effects of vineyard soil properties on the phenolic ... · karakis et al., effects of vineyard soil...

KARAKIS ET AL., EFFECTS OF VINEYARD SOIL PROPERTIES ON THE PHENOLIC COMPOSITION OF SYRAH GRAPES FROM THE WALLA WALLA VALLEY AVA, PAG. 1

WWW.INFOWINE.COM – INTERNET JOURNAL OF VITICULTURE AND ENOLOGY, 2018, N. 7/2

EFFECTS OF VINEYARD SOIL PROPERTIES ON THE PHENOLIC COMPOSITION OF SYRAH GRAPES FROM THE WALLA WALLA VALLEY AVA Snejana KARAKIS1, Barry CAMERON, Kevin POGUE 1Department of Geosciences, University of Wisconsin-Milwaukee, PO Box 413, Milwaukee, WI 53201 USA 22902 *Corresponding author: Karakis. E-mail: [email protected] Introduction

The concept of terroir has been evaluated since the 12th century, when the Cistercian monks of

Burgundy realized that the physical environment in which grapes are grown has a major influence

on the character and quality of grapes and resulting wine. The unique characteristics of a vineyard,

including factors such as the geology, soil, landscape, and climate contribute collectively to the

quality of the grapes and sensory attributes of the wine produced in that vineyard (Wilson, 1998;

Haynes, 1999; White et al., 2009).

Grape phenolic compounds, which are secondary metabolites that develop in the skin and seeds of

grapes during ripening are associated with grape and wine quality. Phenolics are also known to

provide various human health benefits due to their antioxidant and anti-inflammatory properties

(Cortell and Kennedy, 2006; Koundouras et al., 2006; Di Majo et al., 2008; Kennedy, 2008; Teixeira

et al., 2013; Anesi et al., 2015). The phenolic synthesis and accumulation in grapes and therefore

grape berry phenolic content are influenced by terroir factors, including the cultivated variety and the

physical environment conditions affecting the vine nutritional and water status (Bergqvist et al., 2001;

Cortell and Kennedy, 2006; Gómez-Míguez et al., 2006; Koundouras et al., 2006; Cohen and

Kennedy, 2010; Ubalde et al., 2010; Van Leeuwen, 2010; Teixeira et al., 2013). In particular, the

vineyard soil is a key terroir element, contributing a substantial control on the grapevine nutritional

and water status, as demonstrated by the grape quality variability at the vineyard level resulting from

soil heterogeneity (Bramley et al., 2011).

The transformations that occur in the seed and skin phenolics during grape berry maturation have a

fundamental influence on wine quality because the phenolic content of grapes ultimately influences

the balance, taste, color, consistency, and aroma of wines. Although wine phenolic compounds can

also be the product of microbial activity and oak sources, most phenolic compounds found in wine

are derived from grapes and depend on factors such as grape variety, vineyard physical

environment, vineyard management, and vinification techniques (Kennedy, 2008).

Koundouras et al. (2006) compared the phenolic composition of grape berries and associated wines

produced using the same vinification techniques over two vintages, and found that grapes with high

concentrations of phenolic compounds produce wines with high phenolic content. As wine quality is

driven by the phenolic content of grapes, the concentrations of phenolics that can be extracted into

wines are dependent on the concentrations of phenolics available in the grapes (Cortell et al., 2005);

and maximizing the grape phenolic content promotes enhanced organoleptic properties and overall

quality of wines. Thus, understanding the controls on phenolic synthesis and accumulation in

grapes, which include the vineyard soil as a basic terroir factor influencing the vine nutritional and

water status, is critical for harvest and wine making decisions.



MATERIALS AND METHODS

Study Area

The study area encompasses approximately 48,000 acres in the southeast quadrant of the Walla

Walla Valley American Viticultural Area (AVA), and includes 11 vineyards planted with syrah grapes

across different terroirs (Fig. 1).

The tumultuous geological history of the Walla Walla Valley consists of massive eruptions of the

Columbia River Basalt lavas during the Miocene (17-15 Ma); vast recurring Pleistocene glacial

outburst flooding events (Missoula floods) between 15,300 and 12,700 years ago, forming graded

rhythmites (Touchet beds); and deposition of wind-blown loess of various thicknesses (Meinert and

Bussaca, 2000; Pogue, 2009). Four different and very distinctive terroirs are found across the study

area in the Walla Walla Valley AVA.

Terroir 1 is largely encountered below elevations of 366 meters (1,200 feet), consists of loess layers

of fine wind-blown silt deposits extending two to four feet deep over Missoula flood sediments, and

is represented by Pepperbridge, Seven Hills, and Va Piano vineyards.

Terroir 2 is generally found above elevations of 366 meters (1,200 feet), consists of thick loess

deposits that can be eight to ten feet thick overlying basalt bedrock, and is characterized by Les

Collines, Leonetti Loess, and Dwelley vineyards.

Terroir 3 is typically located on steep slopes in foothills and canyons, consists of very thin loess

layers of very fine, wind-blown silt extending only a few inches over weathered basalt bedrock that

underlies the entire region, and is represented by Ferguson and South Wind vineyards.

Terroir 4 is predominantly found at the lowest elevations on the Walla Walla River and Mill Creek

floodplains, consists of cobblestone river gravels of an ancient riverbed, and is characterized by

Cayuse, SJR, and Old Stones vineyards.

Figure 1: Study area located in the southeast quadrant of the Walla Walla Valley AVA.



Soil Assessment

To minimize microscale variation flattening, collocated soil and grape samples were collected from

each study vineyard in September 2014. Soil profiles were advanced and sampled throughout the

vineyards in the study area to maximum depths of 50 centimeters below ground surface. The soil

texture was determined through grain size analysis via a Malvern Mastersizer 2000E laser diffraction

particle-size analyzer. Total major and select minor and trace element compositions were

determined on the fine fraction of the vineyard soil samples, which were powdered and fused for x-

ray fluorescence (XRF) analysis. Loss on ignition (LOI) was determined by heating 1 gram of sample

for 10 minutes in a muffle furnace at 1050 °C and calculating the mass difference. The major element

and select minor and trace element compositions were obtained from glass disks fused at 1050°C

in a Claisse M4 fluxer and analyzed using a Bruker S4 Pioneer XRF in the Department of

Geosciences, at University of Wisconsin – Milwaukee.

Grape Phenolic Panel

Grape samples were collected from each study vineyard during the September 2014 harvest. Two

to three grape clusters were collected from each vineyard, and approximately 250 grams of loose

berries were weighed, placed in sealable plastic bags, and frozen prior to being submitted for

analysis. Grape phenolic profile analyses were performed by ETS Laboratory in Saint Helena,

California by high performance liquid chromatography. The grape phenolic profile analysis includes

Brix measurements and concentrations of catechins, quercetin glycosides, tannins, total

anthocyanins, and polymeric anthocyanins.

Data and Maps

Vineyard-specific data collected during the 2014 harvest, as well as data from the Web Soil Survey

(WSS, http://websoilsurvey.nrcs.usda.gov/) managed by the USDA NRCS were utilized in this study.

Data were plotted using the geographic information system software program Esri ArcGIS Desktop

to geospatially characterize the study area vineyards. WSS soil properties were assessed utilizing

the USDA NRCS Soil Data Viewer tool built as an extension to ArcMap, which facilitates spatial

mapping of soil properties from the WSS attribute database.

Results and discussion

Vineyard Soil Properties

The vineyard soils across the study area developed on top of various types of parent materials,

ranging from loess, silty loess over calcareous lacustrine, and glacio-fluvial deposits (Terroir 1), loess

deposits (Terroir 2), loess mixed with colluvium from basalt deposits (Terroir 3) and mixed, very

gravelly alluvium deposits (Terroir 4). The vineyard soils, which consist of silt loam in Terroirs 1 and

2, very stony loam in Terroir 3, and very cobbly loam in Terroir 4, contribute different textures and

depths, affecting the available nutrients and water holding capacity of the soil. Soil drainage, ranging

from well drained soils across Terroirs 1, 2, and 3 to somewhat excessively drained soils in Terroir

4, indicates overall good draining conditions for the vines across the study area. The available water

holding capacity (AWC) and organic matter (OM) values, which are lowest in the vineyard soils from

Terroirs 3 and 4 indicate optimal viticultural conditions in these areas (Fig. 2).



Figure 2: Spatial mapping of soil properties obtained from the USDA WSS attribute database.

Based on the grain size analysis, silt sized grains dominate the textures of the soil samples collected

throughout the vineyards, with an average silt content of 76.6%, average sand content of 15.8%,

and average clay content of 7.55%. The soils plot in the silt loam and silt fields of the USDA soil

texture triangle (Fig. 3), and these textures are in general agreement with the USDA taxonomic

classification for these soils.

Figure 3: Vineyard Soils Plotted on the USDA Soil Texture Triangle.

The red symbols represent the soils of Terroirs 1, 3, and 4, which are silt loam, whereas the blue

symbols represent the soils of Terroir 2, which are silt. Soil depths range from 46 to 165 cm,

indicating that best vine conditions are represent by shallowest soil vineyards located in Terroir 3.

Among the four terroirs, the vineyard soil samples containing the highest average clay content

(8.75%) were collected from Terroir 3, which corresponds to the shallowest soil depths and highest



average elevations. The vineyard soil samples containing the highest average sand content

(21.85%) were collected from Terroir 4.

The XRF total elemental analysis conducted on the fine fraction (silt and clay) of the soil samples

indicates some variation in the chemical composition of the vineyard soils. These elemental

abundances represent the total concentrations in the soil and are indicative of the general vineyard

soil composition in terms of chemical evolution over the developmental history of the soils. Overall,

the most variability in total concentrations is noted for the following oxides: SiO2 (55.4 – 65.7%),

Fe2O3 (5.5 – 10.2%), and CaO (2.3 – 5.3%). The compositional variation of the soils is illustrated

spatially on maps depicting interpolated concentrations across the study area using Esri ArcGIS

ordinary kriging (Fig. 4).

Figure 4: Spatial mapping of vineyard soil chemical composition.

Overall, the soils with the highest SiO2 and Al2O3 and lowest TiO2, Fe2O3, CaO, and MgO

compositions correspond to the vineyards of Terroir 2, consisting of thick loess over basalt. The

soils with the lowest SiO2 and highest TiO2 and Fe2O3 content are present near the southwest part

of the study area in Terroir 4 consisting of basalt cobblestone gravels. The soils with the highest

CaO and MgO compositions also coincide with Terroir 4, and extend further into the lower half of the

study area into Terroir 3 consisting of thin loess over weathered basalt. The vineyard soils of Terroir

3 also coincide with the lowest Al2O3 content among the four terroirs. The high TiO2, MgO, and Fe2O3

content in the soils samples from Terroirs 3 and 4 are indicative of the influence of basalt, and result

from the oxidation of ferromagnesian minerals such as pyroxene, amphibole, and biotite from mafic

igneous rocks like the basalt cobblestone gravels and weathered basalt bedrock present in these

areas.



Grape Phenolic Compounds

Grape phenolic compounds are classified into non-flavonoids and flavonoids. The two most well-

known non-flavonoid classes are the hydroxycinnamates and stilbenes; and the four main classes

of flavonoids are the anthocyanins, flavonols (glycosides of quercetin, kaempferol, myricetin, and

isorhamnetin), proanthocyanidins (condensed tannins), and flavan-3-o1 monomers (catechins),

which are subunits of the proanthocyanidins (Cortell et al., 2005; Kennedy et al., 2006; Cortell and

Kennedy, 2006).

The average values of Brix measurements and concentrations of catechins, quercetin glycosides,

tannins, total anthocyanins, and polymeric anthocyanins for the four terroirs are presented on Figure

5. The highest average Brix values correspond to the grapes from Terroir 2 vineyards. Brix is a

dissolved sugar concentration measurement used to predict the potential alcohol level in wines,

using an average conversion rate of sugar into alcohol.

The highest average tannin and total anthocyanin concentrations are associated with the grapes

from Terroir 3. Tannins contribute to the body and astringency of wines, and anthocyanins are the

primary source of color in red wines. The grapes from Terroir 3 also have the lowest average

catechin concentrations, indicating best seed maturity and ripeness among the four terroirs.

The highest average quercetin glycosides and polymeric anthocyanins concentrations correspond

to the grapes from Terroir 4 vineyards. Quercetin reacts with anthocyanins and polymeric

anthocyanins are complexes of anthocyanins and tannin, both producing a more stable color through

aging, aiding in the color maintenance of red wine.

Figure 5: Average concentrations of grape phenolic compounds in the four terroirs.



Conclusion

The classes and concentrations of phenolic compounds in syrah grapes collected during the 2014

harvest were compared to the soil properties at the same location for each of the four terroirs across

the study area in the Walla Walla Valley AVA.

Based on a preliminary evaluation, the concentrations of grape phenolic compounds are a function

of the soil properties influencing the vine water status. Overall, the highest Brix values correspond

to Terroir 2 vineyards (Les Collines, Leonetti Loess, and Dwelley) which are planted in silt loam soils

that developed from loess parent materials. Terroir 2 consists of thick loess overlying basalt bedrock,

and is characterized by soils with the highest silt content, highest SiO2 and Al2O3 compositions, and

lowest O.M. % and sand content among the four terroirs.

The highest tannin and total anthocyanin along with the lowest catechin concentrations are

associated with Terroir 3 vineyards (Ferguson and Southwind), which are planted at the highest

elevations in very stony loam soils that developed from loess mixed with colluvium from basalt parent

materials. Terroir 3 consists of thin loess overlying weathered basalt bedrock, and is generally

characterized by well drained, low water holding capacity, shallow soils, with some of the highest

CaO and MgO compositions, and the lowest Al2O3 content.

The highest concentrations of quercetin and polymeric anthocyanin are associated with Terroir 4

vineyards (Cayuse, SJR, and Old Stones), which are planted in very cobbly loam soils developed

from gravelly alluvium parent materials. Terroir 4 consists of basalt cobblestone gravels and is

characterized by soils that are somewhat excessively drained, coarser textured, with low-moderate

water-holding capacity, and the highest CaO, MgO, TiO2 and Fe2O3 compositions among the four

terroirs.

Acknowledgments

The authors wish to express their sincere appreciation to the Walla Walla Valley AVA winery owners,

vineyard managers, and winemakers for their kindness and generosity in providing not only access

to their vineyards, but very enjoyable and informative terroir discussions.

LITERATURE CITED

Anesi A, Stocchero M, Dal Santo S, Commisso M, Zenoni S, Ceoldo S, Tornielli GB, Siebert TE, Herderich M,

Pezzotti M, Guzzo F., 2015. Towards a scientific interpretation of the terroir concept: plasticity of the grape

berry metabolome. BMC Plant Biol. 15:191. doi: 10.1186/s12870-015-0584-4.

Cohen, S.D. and Kennedy, J.A., (2010) Plant metabolism and the environment: Implications for managing

phenolics. Crit. Rev. Food Sci. Nutr. 50, 620–643.

Cortell, J. M.; Halbleib, M.; Gallagher, A. V.; Righetti, T.; Kennedy, J. A., 2005. Influence of vine vigor on grape

(Vitis Vinifera L. cv. Pinot noir) and wine proanthocyanidins. J. Agric. Food Chem. 53, 5798-5808.

Cortell, J. M. and Kennedy, J. A., 2006. Effect of shading on accumulation of flavonoid compounds in Vitis

Vinifera L. Pinot noir fruit and extraction in a model system. J. Agric. Food Chem. 54, 8510-8520.

Di Majo D., La Guardia M., Giammanco S, La Neve L., Giammanco M., 2008. The antioxidant capacity of red

wine in relationship with its polyphenolic constituents. Food Chem 111:45–49.



Gómez-Míguez M.J., Gómez-Míguez M., Vicario I.M., Heredia F.J., 2006. Assessment of colour and aroma in

white wines vinifications: Effects of grape maturity and soil type. Journal of food engineering 79:758–764.

Haynes, S.J., 1999. Concept of terroir and the role of geology. Geoscience Canada, 26: 190-194.

Kennedy J.A., Saucier C., and Glories Y., 2006 Grape and wine phenolics: History and perspective. Am. J.

Enol. Vitic. 3:20–21.

Kennedy, J.A., 2008. Grape and wine phenolics: Observations and recent findings. Cien.Inv. Agr. 35(2):107-

120.

Koundouras, S., Marinos, V., Gkoulioti, A., Kotseridis, Y. and van Leeuwen, C., 2006. Influence of vineyard

location and vine water status on fruit maturation of nonirrigated cv. Agiorgitiko (Vitis vinifera L.). Effects on

wine phenolic and aroma components. J. Agric. Food Chem. 54, 5077–5086.

Meinert, L.D., and Busacca, A.J., 2000. Terroirs of the Walla Walla Valley appellation, southeastern

Washington State, USA. Geoscience Canada, 27: 149-171.

Pogue K., 2009. Folds, floods, and fine wine: Geologic influences on the terroir of the Columbia basin. In:

Volcanoes to Vineyards: Geologic Field Trips through the Dynamic Landscape of the Pacific Northwest:

O'Connor, J., Dorsey, R., and Madin, I., Eds. Geological Society of America Field Guide 15. p. 1-17.

Soil Survey Staff, Natural Resources Conservation Service, United States Department of Agriculture. Web Soil

Survey. Available online at http://websoilsurvey.nrcs.usda.gov/. Accessed 10/13/2015.

Teixeira, A.; Eiras-Dias, J.; Castellarin, S.D.; Gerós, H., 2013. Berry Phenolics of Grapevine under Challenging

Environments. Int. J. Mol. Sci. 14, 18711-18739.

Ubalde, J.M., Sort, X., Zayas, A. and Poch, R.M., 2010. Effects of soil and climatic conditions on grape ripening

and wine quality of Cabernet Sauvignon. J. Wine Res. 21, 1–17.

Van Leeuwen, C., 2010. Terroir: the effect of the physical environment on vine growth, grape ripening and

wine sensory attributes. In Managing Wine Quality, Volume 1: Viticulture and wine quality, Ed. Andrew

Reynolds, p. 273-315.

White, M.A., Whalen, P., and Jones, G.V., 2009. Land and Wine, Nature Geoscience, 2: 82-84.

Wilson, J. E., 1998. Terroir: The Role of Geology, Climate and Culture in the Making of French Wines.

University of California Press. 336 p.



Abstract

Grape phenolic compounds, which are secondary metabolites that develop in grapes during ripening

are associated with grape and wine quality. The phenolic synthesis and accumulation in grapes and

the resulting grape phenolic content are influenced by terroir. In particular, the vineyard soil is a key

terroir element contributing a substantial control on the grapevine nutritional and water status; thus,

the properties of vineyard soils influence the quality of the grapes and sensory attributes of the wine

produced in that vineyard. This study presents an evaluation of the relationships between soil

characteristics (parent material, depth, texture, chemistry, water holding capacity, and organic matter)

and the classes and concentrations of phenolic compounds developed in syrah grapes from vineyards

located in the four different terroirs of Walla Walla Valley American Viticultural Area, exploring the link

between grape quality and terroir in a step toward quantifying and further deciphering the terroir effect.

Keywords: Walla Walla Valley, Terroir, Phenolic Compounds, Syrah Grapes, Soil Properties

effects of vineyard soil properties on the phenolic ... · karakis et al., effects of vineyard soil...

Documents