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…

Moscatel vine-shoot extracts as grapevine biostimulant to increase the varietal aroma of Airén wines

There is a growing interest in the exploitation of vine-shoots waste, since they are often left or burned. Sánchez-Gómez et al. [1] have shown that vines-shoots aqueous extracts have significant contents of bioactive compounds, among which several polyphenols and volatiles are highlighted. Recent studied had demonstrated that the chemical composition of vine-shoots is enhanced when vine-shoots are toasted
[2,3]. The application of vegetable products in the vineyards has led to significant changes towards a more “Sustainable Viticulture”. An innovative foliar application for Airén vine-shoot extracts have been carried out to the vineyard. It has been shown that they act as grape biostimulants, improving certain wine quality characteristics [4].

How do different oak treatment affect the sensory composition of Chenin blanc wines over time?

Wooden barrels have been the preferred method for oak maturation for wines, but the use of alternative oak products, such as staves and oak chips have increased in South Africa due to lower production costs. This study investigated the effect of different oak products used during fermentation and ageing on the sensory profile, degree of liking and perceived quality of a South African Chenin blanc wine. The different wine treatments included an unoaked tank control wine, wines matured in 5th fill barrels, wines matured in new barrels from three different cooperages, and wines matured in 5th fill barrels with stave inserts from two different cooperages.

Characterization of commercial enological tannins and its effect on human saliva diffusion

Commercial oenological tannins (TECs) are widely used in the wine industry. TECs are rich in condensed tannins, hydrolyzable tannins or a mixture of both. Wine grapes are a important source of proanthocyanidins or condensed tannins while oak wood possess a high concentration of hydrolyzable tannins (Obreque-Slier et al., 2009). TECs contribute with the antioxidant capacity of wine, catalyze oxide-reduction reactions and participate in the removal of sulfur compounds and metals.

The effect of cropload on the volatile aroma characteristics of ‘Beihong’ and ‘Beimei’ red wine

Beihong and Beimei were bred as winemaking cultivars released by Institute of Botany, the Chinese Academy of Sciences in 2008. The cultivars are selected from the population of ‘Muscat Hamburg’ (Vitis vinifera) ×V. amurensis. They are extended to most provinces in North of China because they have strong resistance to cold and disease and need not be buried in soil in winter. To better understand the effect of cropload on volatile compounds during wine-making, we surveyed volatiles composition and content of different cropload level in 3-years-old ‘Beihong’ and ‘Beimei’ vines which planted in east foot of Helan mountain of Ningxia (EHN).

Wood from barrique: release of phenolic compounds and permeability to oxygen

Chemical and sensory changes occurring in red wine during ageing in oak barrique are due to the slow and gradual entrance of oxygen along with a release of ellagic tannin from the wood. Though oxygen can enter the cask through the bunghole, it is not clear the role of permeation through the wood staves as well as the amount of oxygen entering by permeation. The distribution of the released ellagic tannins in the wine ageing is also unknown. The oxygen passing through the bunghole may have a different wine ageing effect compared to the oxygen permeating through the wooden staves owing to the uneven ellagic tannin concentration throughout the wine.