BRUCE ZOECKLEIN Inquiring Winemaker

Structural and textural components that impact mouthfeel interact in a palate balance relationship depicted in Finding Balance “Palate Structure and Texture Balance Components” on page 67. This somewhat over-simplified association suggests that an increase in the perception on one side of in Viognier this relationship decreases the perception of components on the other side. The converse is also true. With this in mind, it is easy to oday’s consumers expect Viog- textural balance requires an understanding understand how perception of structural nier to be well balanced with a of the , impact of manage- and texture components interrelate. symphony of integrated aromas ment and how variables influ- The sweet elements impact not simply and flavors. Balance and har- ence the integration of fruit, wood, yeast sweet taste but also, in a dry , the mony are two descriptors often and bacteria-derived aromas and flavors. perception of body or volume. These used to denote quality, while A significant volume of research has sensory features are derived mainly unpleasantT coarseness, aftertaste involving advanced our understanding of how from carbohydrates, polysaccharides, bitterness and/or excessive astringency or various viticultural practices such as crop mannoproteins, gums and alcohol. The hotnessMori_Nov05.qxt can negatively 9/19/05 impact 3:29 this imporPM Page- level,1 1 crop exposure,2,3 leaf area to crop acid elements are the result of grape- tant wine. To attain structural and ratio,4 shoot density, training systems5 and derived organic acids or acid addition. The terroir6 affect grape and wine components. phenolics include sensations derived from However, few studies have been directed the skins, seeds and stems, and they may to Viognier. The paper “Effect of also result from winemaker intrusions such Vertical Shoot-Positioned, Smart-Dyson as barrel and enological tannins. Phenolic and Geneva Double-Curtain Training compounds in Viognier can provide a Systems on Viognier Grape and Wine range of sensory features including what is Composition”7 reported that Viognier described as tannin intensity, astringency, training impacted grape and wine volatiles bitterness and dry tannins. SUPPLIERS OF QUALITY and wine aroma, flavor and mouthfeel. Integration of structure and texture With most varieties, grape aroma and components is important because VIRUS CERTIFIED flavor development is relatively linear, perceptions occur in different parts of the GRAFTED GRAPEVINES increasing at a relatively even pace near palate and, therefore, at different time the end of the ripening period. Viognier, however, undergoes an engustment (a Deadline for Custom rapid respiratory change) late in the season that creates the aroma and flavor Grafted Order characteristics associated with the variety Highlights For Spring Planting is including lychee, musk, rose, pear, apricot, peach, nectar, ginger and citrus. • While researchers have examined the January of Previous Year Engustment occurs late in the season, correlation between viticultural practices often with a relatively high potential and wine properties, few of their studies alcohol (above 14%), linking aroma and have included the winegrape Viognier. For Further Information flavor to mouthfeel. Viognier varietal character is largely the result of C13- • In this column Bruce Zoecklein analyzes & Pricing norisoprenoïds and . Yeast-derived Please Call or Write how and winemaking affect aromas are mainly from esters produced as the components of wine balance. a result of the metabolism of fatty acids 1912 Concession 4 and amino acids. Generally, these are less R.R. #2 Niagara-on-the-Lake • In high-quality Viognier, we expect to stable than grape-derived aromas. The Ontario, Canada LOS 1J0 experience sweetness, acidity and phe- Phone: 905-468-0822 relatively high alcohol in most Viognier nolic elements as a harmonious whole. Fax: 905-468-0344 can impact both varietal and fermentation aroma and flavors as well as mouthfeel.

66 & Vines FEBRUARY 2013 WINEMAKING

Palate Structure and Texture Balance Components Correlations with Volume, Body, Sweetness <——> Acid + Phenolics (tannin intensity, Volume, Body, Sweetness astringency, dry tannins, bitterness) + Alcohol + Polysaccharides and mannoproteins Volume, Body, Sweetness Acid Phenolics + Gums, like Gum Arabic • Carbohydrates • Organic acids • Skin, seed and stem phenols • Polysaccharides • Barrel phenols Alcohol, an important component to • Mannoproteins • Enological tannins Viognier, impacts wine mouthfeel being bitter- • Gums • Volatile phenols sweet and producing palate hotness.8 A high • Alcohol (above 14.5%) alcohol level may enhance negative textural characteristics including tannin roughness and bitterness. This intervals. For example, we initially taste sweet perception, thus lowering the sense highlights the importance of understanding sweetness at the front of the palate, followed of acidity and the discernment of phenols. the potential alcohol level (sugar-to-ethanol by acidity, and finally the taste of bitterness This highlights the inverse nature of the conversion) specific to each vineyard site. and tactile sensation of astringency near palate-balance relationship. It also serves Mannoproteins in the yeast cell wall the back of the palate. Yet we expect in a as a reminder of the importance of specific are bound to glucans and exist in wines high-quality, well-integrated and balanced serving temperature recommendations as polysaccharides and proteins. They are Viognier not to perceive these as separate predicated on style and essential for released from the cell wall by the action sensations, but as a harmonious whole. optimum wine enjoyment. of an enzyme (ß-1,3-glucanase) and can Palate balance is impacted by the The relative interaction of the structure impact aroma, oxygen buffering and wine quantitative and qualitative nature of and texture components of Viognier are stability.9,10 These so-called macromolecules components in the above relationship and outlined in the following gray boxes. provide a sense of sweetness as a result of wine temperature. For example, a low The plus signs (+) indicate a positive increasing the perception of volume or temperature can increase the perception correlation; negative signs (-) a negative body, thereby lowering the perception of of acidity while reducing the perception correlation, and zero (0) no association. acidity and the phenol elements.11 This is of sweet elements. Warming wine a few These generalizations follow winemaker’s one reason for the addition of glucanase degrees often reverses this by increasing the empirical observations. enzymes and/or storage sur lie.

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Finding Solutions Through Research Drs. Walker and Cousins continue to develop rootstocks resistant to and nematodes while displaying tolerance to abiotic stressors like drought and salts, with new selections from the Walker program now available to growers. Dr. Qian and others are studying the impact of closures with di erent oxygen transmission rates on aroma development with a focus on volatile sulfur compounds during post bottling aging. This work should help the industry make informed closure selections. For a wealth of useful viticulture and enology research and information, visit AVF.org, iv.ucdavis.edu, enologyaccess.org, or ngwi.org.

P.O. Box 5779, Napa, CA., 94581 • T: (707) 252-6911 • Email [email protected]. Visit our Web site at www.avf.org for information on funding and current research projects

Wines & Vines FEBRUARY 2013 67 WINEMAKING

Attaining balance with Viognier requires an understanding of the grape, impact of vineyard management and how winemaking variables influence the integration of aromas and flavors.

Newly fermented Viognier is frequently settled for 24 hours Increasing the perception of acidity usually increases the to remove gross . Subsequent racking may remove a large perception of the phenolic components as a result of lowering the percentage of these macromolecules, countering the optimal perception of the sweet elements. Viognier fruit is generally fairly integration of the structural and textural components.12 This may low in acidity. Wine pH may be relatively high—particularly if be very important in Viognier produced with skin contact and, the vine was over-cropped, moisture stressed, and if skin contact therefore, with an enhanced phenolic load. Additionally, if Viognier is used that may impact mouthfeel components.13 On occasion is fined prior to aging, some macromolecules are removed. This winemakers bottle with elevated levels of carbon dioxide to both can exert a negative influence on structure and texture integration. increase the perception of acidity or freshness and to increase the aromatic intensity. Correlations with Acidity - Sugar Phenolic elements + Tannins The qualitative and quantitative nature of phenols impacts their sensory characteristics and wine balance. Winemakers frequently - Polysaccharides and mannoproteins attribute Viognier coarseness to phenolic elements. Causes of +/- Body/volume structure and texture coarseness have been reviewed by Richard + Tannin intensity Gawel14 and include: + Dry tannins • Phenols including hydroxycinnamic acids, flavonols, flavanols + Bitterness and tyrosol + Carbon dioxide • Oxidation products • Glycosides • Alcohol • Acidity. COLD AIR DRAIN® Frost Protection Viognier fruit-processing methods (whole-cluster press, destemming, crush with or without skin contact, contact time and temperature) impact phenol extraction from this relatively high-phenol grape. Modification of the phenol concentration may be achieved through oxygen management, including limiting pre-fermentation sulfur dioxide (which will enhance phenol

polymerization and precipitations) and by cold settling and/or pre-

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® not simply a change in phenol concentration. This may explain why [email protected] Toll Free 877-842-9688 SHuR FARMS different wines react differently to the same type and concentration www.shurfarms.com Frost Protection 1890 N. 8th Street, Colton, CA 92324 Celebrating 11 years of innovation and cold air drainage technology! of the same fining agent. Mouthfeel may also be impacted by

filtration, which can remove colloidal macromolecules.

68 Wines & Vines FEBRUARY 2013 WINEMAKING

small concentration of sugar, juice, etc. The A universal problem in Viognier A universal problem fact that dry tannins are not well masked production is that elevated levels (above ... is that elevated by sugar suggests this approach is not 14.5%) of alcohol can increase the always effective in Viognier if the phenol perception of bitterness. The negative levels of alcohol can elements have not been properly managed. correlation between polysaccharides and bitterness is a reason for the use of high increase the percep- Correlations with Bitterness polysaccharide-producing yeast and the use of addition agents such as gums like + Ethanol tion of bitterness. Gum Arabic and yeast fining. + Grape and tannins, including im- Viognier fruit contains terpenes, and a mature seed tannins correlation between bitterness and Correlations with Tannin Intensity + Acid, specifically malic acid glycoside concentration has been reported.17 + Acidity + Yeast in suspension The use of so-called flavor-enhancing + Volume/body/sweet - Polysaccharides enzymes, which contain glycosidic activity, + Yeast in suspension + Non-soluble solids - Polysaccharides

In Viognier, tannin intensity does not An opportunity for always strongly correlate with the total phenol concentration. For example, tyrosol Tasting Room Suppliers has been estimated to comprise 10% of the total phenolic content of white wines,15 and tannin taste has been correlated to tyrosol. It is thought to be formed from the amino acid tyrosine by yeast during fermentation.16 The concentration is believed to depend primarily on yeast strain, initial concentration of sugars and tyrosine in the must. Winemaking practices such as oxidative must handling may lower the tyrosol concentrations.

Correlations with Astringency + Grape and oak tannins + Acidity 0 Sugar A new eNewsletter - Alcohol up to about 14%, + above 14% from Wines & Vines: + Non-soluble solids Tasting Room Focus

Qualitative change in phenols due to oxidative polymerization and protein precipitation can result in softer astringency, which can lower the perception of the acidity and increase the perception of the sweet elements.

Correlations with Dry Tannins - Alcohol up to about 13%, + above 13% 0 Sugar + Grape and oak tannins, including seed tannins Sell to your target audience + Acid, mainly malic and acetic + Yeast in suspension Contact us for more details + Non soluble solids (866) 453-9701 • winesandvines.com - Polysaccharides

Some attempt to provide sweetness and/ or body or volume with the addition of a

Wines & Vines FEBRUARY 2013 69 WINEMAKING may contribute to the problem. Glycoside hydrolysis releases how to best reflect the expression of this important grape variety volatile terpenes, possibly increasing aroma intensity, but also from each vineyard site. phenols, possibly increasing coarseness or bitterness. Bruce Zoecklein, professor emeritus and former head of the Enology-Grape The kaleidoscope of viticultural and enological considerations Chemistry Group at Tech in Blacksburg, Va., also served until recent- reminds us of the complexity of our industry and how practices ly as state extension specialist. I would like to thank my colleague Dominique and philosophy can change as new information is acquired. Delteil for his knowledge and suggestions on wine component integration. Premium Viognier winecrafters continue to strive to understand This article is adapted from Enology Notes and available at vtwines.info.

References 1. M.G. McCarthy, R.M. Cirami and D.G. Furkaliev. 1987. “The effect of crop load Depend. 60: 199-206. and vegetative growth control on wine quality.” In Proceedings of the Sixth Austra- 9. S. Escot, M. Feuillat. 2001. “Release of polysaccharides by yeast and the influ- lian Wine Industry Technical Conference, Adelaide, South Australia. T.H. Lee (Ed.) ence of polysaccharides on colour stability and wine astringency.” Aust. J. Grape pp. 75-77. Australian Industrial Publishers, Adelaide, South Australia. Wine Res. 7: 153-159. 2. J. Bergqvist, N. Dokoozlian and N. Ebisuda. 2001. “Sunlight exposure and tem- 10. S. Lubbers and A. Voilley. 1994. “Influence of mannoproteins from yeast on the perature effects on berry growth and composition of and Gr- aroma intensity of a model wine.” Lebensm.-Wiss. Technol. 27: 108-114. enache in the central San Joaquin Valley of California.” Am. J. Enol. Vitic. 52:1-7. 11. M. Feuillat. 1998. Autolyse des levures. In CEnologie: Fondements scientifiques 3. B.W. Zoecklein, T.K. Wolf, S.E. Duncan, J.E. Marcy and Y. Jasinski. 1998. “Ef- et technologiques. C. Flanzy (Ed.), pp. 444-454. Lavoisier, Paris. fect of fruit zone leaf removal on total glycoconjugates and conjugate fraction concentration of and ( vinifera L.) .” Am. J. Enol. 12. M. Feuillat, D. Peyron and J.L. Berger. 1987. “Influence de la microfiltration Vitic. 49:259-265. tangentielle des vins sur leur composition physicochimique et leurs caractres sensoriels.” Bull. ON 60: 227-244. 4. W.M. Kliewer and N.K. Dokoozlian. 2005. “Leaf area/crop weight ratios of grapevines: Influence on fruit composition and wine quality.”Am. J. Enol. Vitic. 56:170-181. 13. B.W. Zoecklein, K.C. Fugelsang, B.H. Gump and F.S. Nury. 1999. “Wine Analysis and Production.” Kluwer Academic Publishers, . 5. A.G. Reynolds and D.A. Wardle. 1991. “Impact of training system, vine spacing, and basal leaf removal on the performance of Riesling wines.” Am. Soc. Enol. 14. R. Gawel, L. Francis and E.J. Waters. 2007. “Statistical correlations between the Vitic. Tech. Abstr. 42:27. in-mouth textural characteristics and the chemical composition of Shiraz wines.” 55(7): 2683-2687. 6. C. Van Leeuwen, P. Friant, X. Chone, O. Tregoat, S. Kourdouras and D. Dubourdieu. J. Agric. Food Chem. 2004. “Influence of climate, soil, and cultivar on terrior.” Am. J. Enol. Vitic. 55: 15. T.E.Myers and V.L. Singleton. 1978. “The non flavonoid phenolic fraction of wine 207-217*. and its analysis.” Am. J. Enol. Vitic. 30: 98-102. 7. B.W. Zoecklein, T.K. Wolf, L. Pélanne, M. K. Miller and S. Birkenmaier. 2011. “Ef- 16. V.L. Singleton and A.C. Noble. 1976. “Wine flavor and phenolic substances. In fect of Vertical Shoot-Positioned, Smart-Dyson, and Geneva Double-Curtain Training ‘Phenolic Sulfur and Nitrogen Compounds in Food Flavors.’” G. Charalambous, I. Systems on Viognier Grape and Wine Composition.” Am. J. Enol. Vitic. 59:11-21 Katz (eds). , D.C., Am. Chem. Soc. 8. A. Scinska, E. Koros, B. Habrat, A. Kukwa, W. Kostowski and P. Bienkowski. 17. A.C. Noble, C.R. Strauss, P.J. Williams and B. Wilson. 1988. “Contribution of ter- Mel_Knox_Feb11.qxp2000. “Bitter and sweet 12/13/10components of 12:55 erhanol PMtaste inPage humans.” 1 Drug Ale. pene glycosides to bitterness in wine.” Am. J. Enol. Vitic. 39: 129-131.

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