OENO IVAS 2019 banner
IVES 9 IVES Conference Series 9 Optimizing the use of bentonite for better control of haze formation In white and rosé wines

Optimizing the use of bentonite for better control of haze formation In white and rosé wines

Abstract

In winemaking, the appearance of turbidity in white and wine is a serious visual defect, which lowers significantly its commercial value. A major cause of the formation of turbidity in wine is attributed to the presence of temperature-sensitive proteins. The proteins undergo slow conformational changes, leading to aggregation and flocculation phenomena. The process can be accelerated by exposure of wine to high temperatures during transportation or storage. In recent years heat-unstable proteins in white wine were identified as grape class IV chitinases, β-glucanases and a fraction of thaumatin-like proteins. Although proteins play a central role in the formation of turbidity, other components present in wine such as polyphenols, sulfate anion, polysaccharides as well as ionic strength and pH value play an important role in these phenomenon.

 The lack of reliable tests assessing the risk of protein clouding during bottle storage is a recurring problem of winemakers. Currently used test assessing haze potential involves heating which often causes overdosing of fining agent. Despite the large progress in the white wine research and substantial development of the analytical methods applied the phenomenon of white wine haze formation remains unrevealed. The traditional treatment used to stabilize wine includes the addition of bentonite, which is certainly effective but due to its non-specific binding results in a considerable decrease in aroma compounds and therefore the quality of the wine. Thus, a strong need to establish a more selective and economically justified method of wine stabilization, which will preserve the aroma compounds in white and rosé wine, is undeniable.

 

This study aimed at the development of more reliable haze potential tests and more specific treatments for wine. To achieve this objective the knowledge the protein binding properties of different types of commercial bentonite have been analyzed, including the following: elemental analysis, surface charge density, swell index, external and internal specific surface area. The effect of quality of water used for hydration and wine pH on the swelling properties of bentonite have been also investigated. The proteins and polyphenols bound by different types of bentonite as well as the quality of the obtained wine (aroma compounds) have been identified using the above-mentioned methods and compared during three harvest periods. Finally, we have established the possibility of using bentonite alternatively on must with the development of a specific test to establish the dose of treatment.

DOI:

Publication date: June 10, 2020

Issue: OENO IVAS 2019

Type: Article

Authors

Benoit Bach, Anne-Claire Silvestri, Jean-Christophe Perret, Marilyn Cléroux, Marie Blackford, Agnieszka Kosinska Cagnazzo, Marc Mathieu, Wilfried Andlauer

Changins, viticulture and enology, University of Applied Sciences and Arts Western Switzerland, Route de Duillier 50, 1260 Nyon, Switzerland
Institute of Life Technologies, University of Applied Sciences and Arts Western Switzerland Valais, Route du Rawyl 64, 1950 Sion, Switzerland

Contact the author

Keywords

wine, protein, haze, bentonite

Tags

IVES Conference Series | OENO IVAS 2019

Citation

Related articles…

Biodiversity in the vineyard agroecosystem: exploring systemic approaches

Biodiversity conservation and restoration are essential for guarantee the provision of ecosystem services associated to vineyard agroecosystem such as climate regulation trough carbon sequestration and control of pests and diseases. Most of published research dealing with the complexity of the vineyard agroecosystems emphasizes the necessity of innovative approaches, including the integration of information at different temporal and spatial scales and development of systemic analysis based on modelling. A biodiversity survey was conducted in the Franciacorta wine-growing area (Lombardy, Italy), one of the most important Italian wine-growing regions for sparkling wine production, considering a portion of the territory of 112 ha. The area was divided into several Environmental Units (EUs), defined as a whole vineyard or portion of vineyard homogenous in terms of four agronomic characteristics: planting year, planting density, cultivar, and training system. In each EU a set of compartments was identified and characterised by specific variables. The compartments are meteorology, morphology (altitude, slope, aspect, row orientation, and solar irradiance), ecological infrastructures and management. The landscape surrounding EU was also characterised in terms of land-use in a buffer zone of 500 m. For each component a specific methodology was identified and applied. Different statistical approaches were used to evaluate the method to integrate the information related to different compartments within the EU and related to the buffer zone. These approaches were also preliminarily evaluated for their ability to describe the contribution of biodiversity and landscape components to ecosystem services. This methodological exploration provides useful indication for the development of a fully systemic approach to structural and functional biodiversity in vineyard agroecosystems, contributing to promote a multifunctional perspective for the all wine-growing sector.

Rapid damage assessment and grapevine recovery after fire

There is increasing scientific consensus that climate changeis the underlying cause of the prolonged dry and hot conditions that have increased the risk of extreme fire weather in many countries around the world. In December 2019, a bushfire event occurred in the Adelaide Hills, South Australia where 25,000 hectares were burnt and in vineyards and surrounding areas various degrees of scorching and infrastructure damage occurred. The ability to coordinate and plan recovery after a fire event relies on robust and timely data. The current practice for measuring the scale and distribution of fire damage is to walk or drive the vineyard and score individual vines based on visual observation. The process is time consuming, subjective, or semi-quantitative at best. After the December 2019 fires, it took many months to access properties and estimate the area of vineyard damaged. This study compares the rapid assessment and mapping of fire damage using high-resolution satellite imagery with more traditional ground based measures. Satellite imagery tracking vineyard recovery in the season following the bushfire is being correlated to field assessments of vineyard productivity such as canopy health and development, fertility and carbohydrate storage. Canopy health in the seasons following the fires correlated to the severity of the initial fire damage. Severely damaged vines had reduced canopy growth, were infertile or had very low fertility as well as lower carbohydrate levels in buds and canes during dormancy, which reduced productivity in the seasons following the bushfire event. In contrast, vines that received minor damage were able to recover within 1-2 years. Tools that rapidly and affordably capture the extent and severity of damage over large vineyard area will allow producers, government and industry bodies to manage decisions in relation to fire recovery planning, coordination and delivery, improving the efficiency and effectiveness of their response.

Local adaptation tools to ensure the viticultural sustainability in a changing climate

[lwp_divi_breadcrumbs home_text="IVES" use_before_icon="on" before_icon="||divi||400" module_id="publication-ariane" _builder_version="4.19.4" _module_preset="default" module_text_align="center" module_font_size="16px" text_orientation="center"...

Understanding graft union formation by using metabolomic and transcriptomic approaches during the first days after grafting in grapevine

Since the arrival of Phyloxera (Daktulosphaira vitifolia) in Europe at the end of the 19th century, grafting has become essential to cultivate Vitis vinifera. Today, grafting provides not only resistance to this aphid, but it used to adapt the cultivars according to the type of soil, environment, or grape production requirements by using a panel of rootstocks. As part of vineyard decline, it is often mentioned the importance of producing quality grafted grapevine to improve vineyard longevity, but, to our knowledge, no study has been able to demonstrate that grafting has a role in this context. However, some scion/rootstock combinations are considered as incompatible due to poor graft union formation and subsequently high plant mortality soon after grafting. In a context of climate change where the creation of new cultivars and rootstocks is at the centre of research, the ability of new cultivars to be grafted is therefore essential. The early identification of graft incompatibility could allow the selection of non-viable plants before planting and would have a beneficial impact on research and development in the nursery sector. For this reason, our studies have focused on the identification of metabolic and transcriptomic markers of poor grafting success during the first days/week after grafting; we have identified some correlations between some specialized metabolites, especially stilbenes, and grafting success, as well as an accumulation of some amino acids in the incompatible combination. The study of the metabolome and the transcriptome allowed us to understand and characterise the processes involved during graft union formation.

Green berries on Gewürztraminer (Vitis vinifera L.) in South Tyrol (Italy)

The grape variety Gewürztraminer is known to be affected by two physiological disorders namely berry shrivel and bunch stem necrosis. During the season 2014 we noticed a new symptomatology type of ripening disorder on the variety. The new symptom showed not all berries fallowing the normal maturation stages, but single berries remaining at a soft but green stage till harvest. The broad distribution of these so called “green berries” symptoms in different production sites of our region, caused huge damage due to the difficulty of eliminating single berries per bunch before harvesting. Therefore, the Research Centre Laimburg began to investigate the reasons and origins of this new symptom. This work shows the results of first attempts to find causes for the symptom as well as the resulting approach to mitigate symptoms. Applications of magnesium leaf fertilizer showed first promising results against this putative disorder. To study the causal effect of the green berries 30 symptomatic vineyards in 2014 have been selected for a monitoring during the season 2016. To evaluate the foliar nutrient treatment two vineyards have been selected for application of magnesium sulfate and magnesium chloride. Leaf and berry nutrient analysis, as well as the main quality parameters during ripening have been performed. As soon as “green berries” symptoms appeared, incidence and severity have been evaluated. Most of the symptomatic vineyards of the 2016 monitoring showed light to clear magnesium deficit symptoms on their foliage. Only during the seasons 2020 and 2021 “green berries” symptoms could be found in the leaf fertilizer treatment vineyards. Both seasons showed a significant effect of the magnesium treatments to reduce the incidence and severity of the symptom. It seems that the appearance of the “green berries” symptom on Gewürztraminer is correlated to a disturbed uptake of magnesium of the vines.