Mannoproteins (MPs) are released from the yeast cell wall during alcoholic fermentation and aging on the lees, and influence aspects of wine quality such as haze formation and colour stability. Yet, as this is a slow process with microbiological and sensory risks, the exogenous addition of extracted MPs poses an efficient alternative. While Saccharomyces cerevisiae has long been studied as a prominent source for MPs extraction, their structure and composition greatly differ between yeast species. This may influence their behaviour in the wine matrix and subsequent impact on wine properties. However, although wine yeast species other than S. cerevisiae possibly present an untapped source of MPs, they are still ill-characterised in terms of chemical composition and influence on wine.
Organic volatile compounds as suitable markers of grapevine response to defense elicitors in the vineyard
In greenhouse, emission of volatile organic compounds (VOC) by grapevine leaves has already been reported in response to the defence elicitor sulfated laminarin (PS3) . In order to check that this response was not specific to PS3, experiments were conducted on Vitis cv Marselan plantlets with several other elicitors of different chemical structures: i.e. Bastid® (COS-OGA),
The development of a simple electrochemical method based on molecularly imprinted polymers for the selective determination of caffeic acid in wine
Caffeic acid (CA) is an antioxidant of great importance in the food sector, such as wine, where it acts as a marker of wine ageing, as well as in the health sector due to its antioxidant properties and beneficial effects including the prevention of inflammation, cancer, neurodegenerative diseases, and diabetes.
Avec l’accroissement des surfaces viticoles conduites en Bio, la question de l’impact de la présence de résidus de cuivre (seul anti fongique autorisé dans l’UE dans ce cadre Règlementaire) sur le déroulement des fermentations et sur les qualités œnologiques et organoleptiques des vins s’est révélée de plus en plus cruciale.
Polyphenols in kombucha: impact of infusion time on extraction and investigation of their behavior during “fermentation”
Kombucha is a non-alcoholic beverage made of sugared tea that is transformed by a symbiotic consortium of yeasts and bacteria. Polyphenols are expected to be responsible of several health benefits attributed to kombucha consumption, among other metabolites. This study investigated the impact of tea infusion time and of kombucha “fermentation”, on total phenolic content,
This study was performed on Chasselas wine to assess the impact of exposure to wine light according to several glass color of bottles. The aim was to highlight any differences whether from an organoleptic or analytical point of view depending on the color. For this, four different shades were compared, dead leaf, green, cinnamon and transparent. A control, not treated with light, was also included in the study. Several tests were carried out with different exposure times in boxes as well as in stores. The bottles were exposed 7 days, 4 days as well as 2 days in box but also 7 days in store. At the end of each test the different modalities were tasted by an expert panel in order to observe any differences between the tint modalities. As a result of these experiments, it was observed that organoleptic differences significant appeared after 2 days of exposure, in particular on the olfactory notes of the reduction. The transparent modality was seen to be significantly more intense on reduction scores compared to other modalities, including the witness in particular. These differences were also observed during all the tests even that of 7 days of exposure in store where we would have thought that there would be no difference. Overall, the control and cinnamon modalities are generally perceived to have more intense notes on the fruity, floral descriptors but less intense for reduction than the transparent shade. For the dead leaf and green modalities, the results are more contrasted and sometimes approach those of the control and other times closer to the transparent modality. Regarding the analytical results, similar conclusions could be drawn with respect to the sensory tests. In fact, the transparent modality is the variant which has an absorbance of the UV-C solution that is twice as high as the other modalities after the 7-day treatment in the chamber. In view of the sensory and analytical results obtained in this study, the choice of the color of the bottles turns out to be an essential element in influencing the intrinsic and extrinsic characteristics of a wine. In order to preserve the qualities of the wine over the medium and long term, dark and opaque tints should be favored. Conversely, a transparent glass could be recommended in the case of rapid consumption of the wine after bottling.
Reduction of sulfur dioxide during winemaking is a request from the wine industry. To replace sulfur dioxide, various alternatives exist, including bioprotection by yeast inoculation. This practice consists in adding non-Saccharomyces yeasts directly on the grapes or must.
Controlling the speed of alcoholic (AF) and malolactic (MLF) fermentations in wine can be an important challenge for the production of certain short rotation wines for entry-level market segments. Immobilization techniques for Saccharomyces cerevisiae and Œnococcus œni, the microorganisms responsible for these fermentations, are widely studied for industrial applications. Indeed, these processes allow to accumulate biomass and thus to increase cell densities inducing high fermentation velocities. Recent works have shown the performance of MLF carried out with biofilms of O. œni, immobilized on various supports in a rich medium (MRSm: modified MRS broth with malic acid and fructose).
From the current probabilistic approach to a deterministic production process, a clear step towards digital transformation in the wine sector
Currently, to consistently ensure the maintenance of a wine-style while benefiting from the utmost rigor made possible by the winemaking process, the composition of the wine blend is made using sensory control. This is performed after the wine is made with no real possibility of deterministic intervention.
Insufficient acidity in grapes from warm climates/vintages is commonly corrected through addition of tartaric acid during vinification, and less so with other organic acids. An alternative approach involves bio-acidification with the yeast Lachancea thermotolerans (LT) via lactic acid production during fermentation.
Vitamins are major compounds, involved in several prime yeast metabolic pathways. Yet, their significance in oenology has remained mostly unexplored for several decades and our current knowledge on the matter still remaining obscure to this day. While the vitaminic contents of grape musts have been approached in these ancient investigation
The bioprotection of musts or grapes is a strategy for limiting sulfiting during winemaking and more specifically at pre-fermentative step. The most preconized yeasts in bioprotection mainly belong to Metschnikowia pulcherrima and Torulaspora delbrueckii species. While previous studies have demonstrated that bioprotectant non-Saccharomyces strains were able to protect musts and wines against microbial spoilage as well as sulfites, they cannot protect must against oxidation which appears to be the main limit of this practice.
Plant fibers in comparison with other fining agents for the re-duction of pesticide residues and the effect on the volitile profile of Austrian white and red wines.
Pesticide residues in Austrian wines have so far been poorly documented. In 250 wines, 33 grape musts and 45 musts in fermentation, no limit values were exceeded, but in some cases high lev-els (>0.100 mg/l) of single residues were found, meaning that a reduction of these levels before bottling could make sense. In the course of this study, a white and a red wine were spiked with a mix of 23 pesticide residues from the group of fungicides (including botryticides), herbicides and insecticides. The influence of the following treatments on residue concentrations and volatile profiles were investigated: two activated charcoal products, a bentonite clay, two commer-cial mixed fining agents made of bentonite and charcoal, two yeast cell wall products, and a plant fiber-based novel filter additive. The results of this study show that all the agents tested reduced both residues and aromavolatile compounds in wine, with activated charcoal having the strongest effect and bentonite the weakest. The mixed agents and yeast wall products showed less aroma losses than charcoal products, but also lower residue reduction. Plant fibers showed good reduction of pesticides with moderate aroma damage, but these results need to be con-firmed under practical conditions.
Nowadays, winemaking is dealing with great challenges, notably climate change, disease resistance and low pesticide inputs, desire for more sustainable agricultural productions and permanent changing of consumer preference. Trying to propose practice improvements, scientists are exploring vine hybridization a paradoxically old but still actual way to take up such challenges
Oak wood barrel tannin potential builds white wines oxidative stability and contributes to wine metabolomics fingerprint
Considerable advances have been made in the chemical characterization of wine metabolites through its holistic study using both targeted and untargeted metabolomics approach. The metabolite pool is subject to an intense molecular dialogue which reinforces the wine complexity even after bottling.
The sporadic oxidation of white wines remains an open question, making wine shelf life a subjective debate. Through a multidisciplinary synoptic approach performed as a remarkable case study on aged bottles of white wine, this work unraveled a yet unexplored route for uncontrolled oxidation.
Amarone is an Italian red wine produced in the Valpolicella area, in north-eastern Italy. Due to its elaboration with withered grapes, Amarone is a rather unique example of dry red wine. However, there is very limited data so far concerning the volatile composition of commercial Amarone wines, which also undergo a cask aging of 2-4 years before release.
Impact of the maturity and the duration of maceration on phenolic composition and sensorial quality of Divico wines
Following its approval in 2013 by Agroscope, Divico became the first interspecific grape variety in Switzerland with high resistance to downy mildew (Plasmopara viticola) and grey rot (Botrytis cinerea), and medium resistance to powdery mildew (Uncinula nectator). Extremely riche in color, Divico grapes showed great enological potential to different styles of wine. Quickly, many wine growers were interested in planting this promising variety. Many of its potential are to be explored in the coming years.