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…

Effects of a new vacuum evaporation method on chemical and sensory properties of must and wine

A new process for vacuum evaporation was developed where evaporation takes place near the inner surface of a vortex produced by a rotor submerged in the liquid. Contrary to the state of the art the Vortex rotor process does not need a vacuum vessel but the rotating liquid creates a geometrically stable low pressure void surrounded by a vortex stabilized by the equilibrium between centrifugal forces and the pressure difference. First tests with water and sugar solutions at concentrations similar to grape must were conducted to verify the theoretical predictions, test the performance under different conditions and study the effect of various process parameters (Rösti et al 2015).

Anti/prooxidant activity of wine polyphenols in reactions of adrenaline auto-oxidation

Adrenaline (epinephrine) belongs to catecholamine class. It is a neurotransmitter and both a hormone which is released by the sympathetic nervous system and adrenal medulla in response to a range of stresses in order to regulate blood pressure, cardiac stimulation, relaxation of smooth muscles and other physiological processes. Adrenaline exhibits an effective antioxidant capacity (1). However, adrenalin is capable to auto-oxidation and in this case it generates toxic reactive oxygen intermediates and adrenochrome. Under in vitro conditions, auto-oxidation of adrenaline occurs in an alkaline medium (2).

To a better understanding of the impact of vine nitrogen status on volatile thiols from plot to transcriptome level

Volatile thiols contribute largely to the organoleptic characteristics and typicity of Sauvignon blanc wines. Among this family of odorous compounds, 3-sulfanylhexan-1-ol (3SH) and 4-methyl-4-sulfanylpentan-2-one (4MSP) have a major impact on wine flavor. These thiols are formed during alcoholic fermentation by the yeast from odorless and non-volatile precursors found in the berry and the must. The effect of vine nitrogen status on 3SH and 4MSP in Sauvignon blanc wine and on the glutathionylated and cysteinylated precursors of 3SH (Glut-3SH and Cys-3SH) was investigated in this study.

Elicitors used as a tool to increase stilbenes in grapes and wines

The economic importance of grapevine as a crop plant makes Vitis vinífera a good model system to study the improvement of the nutraceutical properties of food products (Vezulli et al. 2007). Stilbenes in general, and trans-resveratrol in particular, have been reported to be responsible for various beneficial effects. Resveratrol´s biological properties include antibacteria and antifungal effects, as well as cardioprotective, neuroprotective and anticâncer actions (Guerrero et al. 2010 ). Stilbenes can be induced by biotic and abiotic elicitors since they are phytoalexins (Bavaresco et al. 2001).

Impact of some agronomic practices on grape skins anthocyanin content

Wine colour is the first quality characteristic to be assessed, especially regarding red wines. Anthocyanins are very well known to be the main responsible compounds for red wine colour. Red cultivars can synthesize and accumulate anthocyanins in berry skin to express their colour. However, anthocyanin accumulation is often influenced by a series of factors, such as genetic regulation, phytohormones, environmental conditions and viticultural management.