Macrowine 2021
IVES 9 IVES Conference Series 9 Full automation of oenological fermentations and its application to the processing of must containing high sugar or acetic acid concentrations

Full automation of oenological fermentations and its application to the processing of must containing high sugar or acetic acid concentrations

Abstract

Climate change and harvest date decisions have led to the evolution of must quality over the last decades. Increases in must sugar concentrations are among the most obvious consequences, quantitatively. Saccharomyces cerevisiae is a robust and acid tolerant organism. These properties, its sugar to ethanol conversion rate and ethanol tolerance make it the ideal production organism for wine fermentations. Unfortunately, high sugar concentrations may affect S. cerevisiae and lead to growth inhibition or yeast lysis, and cause sluggish or stuck fermentations. Even sublethal conditions cause a hyperosmotic stress response in S. cerevisiae which leads to increased formation of fermentation by-products, including acetic acid, which may exceed legal limits in some wines. Recently, an innovative fermentation system based on FT-NIR and modern process technology was developed by our group, allowing fully automated alcoholic fermentations. The system provides accurate real-time information about key-fermentation parameters including glucose, fructose, and ethanol concentrations throughout fermentations. This allows carrying out fed-batch fermentations at constant and low sugar concentrations thus reducing the hyperosmotic stress response of S. cerevisiae. In this research project, the automated fed-batch technique was compared to the traditional batch method and applied to the vinification of a white Chasselas (Gutedel) grape must under practical winery conditions. A research grade FT-NIR spectrophotometer with an InGaAs detector and an external transflectance probe was used providing non-destructive and non-diffusion limited in-line measurement of sugars. The population dynamics of Saccharomyces cerevisiae and apiculate yeast were followed throughout the fermentations, and samples were also analyzed for organic acids, glycerol, primary amino acids, ammonia, and aldehydes. The final wines were subjected to discrimination (2/5) and descriptive sensory (free sorting) analyses by a trained expert panel. The fed-batch technique allowed drastically reducing the titer (1-2 orders of magnitude) and impact of apiculate yeast. This lead to significantly different wines that were rated as being free of defects and fruitier by the trained panel. The kinetics of several key-wine compounds also differed considerably. Wine produced with the fed-batch technique contained no acetic acid and significantly reduced acetaldehyde levels. The research demonstrates the potential for the application of the fed-batch technique for high gravity musts, but also for musts with a high microbiological load. The drastic reduction of acetic acid concentrations offers a biological alternative to the membrane technology based reduction of acetic acid in musts and wines.

Publication date: May 17, 2024

Issue: Macrowine 2016

Type: Poster

Authors

Ramon Mira de Orduna*, Arnaud Pernet, Charles Frohmann, Danielle Widmer, Jean-Pascal Bourgeois, Julien Richard, Olivier Vorlet

*HES-SO

Contact the author

Tags

IVES Conference Series | Macrowine | Macrowine 2016

Citation

Related articles…

Anthropogenic factors in modulations of fungal populations from grapes to wines and their repercussions on wine characteristics

The effects of anthropogenic activities on vineyard (different plant protections) and in winery
(pressing/clarification step, addition of sulfur dioxide) on fungal populations from grape to wine were studied. The studied anthropogenic activities modify the fungal diversity. Thus, lower biodiversity of grapes from organic modality was measured for the three vintages considered compared to biodiversity from ecophyto modality and conventional modality. The pressing / clarification steps strongly modify fungal populations and the influence of the winery flora is highlighted.

Micro-meteorological, compositional and transcriptional study of corvina grape color during ripening

Grape anthocyanin content and composition could affect the quality and the production strategies of red wines. Differences in the pigment composition modify the color properties in terms of hue, extractability and stability. Thus, for the production of a highly qualitative wine such as “Amarone”, variations in the pigment composition are not negligible. The aim of this work was the investigation of the anthocyanin profile changes during ripening in Corvina grapes, the main cultivar for the “Amarone” production. The experiment took place in 2015, in two vineyards located in Valpollicella (Italy).

Interest and impact of PVP/PVI (Polyvinylpyrrolidone/ Polyvinylimidazole) on winemaking and final quality of wines

Céline Sparrow a, Christophe Morge a, a SOFRALAB SAS, 79, av. A.A. Thévenet – CS 11031 – 51530 Magenta, France Consumers’ health and security force authorities to limit, in wine as in others food industry products, the concentration in « dangerous » molecules. Therefore the legal limit in heavy metals keeps on decreasing. As per proof EU regulation just decrease the stain concentration in wine from 0,2 to 0,15 mg/l. Certain changes , such as sodium arsenite treatment in vines, disappearance of brass in wineries to the benefit of stainless steel, limit even more the concentration of heavy metals in wines. But the use of copper derivates in vines treatments is difficult to replace. In the case of wine and its elaboration, the problem is even more complex. Indeed, regulation forces the wine producers to control the concentration of certain heavy metals in final wines.

The influence of soil management practices on functional traits and biodiversity of weed communities in Swiss vineyards

Green cover in vine rows provides many ecological services, but can also negatively impact the crop, depending on the weed species. The composition of a vineyard weed community is influenced by many parameters. Ensuring an evolution of the vine row flora into a desired direction is therefore very complex. A key step towards this goal is to know which factors influence the establishment of the weed community and which types of communities are best suited for vineyards. In this study, we analysed the weed communities of several vineyards in the Lake Geneva region (379 botanical surveys on 117 plots), with the aim to highlight the links between soil management practices (chemical and mechanical weeding, mowing, mulching roll) and phytosociological profiles, biodiversity and selected functional traits (growth forms, life strategies, root depth). T

On the losses of dissolved CO2 from laser-etched champagne glasses under standard tasting conditions

Under standard champagne tasting conditions, the complex interplay between the level of dissolved CO2 found in champagne, its temperature, the glass shape, and the bubbling rate, definitely impacts champagne tasting by modifying the neuro-physico-chemical mechanisms responsible for aroma release and flavor perception. Based on theoretical principles combining heterogeneous bubble nucleation, ascending bubble dynamics and mass transfer equations, a global model is proposed (depending on various parameters of both the wine and the glass itself), which quantitatively provides the progressive losses of dissolved CO2 from laser-etched champagne glasses.