# How terroir shapes aromatic typicity in grapes and wines (Part II)

Cornelis van Leeuwen, Jean-Christophe Barbe, Olivier Geffroy, Mark Gowdy, Georgia Lytra, Alexandre Pons, Cécile Thibon, Stéphanie Marchand

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## To cite this version:

Cornelis van Leeuwen, Jean-Christophe Barbe, Olivier Geffroy, Mark Gowdy, Georgia Lytra, et al. How terroir shapes aromatic typicity in grapes and wines (Part II). IVES Technical Reviews vine and wine, 2023, 10.20870/IVES-TR.2023.7392. hal-04346298

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Submitted on 15 Dec 2023

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# How terroir shapes aromatic typicity in grapes and wines (Part II)

Cornelis van Leeuwen<fnref n="1" />*, Jean-Christophe Barbe<fnref n="2" />, Olivier Geffroy<fnref n="3" />, Mark Gowdy<fnref n="1" />, Georgia Lytra<fnref n="2" />, Alexandre Pons<fnref n="2" />,<fnref n="4" />, Cécile Thibon<fnref n="2" />, Stéphanie Marchand<fnref n="2" />

Over the past decades, great progress has been accomplished in the understanding of the molecular basis of aromas in grapes and wines. These aromas depend on the grapevine variety, but also on environmental factors involved in the so-called « terroir » effect. In the first part of this review, it was shown how the terroir effect can be decomposed in measurable climate and soil parameters, namely air temperature, radiation, nitrogen and water status. Their impact on aromas and wine typicity is well documented in the scientific literature. In the second part of this review, examples are provided about the terroir effect for three major red varieties (Merlot, Cabernet-Sauvignon and Syrah) and two white varieties (Sauvignon blanc and Riesling). How wine aromas can be optimized through vineyard management practices is also discussed.

## Examples of aroma profiles related to specific terroirs

Sauvignon blanc is grown under a wide range of climatic conditions and soil types. Typical cool climate Sauvignon blanc is produced in Marlborough (New Zealand), the Elgin region (South Africa) and Sancerre (France). Its aroma nuances are shaped by a delicate balance between green aromas (bell pepper induced by IBMP and boxwood by 4-MSP) and fruity aromas (grapefruit induced by 3-SH and passion fruit by 3-SHA). Examples of warm climate Sauvignon blanc can be found in California and Australia. The aroma profile of these is dominated by passion fruit or, if the region is really hot, by a lack of aromatic expression. The archetype of cool climate Sauvignon blanc is produced in the Awatere valley (a sub region of Marlborough, New Zealand). The aroma profile is dominated by green aromas (asparagus, boxtree), associated to grapefruit. Bordeaux is a major winegrowing area for Sauvignon blanc where the climate is temperate. The most expressive Sauvignon blanc is produced in the cooler parts of the Bordeaux area, on soils with medium to high water holding capacity and medium to high in nitrogen supply.

Merlot and Cabernet-Sauvignon grown in cool climates, or with low radiation, can be green, because of the presence of IBMP. An excess of IBMP is generally not appreciated, although some green aromas, like 1,8-cineole, can provide minty freshness in the aroma expression. Merlot and Cabernet-Sauvignon grown in temperate climates express fruity flavours and develop a complex ageing bouquet after a few years of bottle storage. These positive characters are induced by a wide range of compounds, including substituted esters, volatile thiols (in particular 3-SH) and DMS. Aroma expression after bottle ageing is enhanced when wines are produced by vines facing water deficits<fnref n="1" />. It has been shown that these wines contain more DMS and tabanones. Under warm climates, wines from the above mentioned varieties can express dried fruit aromas, in particular when produced from Merlot. Some of the finest wines from Cabernet-Sauvignon are produced in Margaux, Saint-Julien, Pauillac and Saint-Estèphe (Bordeaux, France). In the Bordeaux area, Cabernet-Sauvignon ripens late in the season, when temperatures are decreasing, eliminating any possible risk of dried fruit aromas. The gravel soils of these appellations induce an interesting combination of moderate to severe water deficit and

unlimited nitrogen supply to the vines. This combination of cool climate, water deficit, and unlimited nitrogen can shape beautiful ageing bouquets.

Syrah can express different aromatic identities depending on the climate. In cool climate vineyards, such as those from the northern Rhone valley in France, the Victoria's Grampians region in Australia, or the Hawke's Bay area in New Zealand, Syrah expresses very intense peppery aromas, induced by the presence of (1)-rotundone. In warmer climates (i.e., unirrigated vineyards in the coastal parts of the Languedoc area or southern Rhone valley in France, Barossa valley in Australia), Syrah is rather marked by the expression of ripe and dried fruit, and black olive aromas. DMS has been identified as a major contributor to these notes.

The typicity of Riesling wines is shaped by various aromatic nuances, which reflect growing conditions, in particular temperature and vine water status. Typical cool climate Riesling wines, as grown in Europe (e.g., Germany, Alsace, Austria), are marked by the fruity aromas induced by volatile thiols, among other compounds, although this expression may change with increasing temperatures. Bottle aged bouquet, especially in Riesling wines from warmer climates, like Australia or South Africa, but also from United States or Canada, contains more kerosene-like aromas as a result of the presence of TDN. When Riesling is grown under high radiation and water deficits, the presence of ortho aminoacetophenone (AAP) can lead to atypical ageing, in particular when vine nitrogen status is low.

## Managing terroir-induced aroma expression in the vineyard

Terroir factors (temperature, radiation, water, nitrogen) induce specific aromatic typicities. The choice of plant material and vineyard operations can, however, modulate this expression. The excessive presence of green aromas is generally not appreciated in red wines. They are often the result of low temperatures during grape ripening, low light intensity, unlimited water supply and/or unlimited nitrogen supply. The presence of green flavours can be reduced by planting early ripening varieties (Merlot instead of Cabernet-Sauvignon). Another option is reducing nitrogen availability by planting cover crop or increasing exposure to light by leaf removal (which will also

<footnote n="1">¹ EGFV, Univ. Bordeaux, Bordeaux Sciences Agro, INRAE, ISV, F-33882 Villenave d'Ornon, France</footnote>

<footnote n="2">² Univ. Bordeaux, Bordeaux INP, Bordeaux Sciences Agro, UMR 1366 OENOLOGIE, ISV, F-33140 Villenave d'Ornon, France</footnote>

<footnote n="3">³ PPGV, Université de Toulouse, INP-PURPAN, 75 voie du TOEC, F-31076 Toulouse Cedex 3, France</footnote>

<footnote n="4">⁴ Tonnellerie Seguin-Moreau, ZI Merpins, 16103 Cognac</footnote>
<table><caption>TABLE 1. The effects of varietal choices and management practices to modulate aroma expression linked to terroir. References can be found in van Leeuwen et al., 2020⁶.</caption><thead><tr><th>Management practices and plant material choices</th><th>Impact on green aromas (IBMP)</th><th>Impact on boxtree, grapefruit and passion fruit nuances (volatile thiols)</th><th>Impact on cooked fruit and oxidized prune aromas</th><th>Impact on atypical ageing in white wine (AAP)</th></tr></thead><tbody><tr><td>Leaf removal</td><td>Practice early leaf removal in cool and wet climates to reduce green aromas</td><td></td><td>Limit leaf removal to avoid excessive bunch exposure in warm climates which favours cooked fruit and oxidized prune aromas</td><td>Excessive exposure of bunches to direct sunlight can favour atypical ageing of white wines, in particular under warm and sunny climates</td></tr><tr><td>Training systems</td><td>Use training systems that favour open canopies (VSP, Smart-Dyson, Lyre trellis) in cool and wet climates</td><td></td><td>Use training systems that favour some amount of bunch shading (globlet bushvines, pergola, VSP without leaf removal) to limit cooked fruit and oxidized prune aromas in warm climates</td><td></td></tr><tr><td>Water management</td><td>Water deficits reduce green aromas in cool climates. Full irrigation favours excessive vigour which may lead to green aromas in cool and warm climates through excessive bunch shading and late shoot growth cessation</td><td>Moderate water deficit favours the development of volatile thiol precursors in grapes, while severe water deficit is detrimental</td><td>Avoid late-season severe water deficits in warm climates, which may lead to berry shrivel and enhance cooked fruit and oxidized prune aromas</td><td>Water deficit increases the risk of atypical ageing in white wine</td></tr><tr><td>Nitrogen fertilisation</td><td>Excessive nitrogen fertilisation leads to high vigour and favours green aromas through bunch shading, in cool and warm climates</td><td>Increasing vine nitrogen status through fertilisation enhances the synthesis of volatile thiol precursors in grapes and promotes the production of glutathion, a natural preservative of volatile thiols in wines</td><td>Nitrogen deficiency leads to low vigour and excessive bunch exposure that favours cooked fruit and oxidized prune aromas in warm climates</td><td>Nitrogen fertilisation limits the risk of atypical ageing in white wine</td></tr><tr><td>Cover cropping</td><td>Cover cropping reduces vigour, improves bunch exposure and limits green aromas in cool and warm climates</td><td>Cover cropping reduces vine nitrogen status (except when legumes are involved), which limits the synthesis of volatile thiol precursors in grapes</td><td>Avoid low vine nitrogen status through competitive cover cropping in warm climates, because it enhances the development of cooked fruit and oxidized prune aromas through excessive bunch exposure</td><td>Avoid low vine nitrogen status through competitive cover cropping in warm climates, because it enhances the development of atypical ageing in white wine through excessive bunch exposure</td></tr><tr><td>Variety choices</td><td>Use early ripening varieties in cool climates to avoid green aromas</td><td>Levels of volatile thiol precursors are variety dependant. Sauvignon blanc and Riesling (among others) contain high levels</td><td>Use late ripening varieties in warm climates to limit development of cooked fruit and oxidized prune aromas</td><td>Riesling is particularly prone to the development of aminoacetophenone (AAP)</td></tr><tr><td>Rootstock choices</td><td>Use low to medium vigour rootstocks in cool and wet climates to limit green aromas through improved bunch exposure</td><td></td><td>Use medium to high vigour rootstocks in warm climates to reduce bunch exposure and delay maturity in order to limit cooked fruit and oxidized prune aromas</td><td>Any rootstock limiting water stress and inducing moderately high vigour limits the risk of atypical ageing</td></tr></tbody></table>

increase the temperature in the bunch zone). Under warm climates there is a risk to produce red wines that are excessively marked by overriding and "trivial" dried fruit aromas, which reduces freshness and aromatic complexity. These can be limited by planting later ripening varieties (Cabernet-Sauvignon instead of Merlot). Other options are earlier harvest dates or increased vegetative expression and vigour to expose bunches to less direct sunlight. In Sauvignon blanc, grapefruit expression can easily be enhanced by nitrogen fertilization (when soil N supply is limited), either through foliar application or additions on the soil²,³. In warm climates, or on soils inducing moderate to severe water deficits, red varieties should be preferred over Sauvignon blanc or other early ripening white varieties for the production of high-quality wines. Berry temperature and light can be manipulated through canopy management and leaf removal. The effects of varietal choices and management practices to modulate aroma expression linked to terroir are summarized in table 1. Harvest date also has an important impact on wine typicity⁴. An extensive review on the effect of management practices on aroma compounds in grapes and wines can be found in Alem et al., 2019⁵.

## Conclusion

Wine typicity in relation to terroir is largely shaped by odorous compounds. Over the past decades, a wide body of literature is published on the molecular basis of wine aromas. Many of these studies relate cultivar specific aroma profiles and how these are influenced by environmental factors and management practices. Major factors of terroir expression are air temperature, radiation, water supply to the vines and vine nitrogen status. Reviewing the effect of these factors on aroma compounds provides a better understanding of how terroir shapes aromatic typicities. Based on this knowledge,

aroma expression can be optimized through varietal choices or management practices. ■

Sourced from the research article: "Recent advancements in understanding the terroir effect on aromas in grapes and wines" (OENO One, 2020).

1 Picard, M., van Leeuwen, C., Guyon, F., Gaillard, L., de Revel, G., & Marchand, S. (2017). Vine water deficit impacts aging bouquet in fine red Bordeaux wine. Frontiers in Chemistry, 5, 56. https://doi.org/10.3389/fchem.2017.00056

2 Choné, X., Lavigne-Cruège, V., Tominaga, T., van Leeuwen, C., Castagnède, C., Saucier, C., & Dubourdieu, D. (2006). Effect of vine nitrogen status on grape aromatic potential: flavor precursors (S-cysteine conjugates), glutathione and phenolic content in Vitis vinifera L. Cv Sauvignon blanc grape juice. Journal International des Sciences de la Vigne et du Vin, 40(1), 1-6. https://doi.org/10.20870/oeno-one.2006.40.1.880

3 Lacroux, F., Trégoat, O., van Leeuwen, C., Pons, A., Tominaga, T., Lavigne-Cruège, V., & Dubourdieu, D. (2008). Effect of foliar nitrogen and sulphur application on aromatic expression of Vitis vinifera L. cv. Sauvignon blanc. Journal International des Sciences de la Vigne et du Vin, 42(3), 125-132. https://doi.org/10.20870/oeno-one.2008.42.3.816

4 Antalick, G., Šuklje, K., Blackman, J. W., Schmidtke, L. M., & Deloire, A. (2021). Performing sequential harvests based on berry sugar accumulation (mg/berry) to obtain specific wine sensory profiles. OENO One, 55(2), 131-146. https://doi.org/10.20870/oeno-one.2021.55.2.4527

5 Alem, H., Rigou, P., Schneider, R., Ojeda, H., & Torregrosa, L. (2019). Impact of agronomic practices on grape aroma composition: a review. Journal of the Science of Food and Agriculture, 99(3), 975-985. https://doi.org/10.1002/jsfa.9327

6 van Leeuwen, C., Barbe, J. C., Darriet, P., Geffroy, O., Gomès, E., Guillaumie, S., Helwi, P., Laboyrie, J., Lytra, G., Le Menn, N., Marchand, S., Picard., M., Pons., A., Schüttler A. & Thibon, C. (2020). Recent advancements in understanding the terroir effect on aromas in grapes and wines. OENO One, 54(4), 985-1006. https://doi.org/10.20870/oeno-one.2020.54.4.3983

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