Macrowine 2021
IVES 9 IVES Conference Series 9 Evaluation of three alternative strategies for the long-term remediation of reductive off-odours in wines

Evaluation of three alternative strategies for the long-term remediation of reductive off-odours in wines

Abstract

Sulfur-like off-odours are a problem caused by the presence of free forms of volatile sulphur compounds (VSCs). H2S is the most frequently found above its odour threshold (1-10 µg/L), followed by methanethiol (MeSH). Recent evidences showed that the usual treatments to eliminate VSCs from wine e.g.: addition of Cu salts or micro-oxygenation only delay the occurrence of reductive off-odours. (Vela et al., 2017, 2018) The present work aims to assess the effectiveness of three alternative remediation strategies on the removal of VSCs:

1.- intensive oxygenation in the presence of a 3-mercaptopropyl-functionalized adsorbent (MPS);

2.- purging out with N2 the wine stored in reductive conditions; and,

3.- incubation with lees. The treatment with MPS consisted in the addition of 1 mM (of -SH groups) of the functionalized adsorbent to two different wines.

They were further saturated with air and, after three days, were centrifuged and analysed. The purge with N2 was applied to two different wines, which had been previously stored during 2 weeks at 50ºC under anoxia. They were purged at 100 mL/min during 60 min and analysed after the treatment. For lees treatment, three different types of lees were studied: fresh active lees, fresh inactive lees and commercial inactivated dry yeast. They were added (3,3 g/L) to wines with reductive off-odour, then they were incubated for 16 weeks at 25ºC, with weekly agitation. After the incubation, the wines were centrifugated to remove the lees. VSCs and redox potential of wines were analysed by GC-SCD (Ontañón et al., 2019) before and after each essay. Additionally, after the treatments an accelerated reductive aging was carried out (incubation at 50ºC under anoxia for 2 weeks) to assess the long-term effect of the treatments. Intensive oxygenation was very effective (-85% H2S BR after treatment and accelerated aging in both cases). Purge treatment was effective only in the short time, removing completely free H2S free and -70% BR-H2S. However, it was not effective in the long-term. The use of inactivated dry yeast was ineffective. The use of active or inactive fresh lees was effective only in some cases. In conclusion, oxidation with MPS provides the most effective treatment; purging was effective only in the short-term; and treatments with lees were not conclusive. Further studies to assess side effects of oxidation with MPS on wine characteristics should be carried out.

DOI:

Publication date: September 13, 2021

Issue: Macrowine 2021

Type: Article

Authors

Diego Sánchez-Gimeno

Diego Sánchez-Gimeno, Laboratory  of Aroma Analsis and Oenology (LAAE), Instituto Agroalimentario de Aragón –IA2-; Departamento de Química Analítica, Facultad de Ciencias, Universidad de Zaragoza, 50009. Zaragoza, Spain,Ignacio Ontañon, LAAE, –IA2- Universidad de Zaragoza Vicente Ferreira, LAAE, –IA2- Universidad de Zaragoza

Contact the author

Keywords

reduction, off-odours, vscs, lees, purge

Citation

Related articles…

Assessing the relationship between cordon strangulation, dieback, and fungal trunk disease symptom expression

Grapevine trunk diseases including Eutypa dieback are a major factor in the decline of vineyards and may lead to loss of productivity, reduced income, and premature reworking or replanting. Several studies have yielded results indicating that vines may be more likely to express symptoms of vascular disease if their health is already compromised by stress. In Australia and many other wine-growing regions it is a common practice for canes to be wrapped tightly around the cordon wire during the establishment of permanent cordon arms. It is likely that this practice may have a negative effect on health and longevity, as older cordons that have been trained in this manner often display signs of decay and dieback, with the wire often visibly embedded within the wood of the cordon. It is possible that adopting a training method which avoids constriction of the vasculature of the cordon may help to limit the onset of vascular disease symptom expression. A survey was conducted during the spring of two consecutive growing seasons on vineyards in South Australia displaying symptoms of Eutypa lata infection when symptomless shoots were 50–100 cm long. Vines were assessed as follows: (i) the proportion of cordon exhibiting dieback was rated using a 0–100% scale; (ii) the proportion of canopy exhibiting foliar symptoms of Eutypa dieback was rated using a 0–100% scale; (iii) the severity of strangulation was rated using a 0–4 point scale. Images were also taken of each vine for the purpose of measuring plant area index (PAI) using the VitiCanopy App. The goal of the survey was to determine if and to what extent any correlation exists between severity of strangulation and cordon dieback, in addition to Eutypa dieback foliar symptom expression.

austrianvineyards.com: online viewer of all designations of Austrian wine

To digitally record and present all the origins of Austrian wines in the same perfect and clear way was the motivation for the Austrian Wine Marketing Board (Austrian Wine) to start with the project in 2018. In June 2021 the results were presented to the public in an online viewer showing all the designations of Austrian wine, available at https://austrianvineyards.com in a largely barrier-free manner. The online viewer provides tailored individual maps fitted to the respective zoom level. The smallest unit of wine-origins in Austria is called Ried and is displayed in a plot-specific manner highlighting areas under vine. Information on the Ried include administrative district, winegrowing municipality, cadastral municipality, large collective vineyard site, specific winegrowing region, generic winegrowing region, winegrowing area and, in many cases, an illustrative picture. Complementary data on the size, elevation (minimum-maximum), orientation (in 8 sectors plus flat) and gradient (minimum, maximum, average) are based on the area under vine according to the EU’s Integrated Administration and Control System. Additional information covers climate data. The diagrams are taken from the monthly breakdown of data in the annals of the Central Institute for Meteorology and Geodynamics, Austria provide a display of values for air temperature, precipitation, and sunshine hours for the reference year and the long-term average. Seasonal aggregated data on temperature, precipitation, and sunshine hours complete the display. Short descriptions with emphasis on geology and soil, field name in historical maps, etymology of the denomination, and main planted variety complements the available information for the main designations in the online viewer. These descriptions are compiled by winegrowers, geologists, historians, and journalists. All the information and data can be extracted to a pdf-file. Printed vineyard maps are also available. Missing content regarding wine origins in Styria will be completed in winter 2021/22.

Bioclimatic shifts and land use options for Viticulture in Portugal

Land use, plays a relevant role in the climatic system. It endows means for agriculture practices thus contributing to the food supply. Since climate and land are closely intertwined through multiple interface processes, climate change may lead to significant impacts in land use. In this study, 1-km observational gridded datasets are used to assess changes in the Köppen–Geiger and Worldwide Bioclimatic (WBCS)

Legacy of land-cover changes on soil erosion and microbiology in Burgundian vineyards

Soils in vineyards are recognized as complex agrosystems whose characteristics reflect complex interactions between natural factors (lithology, climate, slope, biodiversity) and human activities. To date, most of the unknown lies in an incomplete understanding of soil ecosystems, and specifically in the microbial biodiversity even though soil microbiota is involved in many key functions, such as nutrient cycling and carbon sequestration. Soil biological properties are indicative of soil quality. Therefore, understanding how soil communities are related to soil ecosystem functioning is becoming an essential issue for soil strategy conservation. Here, we propose to assess the importance of land-cover history on the present-day microbiological and physico-chemical properties. The studied area was selected in the Burgundian vineyards (Pernand-Vergelesses, Burgundy, France) where land occupation has been reconstructed over the last 40 years. Soil samples were collected in five areas reflecting various land cover history (forest, vineyards, shifting from forest to vineyards). For each area, physico-chemical parameters (pH, C, N, P, grain size) were measured and DNA was extracted to characterize the abundance and diversity of microbial communities. The obtained results show significant differences in the five areas suggesting that present-day microbial molecular biomass and bacterial taxonomic is partly inherited from past land occupation. Over longer period of time, such study of land-uses legacies may help to better assess ecosystem recovery and the impact of management practices for a better soil quality and vineyards sustainability.

Climate change impacts: a multi-stress issue

With the aim of producing premium wines, it is admitted that moderate environmental stresses may contribute to the accumulation of compounds of interest in grapes. However the ongoing climate change, with the appearance of more limiting conditions of production is a major concern for the wine industry economic. Will it be possible to maintain the vineyards in place, to preserve the current grape varieties and how should we anticipate the adaptation measures to ensure the sustainability of vineyards? In this context, the question of the responses and adaptation of grapevine to abiotic stresses becomes a major scientific issue to tackle. An abiotic stress can be defined as the effect of a specific factor of the physico-chemical environment of the plants (temperature, availability of water and minerals, light, etc.) which reduces growth, and for a crop such as the vine, the yield, the composition of the fruits and the sustainability of the plants. Water stress is in many minds, but a systemic vision is essential for at least two reasons. The first reason is that in natural environments, a single factor is rarely limiting, and plants have to deal with a combination of constraints, as for example heat and drought, both in time and at a given time. The second reason is that plants, including grapevine, have central mechanisms of stress responses, as redox regulatory pathways, that play an important role in adaptation and survival. Here we will review the most recent studies dealing with this issue to provide a better understanding of the grapevine responses to a combination of environmental constraints and of the underlying regulatory pathways, which may be very helpful to design more adapted solutions to cope with climate change.