IVAS 2022 banner
IVES 9 IVES Conference Series 9 IVAS 9 IVAS 2022 9 Significance of factors making Riesling an iconic grape variety

Significance of factors making Riesling an iconic grape variety

Abstract

Riesling is the iconic grape variety of Germany and accounts for 23% of the German viticulture acreage, which comprises 45% of the worldwide Riesling plantings. Riesling wines offer a wide array of styles from crisp sparkling wines to highly concentrated and sweet Trockenbeerenauslese or Icewines. However, its thin berry skin makes Riesling more vulnerable to detrimental environmental threats than other white wine varieties.

Trying to adapt Riesling to climate change we investigate how to mitigate premature Botrytis infections, the loss of quality and yield due to sunburn or increasing levels of TDN, which causes the unique petrol off-flavor. Weather variation from year to year necessitates an active acidity management, either diminishing acidity by skin maceration or use of lactic acid bacteria but also more recently lowering pH by ion exchange resins or malic acid producing yeast. A strong focus is to enhance intensity and diversity of Riesling aroma by viticultural and oenological measures, which are controlled by sophisticated chemical analysis including a measure of odorless precursors.

 Riesling is a highly transparent variety in respect to terroir, deviating strongly in odor and taste due to different bed rocks and soil types, micro climates and inclination of individual vineyards. Applying comprehensive stable isotope dilution analysis of volatiles and sensory evaluation we could demonstrate not only the sensory relevance of terroir, but also how stable these patterns were over five vintages and even individual winemaking measures. Using next generation gen- sequencing techniques to study spontaneous fermentations, we could also reveal the significant impact of site specific microbiomes.

 Riesling wines are highly acclaimed for their longevity due to their exciting balance of acidity and sweetness. Re-tasting terroir defined Riesling wines again after four years revealed the expected modification in sensory terms due to aging, but prove that the general differences among the specific terroir expressions were conserved through the maturation process.

 Many of these scientific puzzle pieces were successfully implemented by the Riesling producers over the last two decades and they succeeded to improve Riesling wines in each of its multitude of stylistic facets. However, it will be a challenge to preserve their unique and diverse characters in the course of progressive climate change

DOI:

Publication date: June 22, 2022

Issue: IVAS 2022

Type: Article

Authors

Ulrich Fischer¹*
¹Institute for Viticulture and Oenology, DLR Rheinpfalz, Breitenweg 71, 67435 Neustadt, Germany

Contact the author

Keywords

Riesling, aroma compounds and precursors, sensory evaluation, terroir, acidity management, ageing of wine

Tags

IVAS 2022 | IVES Conference Series

Citation

Related articles…

Influenza del sito di coltivazione nella espressione aromatica del Moscato liquoroso di Pantelleria

ln 1997, twenty six cultivation sites of cv. Muscat of Alexandria different for pedological conditions, altitude and exposition were selected through ail Pantelleria isle. ln each site, described and classified according to USDA Soil Taxonony and FAO Soil Classification methods, grapes, collected at technological ripening, were microvinificated, following a standard procedure which allowed to obtain the naturally sweet wine DOC Moscato di Pantelleria. Wines, five months after vinification, were analysed by gaschromatography.

Influence of cork density upon cork stopper resiliency after opening a sparkling wine bottle

After Champagne popping, the first consumer’s observation is the shape of the cork stopper. Consumers expect a “mushroom shape”. Nevertheless, we sometimes observe a “barrel” shape due to inappropriate cork’s elastic properties. The aim of this study was to follow the loss of cork stopper resiliency during 26 months according to the density (d) of the cork in contact with the wine. 1680 disks were weighed + measured and divided in 6 density classes: High (H1 d= 0,19 g/cm3 – H2 d= 0,21 g/cm3), Medium (M, not studied) and Low (L1 d= 0,13 g/cm3 – L2 d= 0,14 g/cm3). Then, 138 technical cork stoppers were produced for each of the 4 studied groups. These corks consisted of an agglomerated natural cork granule body to which two natural cork disks were glued. A total of 552 bottles of sparkling wine were closed with these corks and open after 13, 19 and 26 months to follow cork resiliencies. Wine bottles were stored horizontally; thus, the external natural cork disks were in contact to the wine. During the 26 months of the study, highly significant differences (ANOVA) were observed between the resiliencies of H-corks and those of L-corks, whatever the time studied. The diameters of the L-corks were statistically higher than those of the H-corks. No significant differences were observed between L1 and L2 corks. At the opposite, differences were noted between H1 and H2 at 19 and 26 months. This could be explained by the heterogeneity of the resiliency that was higher for H-corks than for L-corks. Finally, the corks were visually (12 judges) divided in 3 classes corresponding to high (expected mushroom shape, i.e high resiliency), medium (irregular shape of the disk in contact with the wine and/or low premature deterioration of the expected resiliency) and low qualities (barrel shape = premature deterioration of the resiliency). The corks were also divided in 3 categories corresponding to 0-33%, 34-66% and 67-100% resiliency. A strong correlation was noted between the visual and the instrumental categorizations. This study strongly evidenced 1) the importance of the cork density on the cork stopper behaviour when opening the bottle and 2) the interest of an instrumental approach reflecting the consumer’s perception.

Symbiotic microorganisms application in vineyards: impacts on grapevine performance and microbiome

Microorganism-based inoculants have been suggested as a viable solution to mitigate the adverse effects of climate change on viticulture. However, the actual effectiveness of these inoculants when applied under field conditions remains a challenge, and their effects on the existing soil microbiota are still uncertain. This study investigates the impact of arbuscular mycorrhizal fungi inoculation on grapevine performance and microbiome. The study was conducted in a vineyard of Callet cultivar in Binissalem, Mallorca, Spain. Two different treatments were applied: control and inoculation with commercial mycorrhizae complex of Rhizoglomus irregulare applied to plants through irrigation.

YEAST-PRODUCED VOLATILES IN GRAPE BASED SYSTEM MODEL ACTING AS ANTIFUNGAL BIOAGENTS AGAINST PHYTOPATHOGEN BOTRYTIS CINEREA

Botrytis cinerea Pers., the causal agent of grey mould disease, is responsible for substantial economic losses, as it causes reduction of grape and wine quality and quantity. Exploitation of antagonistic yeasts is a promising strategy for controlling grey mould incidence and limiting the usage of synthetic fungicides. In our previous studies, 119 different indigenous yeasts were screened for putative multidimensional modes of action against filamentous fungus B. cinerea [1]. The most promissing biocontrol yeast was Pichia guilliermondii ZIM624, which exhibited several anatagonistic traits (production of cell wall degrading enzymes, chitinase and β-1,3-glucanase; demonstration of in vitro inhibitory effect on B. cinerea mycelia radial growth; production of antifungal volatiles, assimilation of a broad diversity of carbon sources, contributing to its competitivnes in inhabiting grapes in nature).

An exploration of South Tyrolean Pinot blanc wines and their quality potential in vineyard sites across a range of altitudes

Aim: Pinot Blanc is the third most planted white wine grape in northern Italy’s region of South Tyrol, where small-scale viticultural production permits the examination of the wine’s diverse expressive potential in a small area across a wide range of climatic variables. This study aimed to explore the qualitative potential of Pinot Blanc across a range of climatic variation leading to site-specific terroir expression in a cool climate region.