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Creating the Conditions for Graceful Aging

Every wine has one of three purposes: to delight, to impress, or to intrigue. Generous, pleasant wines make us smile (the “yummy” style). Big, impactful wines with aggressive tannins and high alcohol are designed to blow us away (the “wow!” style). These styles have grown in popularity in recent years, paralleling the trend in cinema, with comedy and action/adventure films now surpassing dramas in popularity.

Box office receipts have waned for the third style: wines that make us think. Distinctive wines-of-place that call on us to ponder new experiences are not the rage. Yet these wines represent the core aesthetic that makes wine special. Distinctive wines of place carry the torch (we might call these the “hmmmm . . .” style or perhaps the “Aha!” style) for the entire wine industry, and without them, we might just as well drink vodka. They don’t run with the traffic, and that is their appeal. When you serve them, expect way more head scratching than giggling.

While Internet chatter about the importance of this type of wine far exceeds the public’s interest as expressed in dollars spent, it’s the genre most winemakers get in the game to make, and also their path to being taken seriously by sommeliers and critics. And although these are not the grocery store commodity wines that move all those boxes, distinctive wines-of-place produced in tiny quantities in every corner of North America today make up the overwhelming majority of wine labels.

I like the term wines of discovery for these wines, whose purpose is not to shoot your basket but rather to make you dribble down to their end of the court. Here you are in the age of convenience, encountering wines that need age. Balls. Now you have to go out and rent cellar space.

The test of time is an important dimension of these wines of discovery. The pursuit of enhanced maturity allows us to choose between making vins de garde, which achieve greatness after extensive aging but are troublesome in the cellar, and vins d’impact, well-behaved young musts that require little attention and are easily bottled in youth but lack longevity and distinctiveness.

Every wine has a trajectory in time. If wine were baseball, a fruit-forward vin d’impact would be a pop fly, compared to a line drive reserve-style vin de garde. Generally, the better a wine tastes in youth, the shorter its life expectancy. Every winemaker would love to produce wines that drink well both in youth and with age, and widening the arc of a wine’s trajectory is certainly the winemaker’s Holy Grail. It is also an attempt to defy gravity.

The wise winemaker chooses the wine’s purpose early on. Choices favoring one or another style begin in the vineyard years before harvest, starting with its location and varietal selection and culminating in harvest maturity decisions. In recent years, many techniques have been developed in both the vineyard and the cellar that can push wines into early affability or instead increase longevity and profundity. With skill, and to a limited extent, it is possible to do both.

The aim of postmodern winemaking is to capture what Nature has put in a vineyard’s grapes and present it with grace and balance. As a branch of cuisine, winemaking, the ultimate slow food, has much in common with the making of sauces, because the soulfulness of flavor integration is a result of refining its structure. Granted, wine is not an emulsion like mayonnaise: the particles that make up the structure of a wine are not tiny beads of oil but instead are made up of phenolic chains that aggregate into tiny globs called colloids. But in both cases, the particles’ shape and size affects their power to integrate flavors. For this reason, wine’s texture is strongly related to its aroma.

Control of tannin polymerization is a central postmodern skill. Small, stable colloids not only impart finesse and soulfulness in youth, but they also prolong wine’s longevity. Poorly formed tannins precipitate readily over time. When this happens, just as in the curdling of a sauce, aromatic integration is lost. Elements previously married become individually apparent, resulting in wine that seems over-oaked, vegetal, or Bretty. Wines with well-formed structure can carry much higher concentrations of these aromatic elements without offending the nose.

The willful formation of structural integrity by the winemaker is termed by the French élevage, and successful wines are said to have race, or good breeding. Like all good cooking, élevage methods require training and attention to detail. Good structure begins in the vineyard with vine balance.

Winemakers will always say they do the minimum. Try that on your three-year-old. Still, a good winemaker, like a good parent, strives to become invisible. The final product must sing its song of place, and the skill of the winemaker, like that of a good piano tuner, should go unnoticed.

CONNECTING THE DOTS

Over the past two decades, a picture of the nature of wine structure has slowly emerged that we will explore throughout this book. While much of this mental construct lacks direct confirmation, the same could be said for many embodiments of modern science such as the Periodic Table of Elements, which lacked direct evidence in its first hundred years. It has been my privilege since 1997 to work closely with Patrick Ducournau’s OenoDev group, based in Madiran (Hautes-Pyrénées), who painstakingly knit together a working hypothesis that guides postmodern practice by combining empirical observations of many thousands of wines with recent advances in phenolic chemistry, largely centered at Montpellier under Michel Moutounet and Véronique Cheynier but also involving the Australian Wine Research Institute’s Tannin Project and work at UC Davis by Roger Boulton on copigmentation and polymerization studies by his colleague Doug Adams, all founded on Vernon Singleton’s life’s work on phenolic oxidation, the focus of chapter 6.

I was able to contribute to this brain trust Vinovation’s trials with ultrafiltration, through which we obtained direct evidence of noncovalent bonding that empowered investigations of colloidal behavior in red wine. Through my consulting work, I have also had the opportunity to road test the emerging theory by working with hundreds of winemakers and thousands of wines over the past decade and a half.

I am the first to concede that this view of wine structure is little more than a useful working construct, but I have found in it substantial utility for guiding winemaking decisions. Scientific verification is not the engine of progress in winemaking today; it is the caboose. As in any cooking technique, empirical successes initially drive theory. What follows, therefore, is probably not true in all its elements. But there is no doubt of its usefulness as a guiding schema.

BUILDING BETTER WINE

Tannins already exist in the ripe berry skins and seeds as polymers. Much attention has been focused on the ingenious and laborious work done at Montpellier on the degree of polymerization (DP) that exists in grape skins and seeds. But these polymers are unlike those we are trying to build in finished wine. As soon as they hit the highly acidic grape juice, they break down into monomers, which collect into colloids, later reassembling into wine polymers through a variety of pathways. Anything we might learn about grape tannin polymerization is lost in the chaos of fermentation. Over months and years, these monomers reassemble like Lego blocks, forming two kinds of permanent chains (nonoxidative and oxidative) with very different sensory properties.

Nonoxidative polymers have a soft, nonintrusive mouthfeel in young wine but tend to continue growing until they become harsh and eventually insoluble, falling out of the wine. We don’t like these polymers.

Fine colloidal structure depends on the promotion of early polymerization while at the same time preventing it from getting out of hand. It turns out that the key to good structure is a good concentration of red anthocyanin pigment. Color caps off tannins, leading to wines with more finesse. In effect, the more color that is present, the shorter the resulting polymers and the finer the colloids (figs. 2 and 3). Driven together by the polarity of water, these chains aggregate into colloids whose size is related to the chain length of its constituents.

If oxygen is delivered to a young red wine, a different kind of polymer results that is more expanded. In much the same way a wire whisk creates meringue from egg whites, skillful introduction of oxygen to young red wine creates a mouth-filling, light structure that is stable and can form a foundation for soulfulness and graceful longevity. That’s why the Aztecs taught the the Spanish explorer Cortés the use of oxygen (“conching”) to convert cocoa powder into chocolate, still a standard practice in the finest Belgian shops (yes, that chocolate waterfall in Willy Wonka’s Chocolate Factory really exists!).

In red wines, prompt action is critical, because color molecules (anthocyanins) are easily lost to precipitation, yeast adsorption, and enzymatic attack. Successful oxidative structuring is best begun within days of the completion of alcoholic fermentation, sometimes even under the cap.

FIGURE 2. Polymerization with poor color.

FIGURE 3. Polymerization with good color. High anthocyanin ratios result inshort, soft, stable oligomers.

The mechanism of oxidative polymerization was elucidated in 1987 by Vern Singleton, who found that certain phenols found in grape skins could take up an O₂ molecule and become highly reactive, linking up to other phenols.¹ Singleton discovered, bizarrely, that the starting structure gets re-created at the end of the reaction in an increasingly reactive form, available to react over and over, resulting in a cascading polymerization effect. The reaction is homeopathic: early introduction of oxygen actually increases the wine’s antioxidative power.

Understanding the ins and outs of the vicinal diphenol cascade is essential to a grasp of red wine’s fundamental chemistry, and I have dedicated chapter 6 to exploring its mechanism and implications. Here I’ll just touch on the high points.

The Golden Ratio

It has been empirically determined that a molar ratio of 4:1 total phenols to anthocyanins is ideal for good structure. Since anthocyanins are phenols too, this means the ideal polymer has about six units, with anthocyanins on each end, with a total molecular weight (MW) around 2,000. Yet these covalently bonded polymers aggregate into colloids that pass only with difficulty through a 100,000 MW ultrafilter, demonstrating that several dozen such oligomers (short polymers) are contained in a single colloid and hinting at the destructive potential for sterile filtration, which typically operates near this size range.²

Intentional encouragement of oxidative polymerization in nascent red wine is referred to as Phase 1 micro-oxygenation, which requires high-performance diffusion equipment that produces extremely small bubbles of pure oxygen that readily dissolve before reaching the wine’s surface. Splashing will not suffice. Since tannin polymerization is energetically favored over oxidative ring cleavage, it is critical to introduce oxygen at a rate slow enough to be entirely taken up by this reaction, thus preventing oxidation. Patrick Ducournau was the first to develop an oxygen diffuser that could regulate the extremely low flow rates necessary.

Oxygenation at this early stage does not shorten the wine’s life; paradoxically, it increases antioxidative power by stimulating latent phenolic reactivity. In fact, stopping abruptly will stimulate reductive behavior, causing the wine to close up aromatically and produce stinky sulfides. This is not a bad thing but rather a sign of longevity potential. Oxygen treatment may be extended to balance reductive strength as desired, depending on the intended aging trajectory. Tannins move from green to hard, lose their graininess, and gain volume in the mouth due to an expanded structure, eventually softening into a plush, stable mouthfeel.

While color is critical to creating refined texture, the winemaker should not be fooled by highly colored musts that have experienced field oxidation due to extensive hang time. These do not form stable structures. Only monomeric (unpolymerized) color is useful in refining structure.

When conducted prior to the addition of sulfur dioxide (SO₂), Singleton’s cascade includes a second reaction, one that also stabilizes color. Hydrogen peroxide is a side product of the reaction, which, in the absence of sulfites, will oxidize a molecule of ethanol to acetaldehyde. This compound, responsible for the stale apple aroma in fino sherries, is problematic in mature wines but a godsend in young red wine. It bridges pigments to tannins, doubling the rate at which oxygen stabilizes color. Once incorporated into polymers, the anthocyanins become protected, also shedding their susceptibility to sulfite bleaching.

Even if oxygen is not employed, color will still improve structural finesse. Despite its high tannin levels, Syrah texture is dependably soft, while Pinot Noir, though much lighter, is notoriously susceptible to the coarse, dry mouthfeel associated with overpolymerized tannins.

Pinot is a tough town. Anthocyanins contain a glucose molecule that stabilizes their structure, and in most grape cultivars this is protected by an attached two-carbon acyl group that blocks attack by most glucose-loving enzymes. But Pinot Noir pigments lack acylation. Moreover, the grape’s weak tannins are insufficient to promote good yeast settling. Yeast and suspended grape solids not only adsorb pigment but also have a voracious appetite for oxygen, much greater than diphenols, thus thwarting polymerization and color stability.

A Season in Heaven or Hell

Although each vineyard has its own charms and virtues, it is a universal concern that red wines with low color/tannin ratios form coarse, grainy structures that lack integrative properties and shelf life. The path to sound, integrative structure and graceful longevity involves

1 balancing the vine;

2 picking at the proper moment;

3 facilitating effective coextraction; and

4 stabilizing structure.

Any misstep in this chain of events means that little can be done to enhance structure without remedial interventions in the winery such as component blending, lees incorporation, or even sugar addition.

Vineyard Enology

Within a growing season, efforts are generally focused on vine balance, a topic of great complexity that merits its own discussion (see chapter 5). For now, let’s focus on optimizing the development of flavor, tannin, and color.

Pigment and flavor elements are formed in grapes beginning at véraison (the onset of coloration) in order to attract birds to ingest mature seeds. This shift in the vine’s attention from green growth to reproduction is known as Cycle Two. The vineyard enologist strives to encourage a marked shift into Cycle Two by balancing crop load, judicious nutrient availability, and moderate water stress, thereby promoting light exposure, air movement, and moderate temperature in the fruit zone. If Cycle Two does not proceed enthusiastically, it is well to have highly colored components available for blending. If all goes well with Cycle Two, then choosing an optimum moment for picking is the next critical step.

Ripeness, Style, Nature, and History

There is no single definition for the right degree of ripeness. Ripeness per se does not exist outside of the winemaker’s intentions about food functionality, fruit-forwardness, flavor density, structural integrity, and longevity.

The Loire appellations have become known for chenin blanc picked in three styles (remember, my convention is to capitalize the names of varietal wines and lowercase the names of grapes). The crisp, fresh, floral wines of Vouvray are gathered in early maturity before the mown hay/summer meadow notes of Savennières develop. Coteaux du Layon requires extensive hang time and botrytis to produce its honeyed vins liquoreux. Heat summation and season length to some extent dictate what can be done, but doubtless Vouvray-style wines could also be made in warmer upstream areas. In California, where no regional régisseur is looking over one’s shoulder and there is no fear of rain, we can do as we choose, targeting an off-dry, stainless steel–fermented quaffable wine for mass appeal or a complex sur lie, barrel-fermented, age-worthy Chenin Blanc aimed at the connoisseur.

In reds, control of tannin polymerization is a core postmodern skill. In determining ripeness, attention is centered on creating a good concentration of unpolymerized anthocyanins in the finished wine that will restrict tannin polymerization, leading to wines with finesse.

Optimum ripeness is a complex determination. Underripe grapes may not contain the optimum concentration of anthocyanins, may be difficult to extract, and also may lack desired fruit flavor density. Cellular breakdown in the skin, which releases pectinases that greatly aid extraction by reducing pulpiness and releasing pigment, may not have occurred. Malic acid reduction occurs throughout ripening and is advantageous to mouthfeel because excessive acidity overstimulates salivary response and brings excessive protein into the mouth, leading to coarse mouthfeel.

These difficulties pale in comparison to the perils of overripeness. To work well in the cellar, the reactive potential of tannins and anthocyanins must be protected from field oxidation. We are trying to make a tannin soufflé, and if the eggs are already scrambled, there is nothing that can be done in the kitchen. The tannins that result from excessive hang time are not stable and will become grainy and dirty in short order, imparting neither antioxidative strength nor aromatic integration to the wine.

Field oxidation also robs musts of monomeric anthocyanins. It is not enough to have good color; the color must be unpolymerized so it is still reactive and able to fulfill its role as a cap on tannin chains. High pH associated with extended hang time will also suppress the rate of pigment stabilization through aldehyde bridging (which is mediated by its low-pH carbo-cation form), instead promoting browning.

Sugar metabolism and the vagaries of raisining and dilution from dew and rain have little to do with maturity, and brix is an unreliable maturity index. It is a reliable guide to eventual alcohol content, but as we shall see, elevated alcohol is an enemy of color extraction.

Coextraction

In 1974, Pascal Ribéreau-Gayon published a color plate that revealed a mysterious reality: by themselves, anthocyanins are not very soluble in 12% alcohol and confer only a light pink color.³ If wine is a solution, red wine is not possible. He then showed how, in combination with tannins, the anthocyanins become deep red. Although no one knew what to make of this at the time, he was really demonstrating that color and tannin together form colloidal structures.

Recent enlightenments on the nature of extraction invite us to forget everything we thought we knew on the subject. Most winemakers concentrate on the methods of extraction: pumpover vs. punchdown vs. délestage; vigor and frequency of mixing; temperature; use of pectinolytic enzymes; and so forth.

In 2001, Roger Boulton published a review of a decade of research on copigmentation that revealed winemakers were barking up the wrong tree.⁴ Unless a home is provided for anthocyanins to extract into, no amount of punching down, pumping over, enzyme treatment, or temperature adjustment will result in stable color extraction. Boulton’s revelations concerning the makeup of copigmentation colloids showed that a color molecule was not going anywhere unless it could pair with another similarly shaped but uncharged monomeric tannin molecule, a “cofactor.” Anthocyanins can’t form into colloids by themselves because they have a positive charge and repel one another (fig. 4).

FIGURE 4. Configuration of anthocyanin vs. catechin vs. quercetin. The four bonds of carbon atoms assume a tetrahedral arrangement in 3D space. If, however, one of the bonds for every carbon in the molecule is a double bond, molecular configurations such as anthocyanins can lie entirely in a plane, stacking tightly with other planar flavonoids. The common skin and seed flavonoids are not planar and make so-so cofactors. But the UV protectant quercetin is planar, thus empowering it as a “super-cofactor” for extracting color into copigmentation colloids.

Anthocyanins belong to a class of phenolics called flavonoids, which are composed of three six-member rings hooked together. The most abundant flavonoids in skins are called catechin and its isomer, epicatechin. Unlike anthocyanins, however, these flavonoids aren’t ideal cofactors because they don’t lie flat. They’re lumpy. When exposed to moderate sunlight early in the season, grapes produce a UV protectant called quercetin, which is a more planar “super cofactor.” Boulton showed that these extractive “copigmentation colloid” intermediates are entirely composed of monomers. Oxidatively polymerized tannins resulting from extended hang time do not assist extraction, nor do most oak tannin products.

Boulton’s findings elucidated the wisdom of the practice of field blending and cofermentation of varieties practiced in many European appellations, where tannic whites are included with well-colored, tannin-deficient reds: palomino with garnacha in the Rioja, viognier with syrah in the Rhone, trebbiano with sangiovese in Chianti, as well as the interplanting in old California vineyards of small amounts of petite sirah, carignane, or alicante bouschet with zinfandel, barbera, or mataro (known now as the uptown “mourvèdre”).

In optimizing coextraction from other sources, gallic acid, a breakdown product of ellagitannins from oak, is an excellent cofactor. It is not available from the surface of toasted oak barrels, staves, chips, or dust but only from untoasted oak that has not been heated or sawn. But beware: untoasted oak typically contains the planky aromatic defect trans-2-nonenol. Unless carefully air cured in a manner that does not build up TCA (2,4,6-trichloroanisole, the moldy aroma also associated with corkiness), untoasted oak can ruin a fermentation. Thus it should only be purchased from a reputable supplier and used immediately.

Copigmentation colloids are not stable. If young reds are deprived of oxygen, they can lose their color almost overnight, and dry, grainy tannins will result. Since water polarity is the driving force holding the colloids together, copigmentation does not occur at all at 20% alcohol, and thus precipitation may even take place near the end of high-brix fermentations—another peril of extended maturity. Bitartrate crystals may also take up pigment and carry it into sediment.

If one follows a methodology to encourage vine balance, to harvest ripe but not overripe, and to provide material in the must for coextraction, the elements for graceful aging will be present in the young wine. We have bought ourselves a ticket, but we have not arrived. In fact, if the fruit is exceptional, we have now created a monster: aggressive, reductive, and quite unpleasant. Taming this beast, feeding its appetite for oxygen, will provide the driving force for our tannin soufflé. Judicious blending and proper oak choices are best made immediately. The ins and outs of élevage technique are the subject of the next chapter.

TAKE-HOME MESSAGES

 A fruit-forward impact wine compares to a reserve-style vin de garde as a pop fly compares to a line drive.

 Winemaking is a branch of cuisine—the ultimate slow food—and has much in common with the making of sauces, because the soulfulness of flavor integration is a result of refining its structure.

 Oxygenation at this early stage does not shorten the wine’s life; paradoxically, it increases antioxidative power by stimulating latent phenolic reactivity.

 If one follows a methodology to encourage balance in the vine, harvests ripe but not overripe, and balances the must for coextraction, the elements for graceful aging will result.