The Essential Book of Fermentation (23 page)

I recount this story for several reasons. One, it illustrates how a wonderful wine can be personally historic for the impassioned wine lover. Two, it introduces you to my friend the late Joe Swan, an airplane pilot before he turned grape grower, who brought Pinot Noir cuttings from Domaine de la Romanée-Conti in Burgundy to this country and established them in his Sebastopol vineyard, where they became the widely planted “swan clone” (if you’ve had Sonoma County Pinot Noir, you’ve undoubtedly drunk wine from vines propagated from the pocketful of sticks Joe brought back from France in the 1960s). And three, it illustrates how fine wine is, after all, an agricultural product, grown on wine farms. Some of these farms are huge agribusiness affairs, drenched in chemicals and producing indifferent wine. But others are artisanal wine farms—small to medium-size estates, similar to the small chateaux of France—that are often farmed organically or at least in a low-input, sustainable manner. It is the latter kind of wine farm we’re interested in here—especially in the surpassing quality of their wines and how they get that way.

The Origin of Wine Flavor

What causes the unique, delicious flavors of wine? Are they in the grape juice to begin with and then unlocked by the action of yeast? Or are they formed by yeast from precursors in the grape juice? Or are they something the yeast itself imparts to the wine? The answer is all of the above.

The grape berry has three parts—the skin, the pulp, and the seeds. In general, the fruit flavors, color, and aroma compounds are found in the skins. The tannins are found in the seeds—or rather on the seed surfaces. And the sugar and liquid juice are found in the pulp. These three parts of the grape are compartmentalized from one another—until crush, when the grape bunches are run through stemmer-crushers. As the name of the piece of equipment suggests, it takes the stems from the bunch and ejects them, then crushes the berries so that tannins mix with skins and juice in a big soup called must. Large wineries use fermenting vats, but for small batches, nothing beats tromping on the grapes with bare feet, which gently separates the berries from the stems and crushes them. The stems—which are also high in tannins and would make the wine too tannic if significant amounts of them were allowed in the fermenting vat—can then be removed from the crushed grape must with a pitchfork. I’ve done the job both with stemmer-crusher and by foot, and the very best way for the home winemaker is to open a good bottle of wine, put your spouse in the vat with the grapes, put on a recording of Sousa marches, and encourage him or her to tromp those grapes with sips of wine, shouts of joy, and lots of kisses.

The flavor-color-aroma compounds in the skins would oxidize quickly if it weren’t for the tannins that are now mixed with the crushed grape juice. Tannins are used to preserve hides, and they do just as good a job preserving the fresh fruitiness of grapes. These flavor compounds are called phenolics. Some are astringent, some bitter, some sweet, some fruity, and some—anthocyanins—are the source of color as well as flavor (and even a bit of sweetness given not by sugar but by glucose-like substances associated with them). When the anthocyanins are mixed with tannins, they are called complex anthocyanins, and you can thank them for the wonderful flavors and aromas of your wine.

Esters in the grape berries are also responsible for the aromas of good wine—the black cherry, tropical fruit, blueberry, and other smells that contribute so much to the flavor of wine. There are only five tastes—sweet, sour, salty, bitter, and umami—and all the rest of what we think of as flavor in wine comes from its aromas. Esters, too, are preserved by tannins. Young tannins in newly made wine can be aggressive: mouth-puckering, astringent, and gritty. As wines age, these tannin molecules form polymers, or longer chain molecules, and give a much softer effect in the mouth. Winemakers encourage tannins to form long-chain polymers in young wines by allowing extra time—usually twenty-eight days or more—in the fermenting vat for the skins and seeds to be in contact with the new wine. This technique is called extended maceration, and wine finishes with softer, less aggressive tannins.

The yeast adds a lot to the wine during fermentation, forming volatile fatty acids that give the wine a racy, sometimes meaty aroma and flavor. When yeast cells die, they spill their cell contents into the wine (a process called yeast autolysis), and this brings toasty brioche characteristics to the wine.

In addition, terpenes are substances that are bound to the sugar in fresh grape juice. When the yeast nabs the sugar to ferment it to alcohol, the terpenes are freed and lend spicy flavors and aromas to the wine.

The yeast also changes sugar into ethyl alcohol (or ethanol), liberating carbon dioxide as it does so. If you’ve ever seen saccharomyces going after a vat full of sugary grape juice (ripe grapes can be 25 percent sugar or more), you’ll have seen the must literally boiling with bubbles as the liberated carbon dioxide comes off. Winery workers have to be extremely careful when working around tanks of fermenting must lest they enter an area where carbon dioxide, which is heavier than air and is odorless, has pooled and driven off the air. Workers have been known to pass out from lack of oxygen and then die from asphyxiation, not because carbon dioxide is poisonous, but because it has replaced oxygen-rich air.

Other contributors to wine quality include what was formerly called
Leuconostoc oeni,
but has now had its name changed to
Oenococcus oeni.
These bacteria change malic acid—a rather harsh and bitter acid—to lactic acid, which has a softer texture and buttery flavor. This is the malolactic fermentation, and it has nothing to do with yeast; it’s strictly bacterial. Winemakers add
Oenococcus
to musts near the end of the sugar-to-alcohol fermentation so the malolactic fermentation will be completed at about the same time. Otherwise the wine may decide to wait until springtime, when the weather warms up, to go through a spontaneous malolactic fermentation and push the bungs out of the barrels. Here’s another area where genetic engineering is being pursued. Scientists have inserted the gene from
Oenococcus
that changes malic acid to lactic acid into
Saccharomyces cerevisiae
so that the yeast might do it all—convert sugar to alcohol and malic to lactic acid. So far, the modified yeast hasn’t been able to convert enough of the malic to lactic to make the strain worth using. But that may change with time.

Alcohol itself is a good solvent and lifts the flavors and aromas to our palates and spreads them around inside our mouths. Think of a good perfume—the scent is in an alcohol base for the same reason. When wine tasters want to really get a good impression of a wine, they chew, slosh, and bubble air through the wine in their mouths so that the aromas go up the back of their noses. This is called the retronasal, and it allows for the fullest appreciation of a wine’s “stuffing,” as the pros call the flavors, aromas, and nuances of a fine wine.

What Vines Prefer

Now let’s talk about viticulture—the farming of grapevines that give us that marvelous fruit. Most agricultural crops prefer deep, dark, crumbly rich soil churned by earthworms, plenty of water, tons of sunshine, and warm nights. But not wine grapes. The best wines are made from vines that have to struggle. Do you have poor, shallow, rocky soil that doesn’t appear to be good for weeds, let alone grapes? Good. Lack of water just when the summer is at its hottest? Great. Cool, even cold, nights? Perfect! The gnarly old vines just a couple of feet tall that claw to stay alive in the dry soil on the rim of an extinct volcano on the island of Santorini in the Aegean Sea produce some of the best wines of Greece.

In Spain, Italy, and in California’s wine country, it usually doesn’t rain from May to October—pretty much the entire growing season, bud break to harvest. Where the climate is more forgiving, such as France, growers stress their vines by forcing them to compete intensely for whatever sustenance is available, cramming them together in tight rows—up to 11,000 vines per acre compared to about 680 in a typical old-fashioned California planting—and by planting them on the stoniest, chalkiest, driest soils they can find. In Bordeaux, the finest red wine grapes are grown on the gravelly slopes of the gently rolling hills, the lesser white wines planted in the more fertile valleys.

But why would harsh conditions favor fine wine?

The answer lies in the way vines respond to environmental stress. Grapes are tenacious, able to withstand the annual summer droughts of the Mediterranean climate and still ripen into a generous crop of fruit. They do this by plunging their roots deep into the earth, six feet or more straight down, where enough residual soil moisture from winter rains exists to keep them functioning. Such deep roots allow them to absorb minerals from rocky subsoils that strengthen them and lend nuances of flavor to their fruit. Even more important, vines respond to lean soil and lack of water by keeping their grape berries small. Herein lies one of the main keys to wine quality.

Most of the color, aroma, and flavor compounds in grapes are found in the skins. The center, fleshy part of the ripe berry is mostly water and sugar and tannins that coat the seeds. With lush conditions, grape berries grow large and watery. Small berries have a greater ratio of skin to juice than large berries, and therefore concentrate their flavor and aroma characteristics in much smaller amounts of juice, which translates into powerful, rich, luscious wines. So it behooves fine wine growers to plant their vines in places where few other commercial crops will grow.

Fine wine grapes are tough plants—as long as the temperature in the winter is mild. Severe frost—anything much below 0ºF—kills the canes and buds. If the frost penetrates into the ground deeply enough, it can kill the roots.

And so fine wine culture has developed in those parts of the world where hot, dry summers and mild winters are the norm. Because grapevines are dormant in the winter, they are only in leaf and fruit during those hot, dry months. As anyone who has lived on the East and West Coasts of North America can attest, the insect populations and densities in the two places are as different as night and day. Summer in the wet, humid East means insects and lots of them, rots, molds, mildews, and more. On the West Coast, people often don’t need screens on their windows and deck living is the norm owing to the lack of insects. Which means that small artisanal wine grape growers in California, at least, have traditionally gone easy on the chemicals, even if the big wine producers have in the past made grapes one of the most heavily sprayed crops.

A decade and more ago, most vineyardists used chemical fertilizers and nasty chemical fungicides like captan, ferbam, and methyl bromide, applied either to the leaves of the vines to thwart mildew, anthracnose, and botrytis rot, or to the soil to conquer root rots. Many growers routinely used chemical pesticides as a preventive against insect pests, whether the pests were in the vineyards or not. Many used herbicides in the rows to suppress grasses or broad-leaved weeds. The idea was that only the vines were allowed to grow in the vineyard—everything else had to die. But sterilizing the environment caused more problems than it solved. The chemicals were environmentally expensive to make, taking great quantities of energy in their manufacture. And they were expensive for the growers to buy, raising costs. They persisted in the soil, creating lifeless dirt that, exposed to heavy winter rains, eroded at ever more rapid rates, clogging streams with silt and hastening the eutrophication of ponds and lakes. These chemicals entered local ecosystems, damaging the health of the flora and fauna exposed to them—including farmworkers, neighbors, and customers. The chemicals killed almost all the insects—especially beneficials, which as a class are most susceptible to pesticides. The ones they didn’t kill were those few pests that mutated to withstand the chemical assaults. These insects bred new generations of resistant pests, and the growers had to resort to new, and usually more toxic, chemicals to kill them. Which led to more insect mutations and resistance in an ever-intensifying spiral of poison, death, and ecological havoc.

But some growers, the organically minded ones, didn’t use chemicals in their vineyards at all, and they did just fine. And for the past fifteen years or so, fine wine grape farming in California has been turning organic at an ever-increasing pace. Most of the wineries in Napa, Sonoma, and Mendocino counties have instituted some organic techniques, even if they reserve the right to use a chemical to bail themselves out of a crisis and therefore don’t qualify for organic certification.

A Strong Environmental Consciousness

I recently polled winemakers and vineyardists in these three counties, and every single one said they believed in a natural, sustainable way of farming that protects the environment. Robert Mondavi Winery’s line of wines “are blended from naturally farmed grapes,” according to a Mondavi spokesperson. The winery joined Earthbound Farm, a large grower of organic produce in Carmel Valley, California, in an event celebrating “two of life’s greatest pleasures—naturally farmed fine food and wine.” However, “natural” and “sustainable” farming have no meaning defined by law, and are certainly not synonymous with organic farming. Lately the public has been clamoring for anything organic. Organic products have enjoyed a 20 to 25 percent annual growth over the past decade, while traditional grocery sales are growing at only 2 to 3 percent, according to the Hartman Group, a research company based in the state of Washington. Some of this demand is driven by a sophisticated understanding of and belief in organic methods, but most is likely the result of the public’s leeriness of genetically altered crops and pesticide-laden foods, and its genuine desire for a safe, wholesome food supply produced in a safe, wholesome environment.