Kindle Notes & Highlights
by
Clark Smith
Read between
February 18 - March 12, 2020
Yes, Virginia, wine gobbles up oxygen. Poof—gone! And in doing so, it can convert its vitality into structure the same way a wire whisk whips egg whites up into a meringue.
It’s not unusual for a new tannat to consume oxygen at one hundred times the rate a barrel supplies. The main purpose in bringing oxygen to a new red wine is to stabilize color. The red anthocyanin pigments that give wine its hue also have the property of capping tannins, restricting their length by terminating their polymerization.
Oxidative polymers possess freely rotating linkages and are less compact than are nonoxidative ones, resulting in a larger perceived volume in the mouth and an aggressive hardness, a sheetlike grippiness, entirely on the top of the tongue, that causes it to stick to the roof of the palate (tanin dur, or hard tannin). Over time, as lees proteins and other side reactions coat the tannins, blocking salivary protein interactions, these hard, grippy tannins begin to melt at the back of the tongue, eventually softening completely, producing a velvety impression and a great deal of aromatic
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Oxygenated wines are aggressively tannic in youth compared to their untreated counterparts, often coming to resemble them after about two years, after which the MOx wines steadily improve while untreated wines begin to dry out.
Blasting in oxygen in short bursts is not MOx, and actually has reverse effects, breaking down structure rather than building it, in the same way that blackening a steak is diffe...
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Winemakers increasingly view oxygen the way a carpenter treats a power saw—as a dangerous but essential
Phase 3 is also employed to knock down reductive strength prior to bottling, particularly in preparation for bottling under screw caps, which do not supply a burst of oxygen as corks do by virtue of their compression when inserted.
Thinking of MOx as a way to rush wines cheaply to market is like thinking of your Lamborghini as a really good flashlight. Which it is.
I think of lees as being like egg yolks and tannins the egg whites from which we will make a soufflé. To begin with, the yolks must be separated out and set aside while we turn our attention to the whites, whisking them into a rich, light meringue. Once we have the structure built, we fold the yolks back in for a rich fatness. In the same way, we first oxygenate tannins into a mouth-filling, refined structure. Just as the presence of yolk prevents the formation of meringue, early lees stirring prevents oxidative tannin structuring and destroys color. Only after the structure is complete and
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My favorite corollary of Murphy’s law states that nothing is impossible for the man who doesn’t have to do it himself.
Over-oaked wine is just bad cooking.
Oak’s proper use is to correct imperfections so the real wine can emerge. Any defense attorney makes sure the defendant is neatly groomed and attired before appearing before a jury. This isn’t a charade; it’s a convention that allows judgment of the real person rather than the unkempt trappings.
Untoasted oak is a rich source of hydrolyzable tannins called ellagitannins, which break down in must to yield prodigious quantities of gallic acid, a powerful cofactor.
Green untoasted wood contains trans-2-nonenol, a nasty, planky sawdust aroma that persists in wine for years. To prevent this, oak needs curing outside in weather that will leach tannins and foster subtle microbial transformations. Curing wood is an art, and skill is required to avoid the formation of TCA, the corky aroma. Thus only highly reputable coopers should be entrusted with the production of untoasted chips or barrel heads.
Some wines start off with excellent fruit core but lack definition—this is typically true of Barbera, Grenache, and some Merlots. Others have the frame but not the fruit, a common problem in Mourvèdre, Carignane, and Cabernet Franc.
Oak can be a source of a wide variety of sweet elements. Untoasted wood supplies a coconut influence (whiskey lactone), usually subliminal, which lifts out varietal fruit aromas. This compound is rich in French forests where sessile oak species (Quercus petraea or Q. sessiliflora) predominate, such as those of Alliers, Vosges, and Argonne. Alternatively, toasting can enrich vanilla, toffee, and sometimes sweet coffee elements. The flame converts cellulose to cellobiose, an exotic sugar that can feed Brettanomyces.
The very practices that increase color also serve to decrease veggie aromas. Pyrazines exist to repel birds, while color develops to attract them. Once the vine switches into seed-maturation mode, the flavors come into balance naturally.
principal tenets of Vineyard Enology: Promote living soil. Achieve vine balance. Harvest at proper maturity.
too little sunlight shuts down color and flavor development, but too much causes sunburn. Too little air movement leads to rot, but excessive wind results in stomatal closure and shutdown of sugar transport.
A shot of fertilizer results in more canopy, less light, higher temperatures, less air movement, and increased soil water depletion.
Grapevine life cycle in the wild. A viable grape seed exits the digestive system of a roving avian vector and is deposited in a nutritious plop of, well, bird shit. The resulting seedling finds no direct sun on the forest floor and thus produces no fruit but instead uses its tendrils to begin climbing the nearest tree. Years later, shoots emerge into the sun atop the forest canopy, and light cues stimulate the differentiation of grape clusters. A grape approaching véraison has considerable sugar, but until the seed is viable the vine must use a variety of tricks to repel birds and camouflage
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A 1996 Australian Wine Industry Technical Conference about the reproductive biology of grapes determined that the primary metabolic changes occurring in berries (sugar and acid content) were unrelated to the evolution of secondary metabolites (color, flavor, tannin).
Achieving flavor ripeness, by contrast, is simply a question of time. Riesling from Geisenheim on the 50th parallel is picked in the second week of October, when it is hoped to reach as much as 17° brix (10.2% alcohol), the legal minimum for spätlese (literally, “late picked”). Riesling in Sonoma’s Alexander Valley (38th parallel) is also picked in mid-October, but there we hope for less than 25° brix (15% alcohol). Even on a single site, the cold vintages of 2010 and 2011 taught us that California vineyards that would not achieve flavor maturity until over 25° brix in warmer years were
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After tasting a wide variety of our wines on a visit to California, he expressed the (to me) shocking opinion that, despite their high sugars, our California grapes were more often than not simply unripe. “If it were left up to me,” he said, “I would ripen to higher brix, looking for truly ripe flavor, color and tannin, and dilute the must back to normal alcohol potential.” This was before alcohol reduction technology appeared on the scene.
The Old World has long applied corrective methods. Inventive styles like Champagne and Port easily achieve an artificial balance thanks to the strategically timed addition of alcohol and sugar.
While we still don’t have a means for removing sugar per se, these methods are employed after the sugar is converted to alcohol by yeast fermentation, and the net effect is the same: “reverse chaptalization.”
postmodern principles point to some very specific desired characteristics in red musts that are our goals. Flavor finesse is achieved through fineness of texture. The smaller the grain size of the colloids that make up the tannin structure, the greater their combined surface area and thus the greater their power to integrate aromas and their stability over time. These colloidal structures are aggregates of dozens of polymerized tannins that form through the oxidative linking of a large variety of flavonoids, three-ringed compounds that are synthesized in skins and seeds during the season. The
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Color molecules are the bookends on the polymer; the more color, the shorter the polymer, and the softer and more refined the texture. But this only works if the anthocyanin is a free monomer, not already fallen victim to polymerization through field oxidation. Our goal is to time harvest in order to catch color development when the reactive monomer has hit maximum and before it is lost to polymerization—ripe but not overripe.
Winemaking is empirical, succeeding through a long succession of failures. I am sorry to confess that having opened the door to the world above 23.5° brix, I have been personally responsible for an awful lot of terrible wine being made.
“Life can only be understood backwards; but it must be lived forwards.”
Einstein said, “It is impossible simultaneously to prevent and prepare for war.”
Living soils supply plentiful and complete nutrition. Cover crops fix nitrogen, earthworms aerate soil and digest organics, and mycorrhizal fungi intercalate into grapevine root hair tissue, symbiotically trading for sugar rare trace minerals that grapes by themselves are incapable of taking up.
there are no atheists in vineyards.
All phenolics are simply derivatives of phenol itself, which is composed of a ring of six carbons with alternating double bonds (called a benzene ring) attached to an oxygen and hydrogen (-OH) (see fig.
Aromatic integration works better when the beads are very fine. This also gives a silky, refined texture to the palate. Smaller colloids mean more surface area of interface between the aqueous liquid surrounding the beads and the fatty or hydrophobic (water-hating) interior, be it a butter bead or a phenolic ring-stack. This is why textural fineness is related to aromatic finesse. The French use the same word for both.
One type of phenolic that plants find very useful in fruit is the vicinal (or ortho-) diphenol. This is simply a phenol with two -OH groups in adjacent positions on the ring. This molecule has the magical ability, in reaction with oxygen, to attach itself to another phenol and then to re-create its original reactive diphenol structure. This odd trait allows it to react over and over, daisy-chaining to create long polymers. The browning we see in freshly cut apples and bananas is polymerized diphenols, sealing the fruit in case of injury.
In effect, oxygen acts like a wire whisk, and the tannins, like egg whites, firm up into a rich, light structure similar to a meringue. In this way, the reductive strength of the wine is harnessed as an engine of finesse and soulfulness, like a churlish teenager who takes up the cello. Bottled poetry, indeed.
As I said, the more anthocyanins we start with, the shorter the polymers we end up with. Smaller polymers aggregate into smaller colloids. Not only do these feel softer and finer, but they have a greater combined surface area as well and impart greater aromatic integration. That’s why the finer the texture of a sauce or a wine, the dreamier it tastes. In general, darker-colored wines have a quality edge (Pinot Noir being the exception, as always).
Measuring the monomeric anthocyanin concentration of a young red wine to gauge softness potential is quite useful but slightly tricky. Unfortunately for the amateur wine enthusiast with a cellar, red wine’s darkness itself is not sufficient for determining monomeric anthocyanin concentration. Color density doesn’t account for the degree to which field oxidation may have polymerized pigment, particularly in cases of long hang time. Wines that look very dark may actually be quite fragile. It helps to look for an overly amber edge—a bad sign.
The best available molar estimator for anthocyanins is an offshoot of the Adams astringency assay called BP (bleachable pigment).3 It is easy to run (if you have the right centrifuge), and its LPP (long-chain polymeric pigment) is also a good analytical index of dryness. Problem solved.
The early presence of lees in young reds is deleterious for two reasons. Lees react readily with oxygen, dampening phenolic activity and suppressing the cascade. Lees also adsorb anthocyanins and contain glycosidase enzymes which attack them. Just as egg yolks prevent the formation of a meringue structure, lees must be separated through clarification in young red wine. As with a soufflé, their later incorporation after the structure is formed can be beneficial for adding fatness and richness.
The vicinal diphenol cascade reaction is extremely temperature-dependent. Because it involves two reactions (one with each of the -OH groups), we label its kinetics of the second order, a fancy way of saying that its temperature dependence is squared.
Any observant winemaker or attentive wine collector knows that young wines, especially tannic ones or minerally ones, exhibit aromas that are “closed.” That is, they have less apparent fruity intensity than they develop later in their lives, and often, in youth, reveal greater flavor intensity on the palate than in the nose. They may even produce sulfides, which aging will dissipate.
When produced from grapes containing raisining, wine has been shown to exhibit fruity elements resembling hazelnut, tawny port, and bacon, products of Maillard reactions between proteins and sugars. Since these compounds contain positively charged N+ groups, they should at wine pH be ionized, and therefore nonvolatile. If the redox potential is high, however, such a compound might accept an electron (e−) and become charge-neutral, thereby released from aqueous solution into the aroma. (See the discussion in chapter 18 on acidity and aroma.) We thus have a plausible basis for the observed
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The story of the rise and fall of the Warburg apparatus as an enological tool holds deep lessons for how science functions and how it sometimes inexplicably fails to progress. It is as if our access to knowledge, apparently ever expanding, is actually limited by our historical point of view: every time we gain new insights, we simultaneously leave behind some detail we aren’t making use of, almost at random.
Tannins require oxygen for proper evolution. This is the basis of chocolate-making, where it is called “conching.” That chocolate waterfall in Willy Wonka’s Chocolate Factory really exists. Highly phenolic cocoa extract is pumped around and falls in sheets, exposing sufficient surface for continual O2 saturation, feeding the building of structural colloids through controlled, limited oxidative polymerization that absorbs tremendous quantities of oxygen. The result is dark chocolate, which is profoundly flavorful, its texture hard rather than harsh. If milk protein is then added, it
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In each case the vicinal diphenol is re-created to react again, but then the alkyl substitution of the ring lowers the pKa (the pH at which ionization is 50%) of phenolate oxidation from about 9.0 to 8.5, effectively doubling reaction speed. This explains Ducournau’s surprising early discovery that oxygenated wines at first increase in reductive strength. Feed a wine oxygen, and its appetite increases. It’s like bodybuilding—do it right, and you get stronger, not weaker. Oxygenation is not oxidation.
A second difficulty, even more slippery, is the apparent reductive properties of minerality (see chapter 8). Here is enology’s most unfortunate and yet most promising intellectual mud-wrestling arena. On the one hand, minerality is an obvious trait acknowledged by connoisseurs and the preponderance of winemakers. On the other hand, we have no idea what it is, and it retains the academic status of Bigfoot and flying saucers.
Sometimes the word minerality refers for some people to the aroma of wet stone, for which I prefer the term petrichor, the smell of new rain as it liberates natural oils from rock in the desert.
