Lisa Wong

Frozen Fruits

Lisa Wong — Fri, 02 Jan 2015 10:18:00 GMT

Canada's Icewine & Ice Cider

Between the woods and frozen lake, the darkest evening of the year.
-Robert Frost

…many people believe that none of the four seasons accurately describe the two months of darkness that all of Canada experiences in the months of July and August, so there’s now a movement to actually have a fifth season in Canada, and we have three names: the Slumber, the Equinox, or the Canadark.
-Rick Mercer

Icewine

The above quotes may seem contradictory, but as a Canadian, my feelings on ice wine, or rather “icewine” as trademarked in Canada, are just that. Akin to my feelings for winter. Frost’s description of the hushed romantic beauty of a winter wonderland embodies a sentiment inherently linked to icewine. It’s a beauty that often enchants those who don’t have to forcibly deal with winter on a regular basis.

I can’t shake the feeling that in conversations with the international wine community, icewine comes up as something to say once it’s discovered I’m Canadian. It feels like stereotyping, but not in the same way that California Cabernet or Mendoza Malbec can be stereotyped. Not based on the fact that it’s a distinctive style of wine that has consistently been produced since the 1970s and is subject to trending perspectives, but rather based on the simplistic and almost dismissive train of thought that I’m a sommelier from Canada, and Canada is cold. Hence, icewine. For some reason it reminds me of a popular 2001 feature of the Canadian news satire show, This Hour Has 22 Minutes, where comedian Rick Mercer convinced several people in the States to say earnestly on camera that they were firmly against the “Toronto Polar Bear Slaughter” and, “Congratulations Canada on preserving your national igloo.”

Of course, there’s nothing wrong with thinking of icewine when thinking of Canada. Canada is the largest icewine producer in the world, with production in around one hundred wineries countrywide. In 2012, sales surpassed 400,000 liters, valued at over $30 million. Canadian icewines have received numerous international awards: a 1989 Vidal icewine produced by Inniskillin, the estate winery started in 1975 by Dr. Karl Kaiser and Donald Ziraldo, notably won the Grand Prix d’Honneur at Bordeaux’s Vinexpo in 1991. The style of wine historically originates from Germany (eiswein), and is thought to have been accidentally discovered in 1794 when a sudden cold snap overtook the vineyards. Almost two hundred years later, the first Canadian icewine was commercially produced when Hainle Vineyards in British Columbia’s Okanagan Valley released 178 bottles in 1978. The style has grown greatly in popularity and is now more consistently produced by Canada, where winters are more reliably cold, than by Germany.

Yes, that’s because Canada is super cold. Okay, okay. The main difference between icewine and other wines is, of course, the ice part. Specifically, the timing and temperature of harvest and pressing. But the sun and warmth of spring and summer and the extension into late fall are just as integrated into the process as the cold and darkness of winter, and there are many intricacies involved in the production process. There is more to it than just water freezing.

Regions of Production
Congratulations Canada on becoming part of North America.

To be sure, much of Canada exhibits winter climes that can be described as nothing less than frigorific. This is true particularly between December and February, when vines are in dormancy. But in the Niagara viticultural region in Ontario, where over 75% of Canada’s icewine is produced, the growing season of the grape between bloom and normal harvest, between mid-June and November, is comparable to most other cool climate viticultural regions, and can be warmer than regions such as Alsace and Champagne. The region falls between 41-44° N. Annual precipitation is around 543 mm and the mean July temperature is 22.5° C (72.5° F). Ontario has an average 1400 growing degree days—which is comparable to other cool winemaking regions in the world.

Niagara’s microclimates are tempered by Lake Ontario, which borders the north of the Niagara Peninsula. Unlike the “frozen lake” in Frost’s poem, the Great Lakes do not freeze over, and a continuous process of thermal exchange moderates the regional temperature. South of Lake Ontario, the Niagara Escarpment, a cuesta 30 to 50 metres high that runs along the peninsula, creates a recirculating airflow by redirecting air currents that pass over from the lake.

The Okanagan Valley in British Columbia, the second-largest icewine producing region in Canada, lies in a rain shadow, between the Coastal and Monashee mountain ranges. It experiences hot, dry summers (average July and August temperatures are higher than in the Napa Valley) and somewhat mild winters. The valley stretches northward 130 km from Lake Osoyoos at 49° N, at the northern tip of the antelope-brush-filled Sonoran Desert. That’s right: a desert.

Varieties
Congratulations Canada on reaching a population of one million.

Uncomfortably low temperatures are necessary for icewine harvest, but cool climate growing conditions and compatible varieties are ideal as slow ripening factors affect the rate of acidic and aromatic development—two aspects which are essential in balancing the concentrated sugar content. Prolonged over-ripening may result in a net loss of some aromatic compounds, and in the extreme cold potassium tartrate crystallization will result in a loss in acidity. At the same time there is a certain amount of concentration of acids and aromatic compounds occurring alongside the concentration of sugars. For the winemaker, striking the perfect balance is complicated.

The most common grape varieties for icewine production are white varieties: Vidal, Riesling, and Chardonnay. And Cabernet Franc is becoming increasingly popular for red icewine. Other varieties include Gewürztraminer, Merlot, Pinot Gris, Muscat Ottonel, and Gamay. Most of these are common European vinifera grapes, which in the 1970s replaced most of the labrusca and other non-vinifera varieties that had been planted in Canadian wine regions as early as 1811. However, the hybrid Vidal is quite suited to icewine production and is more extensively planted in Canada than any other country. It was developed in the 1930s by Jean Louis Vidal in Charante, France by crossing Ugni Blanc and the non-vinifera Rayon d’Or (Seibel 4986). Brought to Canada in the late 1940s by the French oenologist Adhemar de Chaunac, Vidal was first commercially employed by Ontario wine producer T.G. Bright & Company (later known as Brights Wines and now part of U.S. conglomerate Constellation Brands). Its attributes include slow and steady ripening, thick skins and high aromatics.

It is also quite winter-hardy. Winter is often associated with silence and sleep—“the only other sound’s the sweep of easy wind and downy flake”—as the weather becomes too cold for even the most corpulent of critters and pestilent of pests to cause a stir. It is a quiet that can cause a permanent silence for many plants. Death. Less poetically known as death. The very water molecules of plant cells are quieted as kinetic energy lowers, vibrational forces change, molecules rearrange and the expansion of intracellular fluid as it converts to ice bursts the cells. Cold acclimation and freezing tolerance in temperate plants involves a genetically programmed, integrated process. Upon impetus, such as photoperiodic changes, shortening day length and decreases in temperature, the plant tissues undergo alteration that improves cellular freezing tolerance, which involves protective freezing of the fluid surrounding the cells. As extracellular fluid freezes, water osmotically moves to the outside of the cell, increasing the inner solutes and concentrating the intracellular fluid, which makes it more difficult to freeze (think of how we use salt to dissolve ice). The plants can stay alive for longer exposures to colder temperatures without too many cells exploding.

Harvest, Pressing, and Fermentation
Congratulations Canada on legalizing staplers.

The grapes are required to be naturally frozen on the vine before harvest, which usually doesn’t occur until December or January. (In British Columbia it may happen earlier, even in November.) Sometimes partial harvesting can occur in December before a later final harvest. If left hanging until February or March the fruit may be too dehydrated to be of use, or too much of it will be lost to the ground or predators. But if harvested too early, the grapes do not gain sufficient concentration and complexity. Sugars and acids and other solutes in the grape lower the freezing temperature of the juices quite a bit below that of pure water. When some of the juice freezes, the unfrozen juices are further concentrated—which further lowers the freezing temperature, just as mentioned before with intracellular concentration. Up to the point of harvest, the grape undergoes a process of successive partial freezes and thaws which continue to concentrate the sugars and other compounds and potential extracts.

When premonitions of the fateful time of harvest finally arrive, vintners painstakingly track the depths of the approaching chill, degree by degree, minute by minute. Canadian regulations require harvesting temperature to be at least -8° C/18° F. (Since 1982, German wine law requires at least -7° C/19° F). Ideal harvest temperatures are usually around -10° C to -13° C (14-9° F). If temperatures fall below -14° C (8° F) much of the tartaric acid content precipitates as potassium tartrate and too much of the water is frozen. Eyes are glued to continually updating reports from weather stations receiving data at different elevations and points in the region. To harvest at exact ideal temperatures often requires waiting until the coldest part of the day. What is darker and colder than the “darkest evening of the year?” The darkest middle of the night of the year.

Unfortunately human cells are not nearly as freeze-resistant as the vines. Harvest is usually accomplished by heavily gloved hands, although mechanical harvesters are becoming more common. It must be done effectively to reduce loss of the already greatly diminished crop, and efficiently: there is only a small window before the temperature changes, and all whilst one's vital areas and extremities are bundled to withstand the cold. The grapes must be wrangled from heavy bird netting. Often the precious brown clusters, some desiccated, some bearing perfect hardened round pellets, slip onto the ground rather than into the harvesting containers. I imagine it can be like literally losing your marbles.

Respite is far from sight once the harvest is over. Pressing, which can take many hours, must commence immediately and in cold conditions before too much thaw can occur and dilute the extract. Provincial regulations require the grapes to be pressed in a continuous process while the grapes are still frozen. Care must also be taken since friction from pressing generates heat. Pressing temperature is more important in determining final sugar content than original must density and usually ranges from -8 to -14° C (18-7° F).

Many different types of presses can be used, but basket presses are becoming more popular. Perhaps because they give a cleaner press than horizontal presses, or perhaps because they can be used in the field and are more flexible.

The collected juice is allowed to warm slightly when stored in tanks in order to aid settling and clarification, and centrifuging or rotary vacuum drum filters may also be used. Bentonite or other types of fining agents may be used and some winemakers choose to blend prior to fermentation.

The high concentration of sugar and other solutes causes a slow fermentation which arrests prematurely due to a combination of the high sugar concentration and accumulation of ethanol, acetic acid, various carboxylic acids, and other compounds. This produces a high residual sugar content. To achieve sufficient alcohol levels, winemakers can sometimes require two and a half times as much yeast as normal. The fermentation differs from table wine fermentation as the yeasts augment glycerol synthesis, which limits cytoplasmic water loss and provides osmotolerance (which protects them from the high sugar and solute levels), and also results in the formation of acetic acid, frequently increasing titratable acidity. Fermentation temperature, strain of yeast, and use of yeast acclimation will also have considerable effect. Inoculation with commercial strains of yeast is common as there are very few natural saccharomyces yeast cells left on the grapes after harvest.

Regulations require that the resulting juice must achieve a minimum of 32° Brix when measured after transfer to the fermentation vessel, and that the finished wine must be produced from a must that achieves a computed average of at least 35° Brix. At bottling, residual sugar levels must reach a minimum of 100 g/l (110 g/l in Nova Scotia), and actual alcohol content must be at a minimum of 7.0%. Chaptalization is not permitted, but Ontario regulations allow that sweet reserve (süssreserve) may be added if the minimum Brix level of the grapes used in the sweet reserve was 32° Brix at harvest, and it does not exceed 15% of the total volume of the wine.

Artificial methods of concentrating the sugar content of fresh grapes, grape juice, grape must or wine—including artificial refrigeration at a temperature below -4° C (25° F)—are prohibited. Additionally, tank cooling at a temperature below -4° C is prohibited during fermentation and cold stabilization prior to bottling. Unlike European regulations, which only allow addition of a total of 1 g/l citric acid in the finished wine, Canadian regulations permit several acids to a combined total of 4 g/l, as permitted by the Canada-EU Wine and Spirits Agreement. Acidification is usually unnecessary for Riesling, but may be practiced in certain vintages for other varieties.

Depending on a myriad of factors, a range of different outcomes are possible for icewine in aroma, structure, texture, and color. Alcohol content typically ranges around 10% and possible aromas span across a full range, from honeyed apple and lemon, to raisiny butter and spice, to peach and apricot, orange, litchi, mango and pineapple. It generally displays golden color of varying degrees, possibly attributable to a combination of juice concentration, caftaric acid oxidation, and the release of catechins on freezing. Notable producers include such wineries as Inniskillin, Pillitteri Estates, Reif Estates, Peller Estates, Pelee Estates, Jackson-Triggs, and Summerhill Pyramid. Dr. Karl Kaiser of Inniskillin has noted two major styles: a “fat” style with deeper color and a “slim” style, lighter in color and alcohol with more finesse and complexity of flavor and fruit profile. Some wineries also produce sparkling icewine, using the Charmat process, and some traditional method sparkling wines use icewine as dosage.

Markets and Regulations
Congratulations to Prime Minister Tim Horton on getting his double double.

The popularity of Canadian icewine grew greatly in recent years, predominantly due to the export market. In 1996, Québec-born Roger Provost, former director of international marketing for Courvoisier S.A. in France, started working for the Canadian wine conglomerate Vincor International (also now owned by the U.S. Constellation Brands), which represented Inniskillin. He made large efforts to target the Asia-Pacific market, in particular the duty-free travel retail market, and made Inniskillin’s Gold Label a highly successful luxury brand. Other wineries, such as Pillitteri Estates Winery in Niagara, initially forged more direct routes to the Asian market through individual regional agents. By 2012, the top ten export markets for Canadian icewine were China, South Korea, Singapore, Hong Kong, Taiwan, Japan, United States, United Kingdom, Malaysia and France. Volume exports totalled 222,716 liters valued at $15.5 million, with China accounting for $8.6 million. A telling indicator of icewine’s popularity is evidenced by the reports that in some Asian markets, at least half of the displayed products claiming to be Canadian icewine are not authentic Canadian products. Congratulations, Canada. One really cannot call something a luxury marketing success until an Asian population starts to fraudulently copy it.

Icewines generally range anywhere from CAD $25.00 to CAD $60.00 for a 375 ml bottle, but special bottles can easily sell for far more. Sparkling icewines are priced up to CAD $80.00. The high prices reflect the high risk nature of the venture. Apart from normal viticultural dangers such as mold during rainy spells, loss due to wind damage, etc., there are many icewine-specific difficulties. The longer hang time of the grape makes it easy prey for hungry animals whose desperation increases with the cold. Starling flocks can decimate a vineyard in one fell swoop. Maintenance and harvest conditions frequently belie Robert Frost’s “easy wind and downy flake,” as voracious wind and snow conditions can leave one wondering how the migrant workers of often Southeast Asian descent cope. And speaking of Frost, sudden dips in temperature require protection methods such as wind machines or aspersion. Unusually warm winters are equally feared, increasing risk of rain-related rots and other disease. Too much dehydration rendered by causes such as Botrytis cinerea could result in significantly decreased volume—or even grapes' inability to freeze due to sugar concentration. After all is said and done, yields can sometimes be as low as 5% of the crop. About 3.5 kg of Riesling grapes or 3 kg of Vidal grapes will produce a standard 375 ml bottle of icewine, which is six to seven times as much as what would be needed for table wine.

Yet is this worth a sum as ridiculous as $30,000 for a half bottle? If you are a Saudi Arabian mogul buying a Royal DeMaria Billy Myers Series 2000 Chardonnay Icewine, apparently so.

It is perhaps this popularity that compelled the Canadian government to introduce a federal standard for icewine early this year. Before this, the only icewine regulations were at a provincial level. This regulation unfortunately created an upset in Québec, where climates are more harshly frigid than Ontario or British Columbia and most icewine producers use what is called the “hammock” method, wherein grape clusters are clipped into hammock-like nets, left outdoors, and collected once the grapes reach sufficient concentration. Many Québecois vintners argue this method scientifically produces no difference in taste, even though it does not satisfy the new regulations’ requirement that the grapes be harvested “naturally frozen on the vine.”

Ice Cider (Cidre de Glace)
Congratulations, Jacques Poutine on becoming "president" of Canada.

Québec’s output of icewine is still only a fraction of the Niagara and Okanagan regions, but after icewine rose in popularity in the 1980s another frozen fruit fermentation beverage came to the fore: cidre de glace, or ice cider in English. The sophisticated and detailed nature of its cultivation and production deserves its own article, but it seems appropriate to make brief tribute while on the subject of winter-harvest alcohol.

The “Eastern Townships” of southeastern Québec is home to la Route des Vins, which extends from Bedford, Québec (about 10 miles north of the Vermont border) on the west, north to Farnham and east to Lac-Brome. The towns of Dunham and Frelighsburg, just east of Bedford, have claim to fame for several notable cidreries. It’s the area in which resides Christian Barthomeuf, the man credited as being the father of Québecois ice cider. After emigrating from France in the 1970s, he first focussed on winemaking before noticing the potential of the region’s apples for ice cider in 1989. By 1994 he was producing ice cider, amongst other ciders, for La Face Cachée de la Pomme, founded by François Pouliot. Pouliot’s enterprise entered full-scale commercial production in 2001, but in 2000 Barthomeuf departed to work as cider maker for a period of time for Domaine Pinnacle, owned by Charles Crawford. Since 2002, he has been producing his own line of ciders from a small orchard in Frelighsburg under the name Clos Saragnat. His expertise, coupled with his experimental and curious nature, continues to develop and evolve the Québec cider scene.

Over forty cidreries exist in Québec, but the vast majority—approximately 80%—of annual ice cider production is attributable to La Face Cachée de la Pomme and Domaine Pinnacle. In 2012, annual provincial production was estimated at over a million bottles worth about $20 million in retail. About one-third of the production is exported to Europe and Asia. As well, ice cider production is starting to become more popular in other parts of Canada, the U.S. and Europe.

The issue of freezing naturally on the plant is debated amongst ice cider makers, and two methods of production have evolved: cryoextraction and cryoconcentration. With cryoextraction, the method of production is similar to the making of icewine. Apples are left to freeze and concentrate their juices on the tree, and harvest can occur anytime from December through February, once the internal temperature of the apples reaches -8° C to -15° C (18-5° F). The frozen apples are pressed and the juice is fermented for 6-18 months. In the alternative method of cryoconcentration, the apples are harvested during the late fall and stored. When the weather becomes cold enough, the apples are pressed and their juices are left outside until much of the water content freezes, concentrating the remainder, which is then fermented. Many argue that the more intensive cryoextraction process creates a deeper, more complicated flavor, whereas others hold that the difference in taste is negligible when compared to the difference in labor, or that biochemical changes that occur in the apple in the fall make cryoconcentration preferable for certain varieties.

In December 2008, definition and specific standards for Québec ice ciders came into effect. The regulation defines “ice cider” as cider obtained from the fermentation of the juice of apples that has a pre-fermentation sugar content of not less than 30° Brix, achieved solely by natural cold, producing a finished product with a residual sugar content of at least 130 g/l and an actual alcoholic strength of 7-13% by volume. The regulations also dictate that chaptalization and the addition of alcohol or artificial flavors or colors are not allowed. Artificial cooling is only permitted at temperatures of greater than -4° C (25° F) and only for purposes of malic precipitation. Ice cider producers must cultivate the apples themselves, unless they possess a manufacturer’s license, in which case they can use a maximum of 50% of apples they do not grow themselves. Artificial infusion with carbon dioxide is permitted provided that the volume of dissolved carbon dioxide per volume of finished product is 1.5-2.5 or 3.5-5.5.

Following a natural approach has become common practice amongst certain boutique cidreries. Some choose to use only organic apples, to refrain from filtering or from warming or chilling the liquid in the tanks, and to abstain from the addition of commercial yeasts, sulfur, or chemical additives. As well, it is not unusual for some cider-makers to allow the cider to remain in the tanks on its lees for a period of time or to age the cider in oak casks.

Blends are more common than single-variety ciders, perhaps because blending facilitates attaining a balanced product as different varieties will reach different sugar, tartness, and tannin levels. In Québec, the majority of apples used are eating apples like McIntosh or its offspring Empire, unlike in Europe where the trend can be to use specific cider varieties such as Bulmer’s Norman, Tremlett’s Bitter, and Stembridge Cluster. Other varieties that can be included range from regional eating cultivars, such as the disease-resistant Liberty, Freedom, and Trent, to heirloom varieties such as Calville Blanc, Reinettes, Ashmead’s Kernel, and Esopus Spitzenburg. Using rare, unidentified wild varieties discovered by walking out into the middle of wooded areas in winter time, is a habit of Barthomeuf’s. It can take from 50 to more than 100 apples to produce a single 375 ml bottle of ice cider (and accordingly, it is priced similarly to icewine at CAD $20 to $60 a bottle).

Above: Christian Barthomeuf and top Canadian Sommelier Véronique Rivest at SOIF bar-à-vin

Conclusion
Congratulations Canada on getting 800 miles of paved road.

In my opinion, the only humans who don’t have a love-hate relationship with snow are the ones who don’t live where there is snow. Winter blows in and you wonder why you are living this far north. You step outside, and just breathing out causes icicles to form on body parts, the bargaining chip of “winter sports” no longer placates, and you start irrationally cursing your indifferent ancestors who probably knew the laws of equatorial physics, but instead of traveling further south, simply shrugged their snow-covered shoulders, politely grinned, took it and toqued it, bore it and bearded it, just as they complacently yet stubbornly obtained independence from the empire through painstaking patience.

But that is the true beauty of winter. It’s a beauty that is a hard-earned exercise in understanding and patience, much like the beauty of wine. The darkness and the quiet, an enveloping whiteness, the pristine untouched purity that comes from being the only warm-blooded mammal insane yet prepared enough to brave the snow and ice. It’s something one should be careful not to oversimplify, whether by reducing it to a mere status symbol or airport luxury gift item, by carelessness or dilution in processing, or by blindly tagging it to general climate stereotypes or a superficial concept of winter beauty. Icewine/cider making requires great care, time, and effort, both mental and physical, in using the natural elements of a region to create a balanced and integrated work of art. There are many times the winter is too much for some and shortcuts can create examples of both icewine and ice cider that are far less than, let us say, exemplary. But there will also be hard-earned cuvées that exhibit fresh crispness balanced with smooth concentrated flavor that exemplifies the true taste of winter. The embodiment of the trudge. The dedication and toil in striving for a loftier objective, in arriving at true perfection. To desire the taste of mysterious winter fruit, “lovely, dark, and deep,” but to realize there are miles to go before one sleeps. And miles to go before one sleeps.

With bannock bread and caribou eggs, the True North big and cold.
Oh Canada, we are on top. We're close to the North Pole.
Fermez la bouche. Mangez poutine.
Canada! A lovely winter dream.
Oh Canada, La La La La, La, Laaa.

-San Franciscans sing Canada’s "national anthem" with Rick Mercer on Talking to Americans, 2001

**Icewine grapes and press photos courtesy of Wine Country Ontario

Somm vs. Scientist: How Winespeak Relates to Chemspeak

Lisa Wong — Sun, 09 Jun 2013 13:10:00 GMT

The subject of wine bridges many different fields of study. Before developing a love for wine, I first acquired a love for science (albeit mostly due to the fact that appreciating science doesn’t have a legal age requirement), and when exposed to different disciplines or professions, one notices overlaps in terminology that, without clarification, can cause meanings to be lost in translation. The sommelier profession is no exception. As a former chemical researcher, I’m sometimes confused by discrepancies in the ways various terms are used in the sommelier community when compared to the scientific community. Some scientists might go so far as to call such rhetoric misnomer, but to me, it seems more like poetic license. I’m of the opinion that every profession should be allowed to develop its own vernacular based on its own distinct historical and etymological evolution. Should one criticize the singer who sings an unaccompanied vocalise marked a capella for not actually singing in the manner of the chapel? However, a certain amount of consistency between culinary and scientific usage is desirable, so that barriers to communication between sommeliers and people in the scientific wine-related community are not created. In the following text, I want to briefly elaborate on a few differences between winespeak and chemspeak, in particular, the concepts of oxidation/reduction and viscosity.

Oxidation and Reduction

The word "redox" comes from an abbreviation of “reduction-oxidation.” In present times, redox reactions relate to changes in states of hypothetical charge, and are explained through electron transfer. Electrons can be defined as small subatomic particles with negative charge; all atoms have electronsin their natural state. Reduction confusingly refers to chemical species (molecules, atoms, ions, etc.) “gaining” electrons. Oxidation is the opposite: it means species are “giving” or “losing” electrons. Here’s how I was taught to remember it:

OIL RIG
(oxidation is loss; reduction is gain)

One should note that the redox reaction is a concept designed to help explain phenomenon at a molecular level. It’s not literal description, and its conception predates certain scientific developments such as electronegativity theories. In other words, electrons, aren’t actually given and taken the way you can with apples or pennies.In the general sense of the words, oxidation and reduction are not separate reactions because where there is oxidation there is usually reduction. For one species to give another needs to take; oxidation and reduction happen at the same time. Hence the combination of the two terms into “redox”. When scientists refer to one without the other, they are usually focusing on one species, molecule or element that is important to the context, such as the oxidation of carbon or sulfur. In winespeak, the concepts are used in this way, oxidation referring to separate and different reactions than reduction. I find that’s not the part that confuses most people, however. What causes confusion is the fact that oxidation, despite its name, doesn’t necessarily have to have anything to do with oxygen anymore. But it did at one point.

Oxygen in the air (diatomic oxygen gas, O2) was discovered in the late 18th century (credited to either British clergymen Joseph Priestley or Swedish pharmacist Carl Wilhelm Scheele, depending on whom you ask), at which point French chemist Antoine Laurent de Lavoisier became very interested in its qualities. Lavoisier coined the word "oxygen" after the Greek terms for "becoming sharp" because for some reason he thought that the sharp taste of acids came from oxygen. He was wrong, but the word stuck. Lavoisier, however, correctly related oxygen to combustion reactions and the rusting of metal, or in other words, the creation of metal oxides. Oxides are chemical compounds that contain oxygen and one other element such as iron (e.g. ferric oxide, Fe2O3, associated with rust) and can be formed through reactions between the element and oxygen. Oxides can also undergo reactions to lose oxygen. Lavoisier and other early scientists noticed that certain metallic oxides could be heated to extract the metal itself and that they lost mass in this process. The oxide was being "reduced" to metal, and this is where the original concept of “reduction” came from. By today’s scientific definitions, oxygen is not the only oxidizing agent, oxidation does not have to include addition of oxygen, and reduction does not have to create a loss in mass. In a sense, the terms “oxidation”, “reduction”, and even “oxygen”, are themselves misnomers. Scientists later realized more accurate ways to describe these concepts and reactions, but the terms caught on, became entrenched, and nobody really wanted to change them. Etymological results of the process of history.

So where did the descriptor “oxidative” enter the etymological process for sommeliers? From a specific field of chemistry - organic chemistry. Organic compounds are those that contain carbon, and wine, like anything else composed from once-living matter, is full of them. Organic chemistry often refers to organic compounds as being “oxidized” when the carbon in the compound loses electrons to oxygen, such as in the oxidation of alcohols to aldehydes, carboxylic acids and ketones. These reactions result in an increasing number of bonds between carbon and oxygen, and the carbon loses electrons to oxygen by the creation of these additional bonds. Hence, it is oxidized.

These oxidation reactions can have different relationships to oxygen than the reactions that involve metal oxides. For example, when ethanol (CH3-CH2-OH), which is the chemical alcohol in vernacular alcohol, undergoes oxidation it becomes ethanal (CH3-CHO), more commonly known as acetaldehyde. In this reaction, more oxygen is not added to the molecule, but instead two hydrogen are lost and the number of bonds between carbon and oxygen increased. The reaction is considered an oxidation even though reactions with additional oxygen may not be directly involved. With wine, the conversion of ethanol to acetaldehyde often results due to the presence of oxygen in the form of O2, but not necessarily due to the O2 reacting directly with the ethanol. Under many conditions, O2 can oxidize phenolic compounds in the wine to form more reactive substances like hydrogen peroxide, which can then undergo oxidation reactions with either ethanol or other phenolic or non-phenolic compounds. The products of these reactions can undergo further oxidation reactions to create different compounds such as acids and esters, like acetic acid or ethyl acetate, and the reactions can continue, on and
on. Wine, like language, has the capacity to evolve perpetually.

So what does the term "oxidation" mean in an aromatic sense? Technically, by scientific terms, oxidation by O2 is almost always happening to some component of the wine at some level as long asthe wine isin contact with some amount of O2. The sense of perceptible “oxidation” that sommeliers are concerned with relates to a wide range and diversity of aromas that arise due to levels of acetaldehyde and/or other products of oxidation reactions reaching different sensory thresholds. Usually the presence of a high degree of these compounds is considered a fault, but a certain degree may be considered desirable and even indicative of classic styles. Most of the time, the presence of O2 is the key component in initiating these oxidation reactions, and therefore, sommeliers are not being inaccurate when they link certain aromas to the presence of O2. However, sommeliers should remember that many “oxidative” aromas do not develop just because the wine was aged or just because it was exposed to too much air. What matters are the stage, type, and/or degree of certain redox reactions caused by exposure to O2. These aspects depend on winemaking factors such as the amount of O2, the duration and timing of exposure, whether there is exposure or absence at a specific points in the process, and very importantly, what chemical compounds, as well as catalysts and micro-organisms, are present at the time (which relates to viticultural factors as well). It should also be kept in mind that wine that does not smell “oxidative” has also likely been exposed to O2 at some point, and such
exposure is usually desired at certain points in making any wine.

This brings us to the term "reduction." What gets a little confusing is when no distinction is made between reference to “reduction” in the sense of there being an absence of oxygen, and “reduction” in the sense of “reduced” sulfur, where sulfur is in a state where it is gaining more electrons when compared to another state. The two are related: in winemaking, reduced forms of sulfur can result in “reductive conditions” where exposure to O2 is limited in some way (but keep in mind, reductive conditions do not necessarily have to relate to O2 as the controlling factor). Therefore, for sommeliers, the indicator of this kind of vinification is often a smell that is associated with sulfur compounds. Sulfates contain sulfur bonded to four oxygen atoms (SO42-), and are considered oxidized forms of sulfur. In other words, the sulfur is losing electrons to the oxygen. Sulfites only have three oxygen atoms (SO32-), and can be considered “reduced” compared to sulfates, which have more oxygen taking electrons from the sulfur, or oxidized in comparison to compounds that contain sulfur that is not bonded to oxygen. Sulfur dioxide (SO2) in its molecular form is technically a sulfur oxide and not a sulfite, but it is often lumped together with sulfites because it converts to sulfites in the presence of aqueous base, or water. A certain amount of molecular SO2 can smell like matchstick, and some wine people associate SO2 with “reductive” wine conditions because usually it is added to the system intentionally as a method of reducing oxidative aromas. Technically, SO2 does not prevent oxidation so much as the smell of it, or the stage of it. It doesn’t really prevent O2 from reacting with components in the wine, and while it can react with hydrogen peroxide to partially prevent further oxidation reactions, its more important role is to bind to the smelly products of wine oxidation like acetaldehyde.

What is most often meant in winespeak by “reduced” sulfur forms are volatile compounds where sulfur is not bonded to oxygen, such as sulfides and thiols (mercaptans). The most notable sulfide in wine is hydrogen sulfide (H2S), which can produce rotten egg smell and can be detected at very low quantities. H2S can be created at different points in the winemaking process, such as during fermentation or postfermentation aging on the lees. Factors such as levels of elemental sulfur, SO2, organic sulfur-containing compounds, nitrogen limitation, and vitamin deficiency can all effect sulfide production. Sulfides other than H2S and disulfides in which two sulfur atoms are bonded together can produce off-putting odors like rotting cabbage or burnt rubber. In general, higher amounts of these sulfides are needed to reach sensory thresholds than for H2S and thiols, but they can be difficult to remove and some disulfides can revert to even worse smelling thiols in bottle. H2S may be treated with techniques like copper, but left untreated, H2S may also form thiols.

Another name for thiols is mercaptans. “Mercaptan” was a word coined by a Dutch scientist in 1834, because to him the compounds "captured" mercury (really, it just reacted vigorously). This term is still in use scientifically, but many use the term “thiols” as it is more in line with the universal standards of IUPAC nomenclature (see note below). Thiols are basically compounds with carbon bonded to sulfur and hydrogen, a sufhydryl group (-C-SH), and can occur in wines due to a myriad of factors in the winemaking process. Like sulfides, many of these compounds are described as having aromas such as rubber, burnt rubber, rotting cabbage, garlic, and onion.It should be noted that there are other types of sulfur molecules, like thioethers, which may give reductive smells and are not classified as thiols. Also not all thiols, sulfides and sulfur compounds give off scent or give unpleasant or unwanted scent. Some can contribute to a coffee-like smell, and others can smell like grapefruit. As well, there are many aromas that can result from “reductive” winemaking conditions that do not involve sulfur, and just like with oxidation, the presence of reductive aromas are not necessarily a fault. It is the nature and degree of the aroma created by “reductive” processes that will determine this.

The terms “oxidative” and “reductive” have already become commonplace descriptors for wine aromas. They are more complicated terms than other wine descriptors - the ideas that are conjured from the use of “oxidative” as a wine descriptor are not as simple as those evoked by descriptors like “bruised apple” - but the beauty of wine can lie within its complexity. As scientific knowledge about wine increases and this knowledge is imparted on more sommeliers, the aromas, tastes and textures that result from redox reactions may become more defined, along with the terms used to describe them. I expect, and desire, that both sommelier and scientific fields will evolve together.

Viscosity

Many sommeliers find it useful to swirl or coat the sides of the glass with wine and observe the “tears” or “legs.” Some refer to this as analyzing the “viscosity” of a wine, the purpose being to get information about alcohol and sugar levels, and perhaps also some information about extraction. In everyday usage, people relate the word “viscosity” with how thick a fluid is. The term originates from the Latin word for mistletoe, viscum, because mistletoe berries were used to make a viscous, gluey birdlime to trap birds. In science, however, the concept of viscosity, which can be defined as a resistance to flow, relates to fluid motion and fluid dynamics, which are very complicated fields that factor in molecular
considerations, thermodynamics, kinematics, and inertial forces. All wine possesses scientific viscosity, and it is true that viscosity can be related to alcohol and sugar levels in the wine, but many many other factors can affect viscosity. Observing minute differences in the definition of the legs of a wine may not always be an accurate method of assessing these relationships which are not always linear, particularly because the composition of different wines are so complex.

However, because some information is usually evident from examining the legs and the sommelier is not necessarily concerned with assessing fractional differences on a purely visual level, I see no harm in using the word “viscosity” to explain to customers and other professionals why the sommelier is drawing certain inferences from the legs. The practice itself is not unscientific to me. A sommelier makes assessments by drawing from experience, from trial and error in a multitude of different circumstances, and such expertise and use of human faculties has the potential to result in accuracy greater than deduction from an accumulation of isolated information from different experiments from different laboratories.
One thing that should be noted is that tears or legs in a wine do not form because of their scientific viscosity. If you put molasses in a wine glass, it will not form legs. Why? Because wine forms legs due to the different surface tensions and vapour pressures between alcohol and water. This effect has been called the Marangoni or Gibbs-Marangoni effect. Fluids will move from a lower surface tension to a higher surface tension, otherwise known as a tension gradient. Ethanol has lower surface tension than water. When you swirl and coat the sides of the glass with wine, the ethanol (which has greater vapour pressure than water) evaporates from this coating more quickly than from the wine in the glass, causing the surface tension of the liquid on the sides of the glass to increase due to there being less ethanol. This creates a tension gradient between the coating on the sides and the pool of wine in the glass. Wine is drawn up into the coating from the pool and the alcohol continues to evaporate. The water in the wine starts to draw together into droplets at the top, due to cohesion, and the droplets fall down the sides of the glass under the influence of gravity.

Accordingly, there are many factors that can affect the appearance of the legs such as temperature, the liquid-air interface, the condition and shape of the glass, and variables regarding the swirling or coating. Again, I bring this up simply to highlight the difference in mindset between a scientist and a sommelier, and not to denigrate the practice as obtaining no useful information, especially since the sommelier does not use this as their only input about the wine. Also, in my mind, the act of swirling the wine and observing the legs can provide a traditional aesthetic purpose, and aesthetics and tradition are more functional for sommeliers than scientists. I once had a wine expert ask me what I thought of the wine, “viscously-speaking”. The scientist (and grammaticist) in me wanted to reply that one cannot speak with viscosity. But the wine-lover in me instead just said, “It has nice legs.”

Some additional facts:

If you think “redox” is a strange word, how about “phlogiston”? Phlogiston, a term with origins in alchemy in the late 1600s, was thought to be an element that was released from objects during combustion, and was the precursor theory explaining certain oxidation reactions before Lavoisier’s influence.
Even though redox is usually explained through electron transfer today, it was once also explained as the loss or gain of oxygen, and also conversely, the gain and loss of hydrogen (electron “transfer” happens in all of these types of reactions, and is therefore the most all-encompassing method of explanation).
“Redox potential" can be defined in different ways, but in aqueous solutions (solutions where the solvent is water, like wine) it's a measure of the tendency of the solution to gain or lose electrons when a new chemical species is introduced, and here's the neat thing: it's measured in volts, like with electricity and batteries because electrons are species with charge. Increasing oxygen exposure through techniques like racking can often raise a low redox potential number.
Thiol is the preferred suffix for organic compounds with a carbon-bonded sulfhydryl groups used in the IUPAC nomenclature method (universal rules for naming chemicals) and it's used just like "ol" is used for alcohols. In chemistry, an alcohol is a compound with an oxygen bonded to hydrogen, (a hydroxy group, -OH). Ethanol is CH3-CH2-OH. Ethanethiol is CH3-CH2-SH. It can produce smells like burnt match.
The Marangoni or Gibbs-Marangoni Effect is named after Carlo Marangoni who first studied it in the 1870s. James Thomson explained the phenomenon in his 1855 paper, "On certain curious Motions observable at the Surfaces of Wine and other Alcoholic Liquors". (Sounds like a fun thesis!)

Lisa N.S. Wong (B.Sc. (Hons), J.D.), majored in chemistry at Queen's University and has been employed as a researcher at such institutions as the Atomic Energy of Canada Ltd., Chalk River Laboratories, and National Research Council Canada, Steacie Institute for Molecular Sciences. She afterward obtained her J.D. from Osgoode Hall Law School (call to the bar, 2009), and has practiced intellectual property law and commercial litigation at a leading Bay Street firm. She is currently completing the sommelier intensive at the International Culinary Centre, California campus.