Terroir 2016 banner
IVES 9 IVES Conference Series 9 Terroir factors causing sensory and chemical variation in Riesling wines

Terroir factors causing sensory and chemical variation in Riesling wines

Abstract

The term “terroir”, originated in France, comprises the interaction of soil, climate, and topography with the vines of a specific variety and may be extended to the human impact due to the active choice of viticultural and oenological treatments. Although geological diversity has been described for many vineyard sites, there is only scarce scientific knowledge about how the specific soil or climatic conditions translate into specific sensory differences.

To investigate the sensory impact of terroir, a range of 25 highly diverse vineyard sites were selected in Germany. Riesling grapes were harvested from those sites during five consecutive vintages, which were either processed following a standardised winemaking protocol or according to customary winemaking in the respective wine estate. Eight to ten months after harvest, a descriptive analysis by 20 trained judges characterised the wines by one colour, 14 odor and five taste attributes.

According to sensory analysis, wine originating from different vineyard sites yielded a considerable variation, although they were in close proximity. For example, throughout five vintages wines made from Riesling grapes grown on a loamy loess soil with basalt stones were much more intense in its citrus, peach, mango and honey melon attributes than the wines produced from light colored sandstone, which was described as more sour with vegetative and mineral notes. Applying discriminant analysis, it was possible to group the five bedrock types according to their sensory properties, and identify their typical aroma attributes.

Combining sensory and site specific data, PLS analysis was able to explain 48% of the sensory variation by a combined soil/climate data set with first two dimensions. The highest coefficients of determination were obtained for the explanation of sourness-related attributes (R2 0.82 – 0.94), which correlated with precipitation during the ripening period and the gravel content of the soil. The odour of honeydew melon was related to the sum of growing degree days, calcium and clay content of the soil plant available water.
Extracted flavor compounds of the wines were also analysed by GC-MS and used to group different terroirs. Furthermore, concentration of flavor compounds could be linked as well with soil and climate data using PLS-regression as well as to link them with sensory perception. 

Overall, this research could address specifically the impact of individual versus standardized winemaking, since wines were obtained from both sources, but from identical grape material. Throughout five vintages and 24 vineyard sites, customized winemaking was superior to distinguish the different terroirs to a greater extent than standardized winemaking.
Based on the analysis of up to 105 wine samples the impact of terroir could be demonstrated on a very robust data basis. Knowledge gained on how site-specific soil and climate parameters contribute to sensory differences in the wines will be an important contribution to communicating the concept of terroir to consumers.”

DOI:

Publication date: June 24, 2020

Issue: Terroir 2016

Type: Article

Authors

Ulrich Fischer (1), Andrea Bauer (2), Stefan Koschinski (3), Sascha Wolz (1), Anette Schormann (1) and Hans-Georg Schmarr (1)

(1) Institute for Viticulture and Oenology, DLR Rheinpfalz, Breitenweg 71, 67435 Neustadt/Wstr. Germany.
(2) Department of Life Sciences, University of Applied Science, Hamburg, Germany
(3) Almsco/Markes International, Germany

Contact the author

Keywords

Terroir, wine, viticulture, Riesling, aroma compounds

Tags

IVES Conference Series | Terroir 2016

Citation

Related articles…

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.

Climate, Viticulture, and Wine … my how things have changed!

The planet is warmer than at any time in our recorded past and increasing greenhouse emissions and persistence in the climate system means that continued warming is highly likely. Climate change has already altered the basic framework of growing grapes for wine production worldwide and will likely continue to do so for years to come. The wine sector can continue to play an important role in leading the agricultural sector in addressing climate change. From developing on…

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.

Influence of weather and climatic conditions on the viticultural production in Croatia

The research includes an analysis of the impact of weather conditions on phenological development of the vine and grape quality, through monitoring of four experimental cultivars (Chardonnay, Graševina, Merlot and Plavac mali) over two production years. In each experimental vineyard, which were evenly distributed throughout the regions of Slavonia and The Croatian Danube, Croatian Uplands,

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.