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…

How pressing techniques affect must composition and wine quality of Pinot blanc

This study investigates how the sensory profile of Pinot Blanc is affected from different maceration and pressing techniques. Grapes were sourced from four vineyards in the village Tramin in South Tyrol. For the experiment 200 kg of grapes from each vineyard site were hand picked the day before harvest for the commercial winery took place. Grapes were stored over night at 4°C, homogenized and processed in the experimental winery at Laimburg research centre the day after harvest. Four different pressing techniques were applied in duplicates of 100kg each.

Interaction between the enzymes of central carbon metabolism and anthocyanin biosynthesis during grape berry development

Primary and secondary metabolites are major components of grape quality and wine typicity. Their accumulation is interconnected through a complex metabolic network, which is still not well understood. This study aims to investigate how the enzymes of central carbon metabolism interact with anthocyanin biosynthesis during grape berry development: does the accumulation of anthocyanins, which represents a non-negligible diversion of carbon metabolic fluxes, require reprogramming of central enzymes or is it controlled downstream of central metabolism? To this end, 23 enzymes involved in central carbon metabolism pathways have been analyzed in the berries of 3 grape cultivars, which have close genetic background but distinct temporal dynamics of anthocyanin accumulation.

Characterization of free and glycosidically bound simple phenols in hybrid grape varieties using liquid chromatography coupled to high resolution mass (q-orbitrap)

Vitis vinifera is one of the most diffused grapevines over the word and it is the raw material for high quality wines production. The availability of more resistant interspecific hybrid vine varieties, developed from crosses between Vitis vinifera and other Vitis species, has generating much interest, also due to the low environmental effect of production. However, hybrid grape wine composition and varietal differences between interspecific hybrids are not well defined. Different studies revealed that wine consumption has health effects due to its high content of antioxidants, as phenolic compounds. In particular, simple phenols are appreciated not only for their physiological health benefits, including antioxidant, anti-inflammatory and cardioprotective effects, but also because they affect wines organoleptic profile and have a significant role in defining their nutritional characteristics.

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].

Flavanol glycosides in grapes and wines : the key missing molecular intermediates in condensed tannin biosynthesis ?

Polyphenols are present in a wide variety of plants and foods such as tea, cacao and grape1. An important sub-class of these compounds is the flavanols present in grapes and wines as monomers (e.g (+)-catechin or (-)-epicatechin), or polymers also called condensed tannins or proanthocyanidins. They have important antioxidant properties2 but their biosynthesis remains partly unknown. Some recent studies have focused on the role of glycosylated intermediates that are involved in the transport of the monomers and may serve as precursors in the polymerization mechanism3, 4. The global objective of this work is to identify flavanol glycosides in grapes or wines, describe their structure and determine their abundance during grape development and in wine.