Macrowine 2021
IVES 9 IVES Conference Series 9 Long-term sensorial and compositional effects of copper fining on the wine containing ‘reductive’ and ‘tropical’ volatile sulfur compounds

Long-term sensorial and compositional effects of copper fining on the wine containing ‘reductive’ and ‘tropical’ volatile sulfur compounds

Abstract

The aim of this study was to investigate long-term sensorial and compositional effects of copper addition to the white wine naturally high in varietal thiol levels, with added volatile sulfur compounds [hydrogen sulfide (H2S) and methanethiol (MeSH)]. The novelty of this study lies in the inclusion of sensory analysis at each time point by using Check-All-That-Apply and Descriptive Analysis methods to evaluate the sensory interaction between ‘reductive’ thiols and tropical thiols after copper fining. The Chenin Blanc wine was used as control (base) wine to which combinations of 40 µg/L H2S and 20 µg/L of MeSH were added, followed by an addition of 0,3 mg/L of copper to selected samples. The wine samples were stored for 24 hours, 6 weeks and 1 year. At each time point chemical analysis of varietal thiols, volatile sulfur compounds and copper levels were performed. The chemical results after 1 year of wine storage, showed a significant increase in the levels of varietal thiol 3-sulfanylhexanol (3-SH) and a decrease of 3-sulfanylhexyl acetate (3-SHA) concentration levels. However, a significant loss of 3-SH occurred in all the copper treated wines after 1 year of storage. On the other hand, the decrease of 3-SHA levels over time was less influenced by copper treatment, but rather due to acid hydrolyses and a subsequent increase in 3-SH (Makhotkina & Kilmartin, 2012). The presence of copper seem to further increase levels of bound- H2S in wine samples, which after 1 year of storage amounted to more than 25 µg/L. Chemical analysis of MeSH showed the significant increase in free and bound MeSH after 1 year of storage in wine samples spiked with MeSH. However, the addition of copper to the MeSH-spiked samples resulted in significant decrease of free and bound MeSH. The most significant sensory impact of the addition of H2S and MeSH to control wine was the suppression effect on “fruitiness” of wine after 24 hours which after 6-weeks and 1-year wine storage period decreased, potentially due to wine matrix absorption of H2S and MeSH (Nikolantonaki & Waterhouse, 2012). Sensory results after 1 year of wine storage showed that “guava”, a “tropical” attribute, was not suppressed with the addition of H2S and MeSH and low doses of “reductive” aromas deriving from H2S and MeSH in wine might even contributed to its sensory perception. Copper additions mainly decreased the perception of “guava” after 1 year. In contrast, the “passionfruit”, also a “tropical” attribute, was slightly suppressed when H2S and MeSH were present. The perception of the ester-derived attributes namely “peach” and “banana” increased in the samples containing copper after 1 year of storage, suggesting that a decrease of the 3-SH varietal thiol due to copper addition may enhance the perception of ester-derived aromas in wine.

DOI:

Publication date: September 14, 2021

Issue: Macrowine 2021

Type: Article

Authors

Matija Lesković

*South African Grape and Wine Research Institute/Department Viticulture and Oenology, University of Stellenbosch, Private Bag X1, Matieland (Stellenbosch) 7602, South Africa,Marlize BEKKER † Jeanne BRAND * Allie KULCSAR † Wessel DU TOIT * *South African Grape and Wine Research Institute/Department Viticulture and Oenology, University of Stellenbosch, Private Bag X1, Matieland (Stellenbosch) 7602, South Africa † The Australian Wine Research Institute, P.O. Box 197, Glen Osmond, South Australia, 5064.

Contact the author

Keywords

varietal thiols, volatile sulfur compounds, wine copper fining, ‘reductive’ and ‘tropical’ volatile sulfur compounds, copper fining and wine storage, wine sensory analysis

Citation

Related articles…

Analysis of some environmental factors and cultural practices that affect the production and quality of the Manto Negro, Callet and Prensal Blanc varieties

45 non irrigated vineyards distributed in the DO (Denomination) Pla i Llevant de Mallorca and the DO Binissalem Mallorca were used to investigate the characteristics of production and quality and their relationships certain environmental factors and cultural practices. The grape varieties investigated are autochthonous to the island of Mallorca, Manto Negro and Callet as red and Prensal Blanc as white. All plants were measured for four consecutive years in the main production and quality parameters. Among the environmental factors, the type of soil has been studied, more specifically its water retention capacity, the planting density, the age of the vineyard and the level of viral infection. The presence or absence of virus seems to have no effect on any component studied in the varieties studied. For the white variety Prensal Blanc age is negatively correlated with production and the number of bunches, nevertheless it does not cause any effect on the required quality parameters. However, for the red varieties Callet and Manto Negro, the age of the plantation is the variable that best correlates with the quality parameters, therefore the old vines should be the object of preservation by the viticulturists and winemakers in order to guarantee its contribution to the quality of the wines made with these varieties.

Spatiotemporal patterns of chemical attributes in Vitis vinifera L. cv. Cabernet Sauvignon vineyards in Central California

Spatial variability of vine productivity in winegrapes is important to characterise as both yield and quality are relevant for the production of different wine styles and products. The objectives were to understand how patterns of variability of Cabernet Sauvignon fruit composition changed over time and space, how these patterns could be characterised with indirect measurements, and how spatial patterns of the variation in fruit compositional attributes can aid in improving management. Prior to the 2017 vintage, 125 data vines were distributed across each of four vineyards in the Lodi American Viticultural Area (AVA) of California. Each data vine was sampled at commercial harvest in 2017, 2018, and 2019. Yield components and fruit composition were measured at harvest for each data vine, and maps of yield and fruit composition were produced for eight ‘objective measures of fruit quality’: total anthocyanins, polymeric tannins, quercetin glycosides, malic acid, yeast assimilable nitrogen, β-damascenone, C6 alcohols and aldehydes, and 3-isobutyl-2-methoxypyrazine. Patterns of variation in anthocyanins and phenolic compounds were found to be most stable over time. Given this relative stability, management decisions focused on fruit quality could be based on zonal descriptions of anthocyanins or phenolics to increase profitability in some vineyards. In each vineyard, dormant season pruning weights and soil cores were collected at each location, elevation and soil apparent electrical conductivity surveys were completed, and remotely sensed imagery was captured by fixed wing aircraft and two satellite platforms at major phenological stages. The data collected were used to develop relationships among biophysical data, soil, imagery, and fruit composition. The standardised and aggregated samples from four vineyards over three seasons were included in the estimation of ‘common variograms’ to assess how this technique could aid growers in producing geostatistically rigorous maps of fruit composition variability without cumbersome, single season sampling efforts.

A predictive model of spatial Eca variability in the vineyard to support the monitoring of plant status

[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"...

Mesoclimate impact on Tannat in the Atlantic terroir of Uruguay

The study of climate is relevant as an element conditioning the typicity of a product, its quality and sustainability over the years. The grapevine development and growth and the final grape and wine composition are closely related to temperature, while climate components vary at mesoscale according to topography and/or proximity to large bodies of water. The objective of this work is to assess the mesoclimate of the Atlantic region of Uruguay and to determine the effect of topography and the ocean on temperature and consequently on Tannat grapevine behavior.

20-Year-Old data set: scion x rootstock x climate, relationships. Effects on phenology and sugar dynamics

Global warming is one of the biggest environmental, social, and economic threats. In the Douro Valley, change to the climate are expected in the coming years, namely an increase in average temperature and a decrease in annual precipitation. Since vine cultivation is extremely vulnerable and influenced by the climate, these changes are likely to have negative effects on the production and quality of wine.
Adaptation is a major challenge facing the viticulture sector where the choice of plant material plays an important role, particularly the rootstock as it is a driver for adaptation with a wide range of effects, the most important being phylloxera, nematode and salt, tolerance to drought and a complex set of interactions in the grafted plant.
In an experimental vineyard, established in the Douro Region in 1997, with four randomized blocs, with five varieties, Touriga Nacional, Tinta Barroca, Touriga Franca and Tinta Roriz, grafted in four rootstocks, Rupestris du Lot, R110, 196-17C, R99 and 1103P, data was collected consecutively over 20 years (2001-2020). Phenological observations were made two to three times a week, following established criteria, to determine the average dates of budbreak, flowering and veraison. During maturation, weekly berry samples were taken to study the dynamics of sugar accumulation, amongst other parameters. Climate data was collected from a weather station located near the vineyard parcel, with data classified through several climatic indices.
The results achieved show a very low coefficient of variations in the average date of the phenophases and an important contribution from the rootstock in the dynamic of the phenology, allowing a delay in the cycle of up to10-12 days for the different combinations. The Principal Component Analysis performed, evaluating trends in the physical-chemical parameters, highlighted the effect of the climate and rootstock on fruit quality by grape varieties.