 2025 Linfield University Study Abroad Photo Contest.https://digitalcommons.linfield.edu/intl_photos2025/1011/thumbnail.jp