On Food And Cooking Part 96

Selecting Desirable Volatiles Distillers must therefore control the composition of the distilled liquid. They do this by subdividing the vapor into fractions that are more and less volatile, and collecting mainly the fraction that is richest in alcohol. The fraction more volatile than alcohol, often called the "heads" or "foreshots" because it evaporates earlier than alcohol, includes toxic methanol, or wood alcohol, and acetone. The fraction that's less volatile than alcohol, the "tails" or "feints," includes a host of aromatic substances that are desirable. Among these "congeners" (substances that accompany alcohol) are esters, terpenes, and volatile phenolics, along with some substances that are desirable in limited amounts. The most notable of the latter are the "higher" alcohols, whose long, fat-like chains can give spirits a full, almost oily body, but also contribute a p.r.o.nounced harsh flavor and unpleasant aftereffects. They're often called Distillers must therefore control the composition of the distilled liquid. They do this by subdividing the vapor into fractions that are more and less volatile, and collecting mainly the fraction that is richest in alcohol. The fraction more volatile than alcohol, often called the "heads" or "foreshots" because it evaporates earlier than alcohol, includes toxic methanol, or wood alcohol, and acetone. The fraction that's less volatile than alcohol, the "tails" or "feints," includes a host of aromatic substances that are desirable. Among these "congeners" (substances that accompany alcohol) are esters, terpenes, and volatile phenolics, along with some substances that are desirable in limited amounts. The most notable of the latter are the "higher" alcohols, whose long, fat-like chains can give spirits a full, almost oily body, but also contribute a p.r.o.nounced harsh flavor and unpleasant aftereffects. They're often called fusel oils. fusel oils. ( (Fusel is the German for "rotgut.") A small dose of fusel oils gives a distilled alcohol character; too much makes it unpleasant. is the German for "rotgut.") A small dose of fusel oils gives a distilled alcohol character; too much makes it unpleasant.

Concentration by FreezingDistillation is the most common way of making concentrated alcohols, but it's not the only way. Freezing also concentrates the alcohol in fermented liquids, by causing the water to form a ma.s.s of solid crystals from which an alcohol-enriched fluid can be drained. (Alcohol freezes at 173F/114C, far below water's freezing point of 32F/0C.) In the 17th century, Francis Bacon noted Paracelsus's claim that "if a gla.s.s of wine be set upon a terrace in bitter frost, it will leave some liquor unfrozen in the center of the gla.s.s, which excelleth spiritus vini spiritus vini [spirit of wine] drawn by fire." The nomads of central Asia apparently applied "freezing-out" to their alcoholic mare's milk, [spirit of wine] drawn by fire." The nomads of central Asia apparently applied "freezing-out" to their alcoholic mare's milk, koumiss, koumiss, and European settlers in North America made apple brandy - applejack - in the same way. Freezing-out produces a different kind of concentrated alcohol. There's no heating step that alters the aroma, and unlike distillation it retains and concentrates the sugars, savory amino acids, and other nonvolatile substances that contributed to the original liquid's taste and body. and European settlers in North America made apple brandy - applejack - in the same way. Freezing-out produces a different kind of concentrated alcohol. There's no heating step that alters the aroma, and unlike distillation it retains and concentrates the sugars, savory amino acids, and other nonvolatile substances that contributed to the original liquid's taste and body.

Purity and Flavor The best indication of how strongly flavored a distilled alcohol will be is the percentage of alcohol in the liquid immediately after distillation, before it's further treated by aging and/or dilution with water to its final strength (see box, p. 765). The higher the alcohol content to which it's distilled, the purer a mixture of alcohol and water it is, the lower the proportion of fusel oils and other aromatics, and so the more neutral the flavor. Vodkas are usually distilled to 90% alcohol or more; brandies and flavorful malt and corn whiskies to 6080%. Crudely distilled moons.h.i.+ne is only 2030% alcohol, and therefore harsh and even hazardous. The best indication of how strongly flavored a distilled alcohol will be is the percentage of alcohol in the liquid immediately after distillation, before it's further treated by aging and/or dilution with water to its final strength (see box, p. 765). The higher the alcohol content to which it's distilled, the purer a mixture of alcohol and water it is, the lower the proportion of fusel oils and other aromatics, and so the more neutral the flavor. Vodkas are usually distilled to 90% alcohol or more; brandies and flavorful malt and corn whiskies to 6080%. Crudely distilled moons.h.i.+ne is only 2030% alcohol, and therefore harsh and even hazardous.

Pot or Batch Distillation: Selecting Volatiles by Time There are two ways for distillers to separate the vapor into undesirable heads, somewhat desirable tails, and the desirable main run of alcohol. The original way, and the way that is still used for many of the finest liquors, is separation in a simple pot still by There are two ways for distillers to separate the vapor into undesirable heads, somewhat desirable tails, and the desirable main run of alcohol. The original way, and the way that is still used for many of the finest liquors, is separation in a simple pot still by time. time. It can take 12 hours or more for a batch of beer or wine to be heated close to the boil and then distilled. The very volatile head vapors come off first, followed by the main alcohol-rich run, and then the less volatile fusel-oil tails. So the distiller can divert the initial vapors, collect the desirable main run in a different container, and then divert the late vapors again. In practice, distillers repeat the pot distillation, the first pa.s.s giving spirits with 2030% alcohol, and the second 5070%. It can take 12 hours or more for a batch of beer or wine to be heated close to the boil and then distilled. The very volatile head vapors come off first, followed by the main alcohol-rich run, and then the less volatile fusel-oil tails. So the distiller can divert the initial vapors, collect the desirable main run in a different container, and then divert the late vapors again. In practice, distillers repeat the pot distillation, the first pa.s.s giving spirits with 2030% alcohol, and the second 5070%.

The structures of several different alcohols. Methanol is a poison because our bodies convert it into formic acid, which acc.u.mulates and damages the eyes and brain. Ethanol is the main alcohol produced by yeasts. Butyl and amyl alcohols are two of the "higher," or longer-chain alcohols. When concentrated by distillation, they contribute an oily consistency to spirits thanks to their fat-like hydrocarbon tails.

Continuous Distillation: Selecting Volatiles by Position The second way in which distillers can separate the desirable volatiles from the rest is by their The second way in which distillers can separate the desirable volatiles from the rest is by their position position in a column still, an elongated chamber developed by French and British distillers during the Industrial Revolution. In a column still, the starting wine or beer is fed into the column from the top, and the column is heated from the bottom with steam. The bottom of the column is therefore the hottest region, the top the coolest. Methanol and other low-boiling substances remain vaporized throughout all but the very top of the column, while fusel oils and other aromatics with high boiling points will condense on collection plates at hotter positions toward the bottom of the column, and alcohol will condense - and can be collected - at an intermediate point. The advantage of the column still is that it can be operated continuously and without the necessity of close monitoring; the disadvantage is that it offers less opportunity than the pot still for the distiller to control the composition of the distillate. When two or more columns are run together in series, they're capable of producing a neutral distillate that is 9095% alcohol. in a column still, an elongated chamber developed by French and British distillers during the Industrial Revolution. In a column still, the starting wine or beer is fed into the column from the top, and the column is heated from the bottom with steam. The bottom of the column is therefore the hottest region, the top the coolest. Methanol and other low-boiling substances remain vaporized throughout all but the very top of the column, while fusel oils and other aromatics with high boiling points will condense on collection plates at hotter positions toward the bottom of the column, and alcohol will condense - and can be collected - at an intermediate point. The advantage of the column still is that it can be operated continuously and without the necessity of close monitoring; the disadvantage is that it offers less opportunity than the pot still for the distiller to control the composition of the distillate. When two or more columns are run together in series, they're capable of producing a neutral distillate that is 9095% alcohol.

Pot distillation. As wine or beer is gradually heated, the composition of its vapors changes, with very volatile substances evaporating first, less volatile substances later. The distiller diverts early and late vapors with their undesirable volatiles, and collects the "main run," rich in alcohol and desirable aromas.

Continuous distillation in a column still. The plates in each column are hottest at the steam input and coolest at the other end. Substances with low boiling points, including alcohol, are concentrated in the vapor that leaves the first column and rises in the second, and the alcohol-rich fraction is collected at a particular position in the second column.

Maturation and Aging Fresh from the still, distilled liquors are as colorless as water, or "white." They're also rough and harsh, so all are matured for weeks or months to allow the various components to react with each other, form new combinations, and become less irritating. From this point, the spirits are handled differently according to the kind of product they're meant to become. "White" spirits, including vodka and eaux de vie made from fruits, are not aged; they may be flavored, then adjusted to the proper alcohol content by the addition of water, and bottled. "Brown" spirits, including brandies and whiskies, are so called because they're aged in wood barrels, from which they derive a characteristic tawny color and complexity of flavor. (Some brown spirits may be colored with caramel instead.) Spirits may be barrel-aged for anything from a few months to decades, during which their flavor changes considerably. Fresh from the still, distilled liquors are as colorless as water, or "white." They're also rough and harsh, so all are matured for weeks or months to allow the various components to react with each other, form new combinations, and become less irritating. From this point, the spirits are handled differently according to the kind of product they're meant to become. "White" spirits, including vodka and eaux de vie made from fruits, are not aged; they may be flavored, then adjusted to the proper alcohol content by the addition of water, and bottled. "Brown" spirits, including brandies and whiskies, are so called because they're aged in wood barrels, from which they derive a characteristic tawny color and complexity of flavor. (Some brown spirits may be colored with caramel instead.) Spirits may be barrel-aged for anything from a few months to decades, during which their flavor changes considerably.

The extraction, absorption, and oxidation processes that take place during barrel aging result in the development of a mellow, rich flavor (p. 720). And the barrel allows both water and alcohol to evaporate from the spirits, thus concentrating the remaining substances. A barrel may lose several percent of its volume per year; that portion is called "the angels' share," and it may approach half the barrel volume after 15 years.

Final Adjustments When spirits are judged ready for bottling, they're usually blended to obtain a consistent flavor, and diluted with water to the desired final alcohol content, in the neighborhood of 40%. Small quant.i.ties of other ingredients may be added to fine-tune the flavor and color; these include caramel coloring, sugar, a water extract made by boiling wood chips (the When spirits are judged ready for bottling, they're usually blended to obtain a consistent flavor, and diluted with water to the desired final alcohol content, in the neighborhood of 40%. Small quant.i.ties of other ingredients may be added to fine-tune the flavor and color; these include caramel coloring, sugar, a water extract made by boiling wood chips (the boise boise of Cognac and Armagnac), and wine or sherry (blended U.S. and Canadian whiskeys). of Cognac and Armagnac), and wine or sherry (blended U.S. and Canadian whiskeys).

Chill-Filtering Many spirits are Many spirits are chill-filtered chill-filtered: chilled to below the freezing point of water, and then filtered to remove the cloudy material that forms. The substances that form the cloud are poorly soluble fusel oils and volatile fatty acids from the original spirits, and a variety of similar substances extracted from the barrel. Their removal prevents the spirits from clouding when the drinker chills them or dilutes them with water, but it also removes some flavor and body, so some producers choose not to chill-filter. Clouding does not occur in spirits with more than about 46% alcohol, so such undiluted "cask-strength" spirits are often not chill-filtered. (Some spirits cloud spectacularly; see p. 771).

Serving and Enjoying Spirits Crystal Decanters Can Be Hazardous High-alcohol spirits are biologically and chemically stable and can be kept for years without spoiling. One traditional and decorative way of storing them has been the decanter made of gla.s.s crystal, which derives its weight and appearance from the element lead. Unfortunately, lead is powerfully toxic to the nervous system, and readily leaches from crystal into spirits and other acidic liquids. Old decanters that have been used many times have been preextracted and are safe to use; new ones should either be pretreated to remove lead from the inner surfaces, or only used for serving, not storing. High-alcohol spirits are biologically and chemically stable and can be kept for years without spoiling. One traditional and decorative way of storing them has been the decanter made of gla.s.s crystal, which derives its weight and appearance from the element lead. Unfortunately, lead is powerfully toxic to the nervous system, and readily leaches from crystal into spirits and other acidic liquids. Old decanters that have been used many times have been preextracted and are safe to use; new ones should either be pretreated to remove lead from the inner surfaces, or only used for serving, not storing.

Concentrated Alcohol: Proof ProofThe term proof proof is sometimes used to designate the alcoholic content of distilled liquors. In the United States, the proof designation is just about double the percentage by volume of alcohol, so that 100 proof, for example, designates 50% alcohol. (The proof number is slightly more than double the percentage, because alcohol causes a volume of water to contract on mixing.) The term is sometimes used to designate the alcoholic content of distilled liquors. In the United States, the proof designation is just about double the percentage by volume of alcohol, so that 100 proof, for example, designates 50% alcohol. (The proof number is slightly more than double the percentage, because alcohol causes a volume of water to contract on mixing.) The term proof proof comes from a 17th century test for proving the quality of spirits that involved moistening gunpowder with the spirits, and then putting a flame to it. If the gunpowder burned slowly, the spirits were at proof; if it spluttered or burst into flame, they were under or over proof respectively. comes from a 17th century test for proving the quality of spirits that involved moistening gunpowder with the spirits, and then putting a flame to it. If the gunpowder burned slowly, the spirits were at proof; if it spluttered or burst into flame, they were under or over proof respectively.

The Flavors of Spirits Spirits are served at temperatures ranging from ice cold (Swedish Spirits are served at temperatures ranging from ice cold (Swedish aquavit aquavit) to steaming hot (Calvados). To appreciate nuances of flavor, they're best served at room temperature, and if necessary warmed in the hands. Their aroma is intense, so much so that it can be just as enjoyable to sniff as to sip; Scotch lovers call this nosing. nosing. At distilled strengths, alcohol has an irritating and then numbing effect on the nose that is accentuated at high temperatures. To reduce the interference of alcohol and bring out more delicate aromas, connoisseurs often dilute whiskies with good-quality water to 30% or 20% alcohol. Different kinds of spirits have very different flavors, which derive from the original ingredient - grape or grain - from the yeasts and fermentation, from the prolonged heat of distillation, and from contact with wood and the pa.s.sage of time. Spirits with a high fusel oil content have an unctuous quality in the mouth, while more neutral spirits give a cleansing, drying effect. The aromas of spirits often persist in the mouth long after the liquid itself has been swallowed. At distilled strengths, alcohol has an irritating and then numbing effect on the nose that is accentuated at high temperatures. To reduce the interference of alcohol and bring out more delicate aromas, connoisseurs often dilute whiskies with good-quality water to 30% or 20% alcohol. Different kinds of spirits have very different flavors, which derive from the original ingredient - grape or grain - from the yeasts and fermentation, from the prolonged heat of distillation, and from contact with wood and the pa.s.sage of time. Spirits with a high fusel oil content have an unctuous quality in the mouth, while more neutral spirits give a cleansing, drying effect. The aromas of spirits often persist in the mouth long after the liquid itself has been swallowed.

Some Popular Distilled SpiritsThe alcohol content after distillation is an indicator of how much flavor is carried over from the base wine or beer to the spirits. The higher the alcohol content, the lower the content of other aromatics and the more neutral the flavor.

Kinds of Spirits Distilled spirits are made all over the world from all kinds of alcoholic liquids. Here are brief descriptions of the more prominent.

Brandies Brandies are spirits distilled from grape wine. The two cla.s.sic brandies are Cognac and Armagnac, the first named for a town and the second for a region in southwestern France, each not far from Bordeaux. Both are made from neutral white grapes (mainly Ugni blanc) that are casually fermented into wine, and the wines distilled between harvest and mid-spring (the best brandies are distilled first; as the wine sits, it loses esters and develops volatile acidity and off-aromas). Cognac is double-distilled from the wine with its yeast lees to an alcohol content of about 70%, most Armagnac single-distilled without yeast in a traditional column still to about 55%. Each is then aged in new French oak barrels for a minimum of six months; some Cognacs are aged for 60 years or more. Before bottling, each is diluted to about 40% alcohol and may be adjusted with sugar, oak extract, and caramel. Cognac has a fruity, flowery character thanks to the distillation of esters from the wine yeasts. Armagnac is relatively rough and complex thanks to its higher content of volatile acids; it's said to have a prune-like aroma. With long aging, both develop a prized Brandies are spirits distilled from grape wine. The two cla.s.sic brandies are Cognac and Armagnac, the first named for a town and the second for a region in southwestern France, each not far from Bordeaux. Both are made from neutral white grapes (mainly Ugni blanc) that are casually fermented into wine, and the wines distilled between harvest and mid-spring (the best brandies are distilled first; as the wine sits, it loses esters and develops volatile acidity and off-aromas). Cognac is double-distilled from the wine with its yeast lees to an alcohol content of about 70%, most Armagnac single-distilled without yeast in a traditional column still to about 55%. Each is then aged in new French oak barrels for a minimum of six months; some Cognacs are aged for 60 years or more. Before bottling, each is diluted to about 40% alcohol and may be adjusted with sugar, oak extract, and caramel. Cognac has a fruity, flowery character thanks to the distillation of esters from the wine yeasts. Armagnac is relatively rough and complex thanks to its higher content of volatile acids; it's said to have a prune-like aroma. With long aging, both develop a prized rancio rancio ("rancid") character from the transformation of fatty acids into methyl ketones, which also provide the distinctive aroma of blue cheese(p. 62). ("rancid") character from the transformation of fatty acids into methyl ketones, which also provide the distinctive aroma of blue cheese(p. 62).

Less renowned brandies are made elsewhere in France and throughout the world in a variety of ways, from the industrial to the artisa.n.a.l. Especially interesting are brandies distilled from more distinctive grape varieties than the purposely neutral Ugni blanc.

Eaux de vie, Fruit Alcohols, White Alcohols These are various terms that are less confusing than their synonym "fruit brandy": they name spirits that are distilled from fermented fresh fruits other than grapes. Unlike true "burned wines," which offer a complicated, transformed wineyness, eaux de vie capture and concentrate the distinctive essence of the fruits from which they're made, so they can be savored almost pure rather than in their flesh. France, Germany, Italy, and Switzerland are especially noted for their fine fruit alcohols. Some popular examples are apple (Calvados), pear (Poire Williams), cherry (Kirsch), plum (Slivovitz, Mirabelle, Quetsch), and raspberry (Framboise); less widely known are apricot (French Abricot), figs (North African and Middle Eastern These are various terms that are less confusing than their synonym "fruit brandy": they name spirits that are distilled from fermented fresh fruits other than grapes. Unlike true "burned wines," which offer a complicated, transformed wineyness, eaux de vie capture and concentrate the distinctive essence of the fruits from which they're made, so they can be savored almost pure rather than in their flesh. France, Germany, Italy, and Switzerland are especially noted for their fine fruit alcohols. Some popular examples are apple (Calvados), pear (Poire Williams), cherry (Kirsch), plum (Slivovitz, Mirabelle, Quetsch), and raspberry (Framboise); less widely known are apricot (French Abricot), figs (North African and Middle Eastern Boukha Boukha), and watermelon (Russian Kislav Kislav).

A single bottle of eau de vie may represent from 10 to 30 lb/4.513.5 kg of the fruit. Fruit alcohols are generally double-distilled to about 70% alcohol and are not aged in barrels - hence their lack of color - because their point is to concentrate the fruit's own flavor into an intense, full, but pure essence. One prominent exception to this rule is Calvados, an apple eau de vie that is distilled in Brittany from a blend of varieties, some too sour or bitter for eating. The apples are slowly fermented into cider over the course of several cool weeks in the autumn, and the cider is then distilled in either pot or column stills, depending on the district. The distillate is then matured in old barrels for a minimum of two years. Slivovitz, a Balkan plum alcohol, is also barrel-aged.

Whiskies and Whiskeys Whiskies (United Kingdom) and whiskeys (elsewhere) are spirits that have been distilled from fermented grains, mainly barley, maize, rye, and wheat, and then aged in barrels. The term comes from a barley distillate of medieval Britain, but is now applied to largely maize distillates in the United States and Canada, and mixed grain distillates in many countries. Whiskies (United Kingdom) and whiskeys (elsewhere) are spirits that have been distilled from fermented grains, mainly barley, maize, rye, and wheat, and then aged in barrels. The term comes from a barley distillate of medieval Britain, but is now applied to largely maize distillates in the United States and Canada, and mixed grain distillates in many countries.

Scotch and Irish Whiskies There are three kinds of Scotch whisky. One, There are three kinds of Scotch whisky. One, malt whisky, malt whisky, is made in the Highlands and islands entirely from malted barley. It's distilled twice in pot stills to about 70% alcohol, and has a strong, distinctive flavor. Another, is made in the Highlands and islands entirely from malted barley. It's distilled twice in pot stills to about 70% alcohol, and has a strong, distinctive flavor. Another, grain whisky, grain whisky, is less flavorful and less costly; it is made in the lowlands from various cereals and just a small portion (1015%) of malted barley to convert their starches into sugars, and distilled in a continuous still to a neutral 95% alcohol. The third and most common is a blend of malt and grain whiskies, with grain whisky accounting for 4070%. Such blending began in the 1860s for economic reasons, and turned out to produce a milder, more widely appealing drink just in time to replace brandy when the insect scourge phylloxera devastated European vineyards in the 1870s and 1880s. This is when Scotch developed its international reputation. Today, Scotch connoisseurs prize the distinctive "single-malt" whiskies produced by the few remaining small distillers of all-malt whisky. is less flavorful and less costly; it is made in the lowlands from various cereals and just a small portion (1015%) of malted barley to convert their starches into sugars, and distilled in a continuous still to a neutral 95% alcohol. The third and most common is a blend of malt and grain whiskies, with grain whisky accounting for 4070%. Such blending began in the 1860s for economic reasons, and turned out to produce a milder, more widely appealing drink just in time to replace brandy when the insect scourge phylloxera devastated European vineyards in the 1870s and 1880s. This is when Scotch developed its international reputation. Today, Scotch connoisseurs prize the distinctive "single-malt" whiskies produced by the few remaining small distillers of all-malt whisky.

Whisky makers produce beer, omitting the hops, and then distill it, yeasts and all. The distillate is aged in used oak barrels for a minimum of three years, then diluted with water to around 40% alcohol, and is usually chill-filtered. Scotch whisky owes its special flavor largely to the barley malt. Malt whiskies from Scotland's west coast have a unique, smoky flavor that comes from the use of peat fire for drying the malt, and peaty water for mas.h.i.+ng the grain before fermentation. Peat, the mat of decaying and decayed vegetation that once was the cheapest fuel available in swampy areas of Britain, contributes volatile organic molecules to the brew that find their way into the distillate.

Most Irish whisky is made from a mixture of about 40% malted and 60% unmalted barley. For this reason, and because it is pot-distilled twice and then again in a column still, Irish whisky is milder than malt Scotch and even some Scotch blends.

American and Canadian Whiskeys North American whiskeys are produced mainly from the New World's indigenous grain, maize. The most prominent corn whiskey is bourbon, which is named for a county in Kentucky where maize grew well in colonial times, and where there was abundant water for both mas.h.i.+ng the grains and cooling the distillate. North American whiskeys are produced mainly from the New World's indigenous grain, maize. The most prominent corn whiskey is bourbon, which is named for a county in Kentucky where maize grew well in colonial times, and where there was abundant water for both mas.h.i.+ng the grains and cooling the distillate.

Food Words : Aperitif, Digestif : Aperitif, DigestifThese French words describe two functions attributed to concentrated alcohols in the Middle Ages, ideas that live on in both the words and drinking habits. Aperitif Aperitif comes from an Indo-European root meaning "to uncover, to open," and is a drink to be had before a meal in order to open our system to the nourishment to come. comes from an Indo-European root meaning "to uncover, to open," and is a drink to be had before a meal in order to open our system to the nourishment to come. Digestif Digestif comes from an ancient root meaning "to act, to do," and names a drink for the end of the meal that will stimulate our system to a.s.similate the meal's nourishment. Research has found that alcohol does indeed stimulate the secretion of digestive hormones in the stomach. comes from an ancient root meaning "to act, to do," and names a drink for the end of the meal that will stimulate our system to a.s.similate the meal's nourishment. Research has found that alcohol does indeed stimulate the secretion of digestive hormones in the stomach.

Bourbon is made from a mash that's usually 7080% maize, 1015% malted barley to digest the starch, and the remainder rye or wheat. After fermenting for two to four days, the whole mash, grain residues and yeast included, is distilled in a column and then a kind of continuous pot still to 6080% alcohol. The distillate is aged for at least two years in new, charred American oak barrels, which give bourbon a deeper color and stronger vanilla note than Scotch whiskies have. Summer temperatures that can reach 125F/53C in the warehouses modify and accelerate the chemical reactions of aging. Bourbons are generally chill-filtered; in fact this technique was invented by the Tennessee whiskey maker George d.i.c.kel around 1870. Unlike French brandies and Canadian whiskeys, bourbon cannot be colored, sweetened, or flavored; the only additive allowed is water.

Canadian whiskeys are among the mildest and most delicate of the spirits made from grains. They are a blend of a light-flavored column-distilled grain whiskey with small amounts of stronger whiskeys; they can also include wines, rum, and brandy, up to 9% of the blend. They're aged for a minimum of three years in used oak casks.

Gins There are two princ.i.p.al styles of There are two princ.i.p.al styles of distilled distilled gin made today, English and Dutch, as well as cheaper gin that cannot be called distilled because its flavorings are simply added to neutral alcohol. gin made today, English and Dutch, as well as cheaper gin that cannot be called distilled because its flavorings are simply added to neutral alcohol.

The traditional Dutch production method is to distill a fermented mixture of malt, corn, and rye two or three times in pot stills at low proof: that is, the distillate contains a fair amount of congeners, and resembles a light whisky. Then this distillate is distilled one last time, to a minimum of 37.5% alcohol, along with juniper berries and other spices and herbs, whose aromatic molecules end up in the final gin.

English-style, or "dry" gin, begins with neutral 96% alcohol produced from grain or mola.s.ses by other distilleries. This flavorless liquid is then diluted with water and redistilled in a pot with juniper and other flavorings. Juniper is required for the product to be called gin, and most gins also contain coriander. The other ingredients may include citrus peel and a great variety of spices. This distillate is diluted before bottling to 37.5 to 47% alcohol.

The primary aromas in gin come from the terpene aromatics (p. 390) in the spices and herbs, especially notes of pine, citrus, flowers, and wood (pinene, limonene, linalool, myrcene). Dutch gin is generally enjoyed on its own, while beginning in the 1890s, English dry gin inspired many c.o.c.ktails and tall mixed drinks, including the martini, gimlet, and gin and tonic.

Rums Rum got its start in the early 17th century as a by-product of sugar making in the West Indies. Yeasts and other microbes readily grew in the leftover mola.s.ses and wash waters, the yeasts producing alcohol and the bacteria all kinds of aromatic substances, many of them not pleasant. From this mixed material, primitive distillation equipment and methods produced a strong, harsh liquid that was given mainly to slaves and sailors, and traded to Africa for more slaves. Controlled fermentations and improvements in distilling technology brought more drinkable rums in the 18th and 19th centuries. Rum got its start in the early 17th century as a by-product of sugar making in the West Indies. Yeasts and other microbes readily grew in the leftover mola.s.ses and wash waters, the yeasts producing alcohol and the bacteria all kinds of aromatic substances, many of them not pleasant. From this mixed material, primitive distillation equipment and methods produced a strong, harsh liquid that was given mainly to slaves and sailors, and traded to Africa for more slaves. Controlled fermentations and improvements in distilling technology brought more drinkable rums in the 18th and 19th centuries.

There are now two distinct styles of rum. The modern light style is made by fermenting a mola.s.ses solution with a pure yeast culture for 1220 hours, then distilling it to about 95% alcohol in a continuous still, aging it for a few months to eliminate roughness in the flavor, and diluting and bottling it at around 43% alcohol. Some light rums are given a brief time in barrels, but then are pa.s.sed over charcoal to remove the color and some of the flavor.

Traditional Rums Traditional rums are made very differently, and have a much stronger flavor and darker color. Most come from Jamaica and the French-speaking Caribbean (Martinique, Guadeloupe). They were once fermented for up to two weeks with a spontaneous group of microbes, and often by adding the already strong-flavored lees of one fermentation to the next vat. Today, most traditional rums are fermented for a day or two with mixed microbial cultures dominated by an unusual yeast ( Traditional rums are made very differently, and have a much stronger flavor and darker color. Most come from Jamaica and the French-speaking Caribbean (Martinique, Guadeloupe). They were once fermented for up to two weeks with a spontaneous group of microbes, and often by adding the already strong-flavored lees of one fermentation to the next vat. Today, most traditional rums are fermented for a day or two with mixed microbial cultures dominated by an unusual yeast (Schizosaccharomyces) that excels in ester production. They're then pot-distilled to a much lower alcohol content, and therefore end up with four to five times the quant.i.ty of aroma compounds that light rum has. Finally they're aged in used American whiskey casks, where they get most of their color. Caramel can be added to deepen the color and flavor, a procedure that seems appropriate since rum is made from sugar in the first place.

Rums as Ingredients Rums are delicious on their own, but it's their apt.i.tude for other foods that accounts for much of their popularity. Light rums go well with tart-sweet fruits and are the base for a number of tropical c.o.c.ktails, including pina coladas and daiquiris. Medium and dark rums are a useful ingredient in sweets of all kinds thanks to their full caramel flavor. Rums are delicious on their own, but it's their apt.i.tude for other foods that accounts for much of their popularity. Light rums go well with tart-sweet fruits and are the base for a number of tropical c.o.c.ktails, including pina coladas and daiquiris. Medium and dark rums are a useful ingredient in sweets of all kinds thanks to their full caramel flavor.

Vodkas Vodka was first distilled in Russia in medieval times and for medical purposes, and became a popular drink in the 16th century. Its name means "little water." It has traditionally been made from the cheapest source of starch available, usually grain, but sometimes potatoes and sugarbeets. The source is unimportant, since the fermented base is distilled to eliminate most aromatics, and the remainder is removed by filtration through powdered charcoal to produce a smooth, neutral flavor. The essentially pure mixture of alcohol and water is then diluted with water to the desired strength, a minimum of around 38%, and bottled without aging. Vodka was first distilled in Russia in medieval times and for medical purposes, and became a popular drink in the 16th century. Its name means "little water." It has traditionally been made from the cheapest source of starch available, usually grain, but sometimes potatoes and sugarbeets. The source is unimportant, since the fermented base is distilled to eliminate most aromatics, and the remainder is removed by filtration through powdered charcoal to produce a smooth, neutral flavor. The essentially pure mixture of alcohol and water is then diluted with water to the desired strength, a minimum of around 38%, and bottled without aging.

Vodka was scarcely known in the United States until the 1950s, when it was discovered as an ideal alcohol for blending with fruit and other flavors in c.o.c.ktails and tall mixed drinks. Recent years have brought vodkas flavored with citrus and other fruits, with chillis, and with barrel aging.

Grappa, Marc These are the Italian and French names for spirits distilled from These are the Italian and French names for spirits distilled from pomace, pomace, the residue of grape skins and pulp, seeds and stems left behind when wine grapes are pressed. These drinks were born from frugality, as a way of getting the most out of the grapes. The solid remains still have juice, sugar, and flavor in them, so with some water and another period of fermentation, they generate alcohol and flavors that can then be concentrated by distillation, leaving behind the harsh astringency and bitterness. Pomace distillates were very much a by-product, usually distilled just once and often without diverting the heads and tails, and were bottled as is: so they were strong and harsh, something to warm and stimulate the vineyard workers, but not something to savor. In the last few decades, producers have been distilling more selectively and sometimes aging the results to make a fine drink. the residue of grape skins and pulp, seeds and stems left behind when wine grapes are pressed. These drinks were born from frugality, as a way of getting the most out of the grapes. The solid remains still have juice, sugar, and flavor in them, so with some water and another period of fermentation, they generate alcohol and flavors that can then be concentrated by distillation, leaving behind the harsh astringency and bitterness. Pomace distillates were very much a by-product, usually distilled just once and often without diverting the heads and tails, and were bottled as is: so they were strong and harsh, something to warm and stimulate the vineyard workers, but not something to savor. In the last few decades, producers have been distilling more selectively and sometimes aging the results to make a fine drink.

Tequila and Mezcal These spirits are distilled from the carbohydrate-rich heart of certain Mexican species of the agave, a succulent plant in the Amaryllis family that resembles a cactus. Tequila is made mainly by large distilleries around the northerly city of Jalisco from the blue agave, These spirits are distilled from the carbohydrate-rich heart of certain Mexican species of the agave, a succulent plant in the Amaryllis family that resembles a cactus. Tequila is made mainly by large distilleries around the northerly city of Jalisco from the blue agave, Agave tequilana, Agave tequilana, while the more rustic mezcal is made by small producers around central Oaxaca from the maguey, while the more rustic mezcal is made by small producers around central Oaxaca from the maguey, Agave angustifolia. Agave angustifolia.

The agave stores its energy in the sugar fructose and the long fructose chains called inulin (p. 805). Because humans lack an enzyme for digesting inulin, people have learned to cook inulin-rich foods for a long time at a low temperature, a treatment that breaks the chains into their component sugars, and also develops an intense and characteristic browned flavor. Tequila makers steam the inulin-rich agave hearts, which may weight 20100 lb/945 kg, while mezcal producers roast them in large charcoalfired pit ovens and generate smoky aromas that carry over into the spirits. The cooked, sweet hearts are then mashed with water and fermented, and the resulting alcoholicliquid distilled. Tequila distillation is industrial; mezcal is double-distilled, first in small clay pots, then in a larger metal pot still. Most tequila and mezcal is bottled without aging.

Tequila and mezcal have distinctive flavors that include roasty aromas, but also flowery ones (linalool, damascenone, phenylethyl alcohol), and vanilla (vanillin).

Flavored Alcohols: Bitters and Liqueurs Alcohol's split chemical personality, its resemblance to fats as well as water, makes it an excellent solvent for other volatile, aromatic molecules. It does a good job of extracting and holding flavors from solid ingredients. Herbs, spices, nuts, flowers, fruits: all these and more are soaked in alcohol, or distilled along with alcohol, to make a host of flavored liquids. Gin is the best known of these. Most of the others fall into two families: bitters, which are just that, and liqueurs, which are sweetened to varying degrees with sugar. Alcohol's split chemical personality, its resemblance to fats as well as water, makes it an excellent solvent for other volatile, aromatic molecules. It does a good job of extracting and holding flavors from solid ingredients. Herbs, spices, nuts, flowers, fruits: all these and more are soaked in alcohol, or distilled along with alcohol, to make a host of flavored liquids. Gin is the best known of these. Most of the others fall into two families: bitters, which are just that, and liqueurs, which are sweetened to varying degrees with sugar.

Bitters Bitters are modern descendents of medicinal herbal brews that were first made with wine. Purely bitter ingredients include angostura ( Bitters are modern descendents of medicinal herbal brews that were first made with wine. Purely bitter ingredients include angostura (Galipea cusparia), a South American relative of the citrus family, Chinese rhubarb root, and gentian (Gentiana species); plant materials that are both bitter and aromatic include wormwood, chamomile, bitter orange peel, saffron, bitter almond, and myrrh ( species); plant materials that are both bitter and aromatic include wormwood, chamomile, bitter orange peel, saffron, bitter almond, and myrrh (Commifera molmol). Most bitter alcohols are complex mixtures. They may be made by macerating the plant material or by distilling it along with the source of alcohol. Among the bitters commonly used today are Angostura and Peychaud's bitters, condiment-like 19th century formulations that are added to mixed drinks and foods as a flavor accent, and such drinkable aperitifs and digestifs as Campari (unusually sweet) and Fernet Branca.

Some Examples of Flavored AlcoholsFlowers: Sambuca (elderflower), Gul (rose) Sambuca (elderflower), Gul (rose)Spices: Anisette (anise), Pimento (allspice) Anisette (anise), Pimento (allspice)Nuts: Amaretto (almond); Frangelico (hazel); nocino (green walnuts) Amaretto (almond); Frangelico (hazel); nocino (green walnuts)Coffee: Kahlua, Tia Maria Kahlua, Tia MariaChocolate: Creme de cacao Creme de cacaoFruits: Cointreau, Curacao, Grand Marnier, Triple Sec (orange); Midori (melon); Ca.s.sis (black currants); limoncello (lemon); sloe "gin" (plum) Cointreau, Curacao, Grand Marnier, Triple Sec (orange); Midori (melon); Ca.s.sis (black currants); limoncello (lemon); sloe "gin" (plum)Herbs: Benedictine, Chartreuse, Jaegermeister, Creme de menthe, peppermint schnapps Benedictine, Chartreuse, Jaegermeister, Creme de menthe, peppermint schnappsLayering LiqueursThe added sugar that sweetens liqueurs also contributes to their body and density. And because different liqueurs have different proportions of light alcohol and dense sugar, they have densities different enough to allow the mixologist to form distinct layers in the gla.s.s, with the densest liqueurs at the bottom (red grenadine, brown Kahlua) and the lightest at the top (amber Cointreau, green Chartreuse). When the liqueurs have different colors and complementary flavors, this can produce a pleasant novelty drink. Fruit juices and syrups can also play a part in such constructions. Eventually, adjacent liquids will diffuse into each other and the layers disappear.

Liqueurs Liqueurs are a distilled alcohol sweetened with sugar and flavored with herbs, spices, nuts, or fruits. The flavoring agents may be extracted by soaking in the distilled alcohol, or they may themselves be distilled along with the alcohol. Most liqueurs have a neutral grain alcohol as their base, but there are a few whose base is a brandy or whisky. Examples are Grand Marnier, Cognac plus orange peel; Dram-buie, Scotch whisky plus honey plus herbs; and Southern Comfort, bourbon whiskey plus peach brandy and peaches. Some liqueurs include stabilized cream. Liqueurs are a distilled alcohol sweetened with sugar and flavored with herbs, spices, nuts, or fruits. The flavoring agents may be extracted by soaking in the distilled alcohol, or they may themselves be distilled along with the alcohol. Most liqueurs have a neutral grain alcohol as their base, but there are a few whose base is a brandy or whisky. Examples are Grand Marnier, Cognac plus orange peel; Dram-buie, Scotch whisky plus honey plus herbs; and Southern Comfort, bourbon whiskey plus peach brandy and peaches. Some liqueurs include stabilized cream.

Anise and Caraway Alcohols These spirits get their dominant flavor from the seeds of plants in the carrot family, and may be either sweet or dry. Anise is especially popular; there are French, Greek, Turkish, and Lebanese versions among others ( These spirits get their dominant flavor from the seeds of plants in the carrot family, and may be either sweet or dry. Anise is especially popular; there are French, Greek, Turkish, and Lebanese versions among others (pernod and and anisette, ouzo, raki, araq anisette, ouzo, raki, araq). Caraway seeds flavor dry Scandinavian aquavits and the sweet German k.u.mmel. k.u.mmel. When clear anise alcohols are diluted with clear liquid water or ice cubes that melt, the mixture becomes surprisingly cloudy. This is because the aromatic terpene molecules are insoluble in water, and soluble in alcohol only when the alcohol is highly concentrated. As the alcohol becomes diluted, the terpenes separate from the continuous liquid into little water-avoiding droplets, and these scatter light like the fat globules in milk. When clear anise alcohols are diluted with clear liquid water or ice cubes that melt, the mixture becomes surprisingly cloudy. This is because the aromatic terpene molecules are insoluble in water, and soluble in alcohol only when the alcohol is highly concentrated. As the alcohol becomes diluted, the terpenes separate from the continuous liquid into little water-avoiding droplets, and these scatter light like the fat globules in milk.

Vinegar Vinegar is alcohol's fate, the natural sequel to an alcoholic fermentation. Alcohol makes a liquid more resistant to spoilage because most microbes can't tolerate it. But there are a few important and ubiquitous exceptions: bacteria that can use oxygen to metabolize alcohol and extract energy from it. In the process they convert it to acetic acid, which is a far more potent antimicrobial agent than alcohol, and came to be one of the most effective preservatives of ancient and modern times. Alcoholic wine thus becomes pungently acidic wine: in French, vin aigre. vin aigre.

AbsintheThe most notorious herbal alcohol is absinthe, a green-tinged, anise-flavored liqueur whose main ingredient is parts of the wormwood plant, Artemisia absinthium. Artemisia absinthium. Wormwood has a harsh, bitter flavor and carries an aromatic compound, thujone, that in high doses is toxic not only to intestinal parasites and insects - hence the plant's name - but also to the human nervous system, muscles, and kidneys. Absinthe was hugely popular in late 19th-century France, and Wormwood has a harsh, bitter flavor and carries an aromatic compound, thujone, that in high doses is toxic not only to intestinal parasites and insects - hence the plant's name - but also to the human nervous system, muscles, and kidneys. Absinthe was hugely popular in late 19th-century France, and l'heure verte, l'heure verte, "the green hour" of the afternoon when people dripped water through a sugar cube into the absinthe and caused it to cloud up, was depicted by a number of Impressionist painters and by the young Pica.s.so. Absinthe developed a reputation for inducing convulsions and insanity, and was therefore outlawed in many countries around 1910, and replaced by simpler anise-flavored spirits. Whatever toxicity wormwood had for the heavy drinker was probably exacerbated by absinthe's high alcohol content, around 68% and nearly double the strength of most spirits. Absinthe remains legal in a number of countries and has recently enjoyed a modest and moderate revival. "the green hour" of the afternoon when people dripped water through a sugar cube into the absinthe and caused it to cloud up, was depicted by a number of Impressionist painters and by the young Pica.s.so. Absinthe developed a reputation for inducing convulsions and insanity, and was therefore outlawed in many countries around 1910, and replaced by simpler anise-flavored spirits. Whatever toxicity wormwood had for the heavy drinker was probably exacerbated by absinthe's high alcohol content, around 68% and nearly double the strength of most spirits. Absinthe remains legal in a number of countries and has recently enjoyed a modest and moderate revival.

An Ancient Ingredient Because fermented plant juices naturally turn sour with acetic acid, our ancestors discovered wine and vinegar together. In fact, a major challenge in winemaking was to delay this souring by limiting the wine's exposure to the air. The Babylonians were making vinegar from date wine, raisin wine, and beer around 4000 BCE BCE. They flavored their vinegar with herbs and spices, used it to pickle vegetables and meats, and added it to water to make it safe to drink. The Romans mixed vinegar and water to make an ordinary drink called posca, posca, pickled vegetables in vinegar and brine, and judging by the late Roman recipe book of Apicius, often enjoyed vinegar in combination with honey. Pliny said that "no other sauce serves so well to season food or to heighten a flavor." In the Philippines there developed a tradition of serving a variety of uncooked fish, meats, and vegetables in vinegar made from palm sap and tropical fruits. And the Chinese evolved dark, complex vinegars from rice, wheat, and other grains, which are sometimes roasted before fermentation. pickled vegetables in vinegar and brine, and judging by the late Roman recipe book of Apicius, often enjoyed vinegar in combination with honey. Pliny said that "no other sauce serves so well to season food or to heighten a flavor." In the Philippines there developed a tradition of serving a variety of uncooked fish, meats, and vegetables in vinegar made from palm sap and tropical fruits. And the Chinese evolved dark, complex vinegars from rice, wheat, and other grains, which are sometimes roasted before fermentation.

For millennia, vinegar was made simply by allowing partly filled containers of wine and other alcoholic liquids to sour, an unpredictable process that took weeks or months. The first system for more rapid production, a bed of grapevine twigs over which the wine was regularly poured to aerate it, was invented in France in the 17th century. In the 18th a Dutch scientist, Hermann Boerhaave, introduced the continuous trickling of wine over an aerating bed. In the 19th century, Louis Pasteur demonstrated the essential roles of microbes and oxygen in the traditional Orleans process (p. 773). Modern methods for growing baker's yeast and producing penicillin were adapted to vinegar manufacture after World War II, and now produce finished vinegar in a day or two.

The Virtues of Acetic Acid Acetic acid contributes two different flavor elements to foods. One is its acidity on the tongue, and the other is its characteristic aroma in the nose, which can intensify to a kind of startling pungency, particularly when the vinegar is heated. The vinegar molecule can exist in two forms: as the intact molecule, and broken into its main portion and a free hydrogen ion. The hydrogen ion gives the main impression of acidity, while only the intact molecule is volatile and can escape from the vinegar or food, travel through the air, and reach the nose. Both the intact and "dissociated" forms coexist side by side, in proportions that are determined by their chemical surroundings. If the food is already acidic - thanks to the presence of tartaric acid in wine vinegar, for example - then less of the acetic acid dissociates, more is intact and volatile, and the vinegar aroma is stronger.

Acetic acid is an especially effective preserving agent. A solution as weak as 0.1% - the equivalent of a teaspoon of standard-strength vinegar in a cup of water/5 ml in 250 ml - will inhibit the growth of many microbes.

Acetic acid has a higher boiling point than water, 236F/118C. This means that vinegar will get more concentrated if it's boiled. Because half of its molecule is more fat-like than water-like, it is a better solvent than water for many chemical relatives of fats, including the aroma compounds in herbs and spices. This is why cooks flavor vinegars by steeping herbs and spices in them, and why vinegar can help remove greasy films from various surfaces.

Food Words: Vinegar, Acid, Acetic Vinegar, Acid, AceticThough it doesn't look or sound related, the word vinegar vinegar comes from the same root as both comes from the same root as both acid acid and and acetic acetic: the Indo-European ak ak-, meaning "sharp." (The aigre aigre in in vinaigre vinaigre was originally the Latin was originally the Latin acer. acer.)Edge, acute, acrid, ester, and andoxygen are related words, oxygen because its presence was once thought necessary to make an acid. are related words, oxygen because its presence was once thought necessary to make an acid.

The Acetic Fermentation It takes three ingredients to make vinegar: an alcoholic liquid, oxygen, and bacteria of the genus Acetobacter Acetobacter or or Glucon.o.bacter, Glucon.o.bacter, mainly mainly A. pasteuria.n.u.s A. pasteuria.n.u.s and and A. aceti. A. aceti. These bacteria are among the few microbes that are able to use alcohol as an energy source. Their metabolism of alcohol leaves behind two by-products, acetic acid and water. These bacteria are among the few microbes that are able to use alcohol as an energy source. Their metabolism of alcohol leaves behind two by-products, acetic acid and water.

CH3CH2OH + O2[image] CH CH3COOH + H2O Alcohol + oxygen[image] acetic acid + water acetic acid + water Acetic acid bacteria require oxygen, and so live on the surface of the fermenting liquid, where with other microbes they form a film sometimes called the "mother." Especially thick films are created by Acetobacter xylinum, Acetobacter xylinum, which secretes a form of cellulose. (Such mats are sometimes cultivated and eaten for themselves; see p. 509.) Acetobacteria thrive in warm conditions, so vinegar fermentations are often carried out at relatively high temperatures, from 82 to 104F/2840C. which secretes a form of cellulose. (Such mats are sometimes cultivated and eaten for themselves; see p. 509.) Acetobacteria thrive in warm conditions, so vinegar fermentations are often carried out at relatively high temperatures, from 82 to 104F/2840C.

The concentration of alcohol in the starting liquid affects the acetic fermentation and the stability of the resulting vinegar. An alcohol concentration around 5% will produce a vinegar that is around 4% acetic acid, which is strong enough to prevent the vinegar solution itself from spoiling. Above 5% alcohol, the resulting vinegar will be stronger in acetic acid and so more stable, but the fermentation proceeds more slowly because the high alcohol levels inhibit the activity of the bacteria. For this reason, and to minimize residual alcohol in the finished vinegar, wines of 1012% alcohol are usually diluted with water before acetic fermentation. However this also dilutes the wine's flavorful components; so patient vinegar makers may still choose to ferment their wine straight.

Vinegar Production There are three standard ways of producing vinegar in the West.

The Orleans Process The simplest, oldest, and slowest method was perfected in the Middle Ages in the French city of Orleans, where spoiled barrels of Bordeaux and Burgundy wine on their way to Paris were identified and salvaged as vinegar. In the Orleans process, wood barrels are partly filled with diluted wine, inoculated with a mother from a previous batch, and allowed to ferment. Periodically, some vinegar is drawn off and replaced by new wine. This method is slow, because the transformation of alcohol to acetic acid is limited to the wine surface exposed to the air. But the slow fermentation leaves time for reactions among the alcohol, acetic acid, and other molecules, and produces the finest flavor. When optimized, this process can yield a barrel full of vinegar in two months. The simplest, oldest, and slowest method was perfected in the Middle Ages in the French city of Orleans, where spoiled barrels of Bordeaux and Burgundy wine on their way to Paris were identified and salvaged as vinegar. In the Orleans process, wood barrels are partly filled with diluted wine, inoculated with a mother from a previous batch, and allowed to ferment. Periodically, some vinegar is drawn off and replaced by new wine. This method is slow, because the transformation of alcohol to acetic acid is limited to the wine surface exposed to the air. But the slow fermentation leaves time for reactions among the alcohol, acetic acid, and other molecules, and produces the finest flavor. When optimized, this process can yield a barrel full of vinegar in two months.

Streamlined Trickling and Submerged Cultures In the second, "trickling" method, the wine is poured repeatedly over a porous, air-rich matrix - wood shavings, or a synthetic material - onto which the acetic bacteria cling. This greatly increases the effective surface area of the wine, and regularly exposes all parts of the liquid to both oxygen and bacteria. The result is a quick fermentation that takes only a few days. Finally, there is the "submerged culture" method, in which free-swimming bacteria are supplied oxygen in the form of air that is bubbled through the tank. This industrial method converts the liquid's alcohol into acetic acid in 2448 hours. In the second, "trickling" method, the wine is poured repeatedly over a porous, air-rich matrix - wood shavings, or a synthetic material - onto which the acetic bacteria cling. This greatly increases the effective surface area of the wine, and regularly exposes all parts of the liquid to both oxygen and bacteria. The result is a quick fermentation that takes only a few days. Finally, there is the "submerged culture" method, in which free-swimming bacteria are supplied oxygen in the form of air that is bubbled through the tank. This industrial method converts the liquid's alcohol into acetic acid in 2448 hours.

The intact acetic acid molecule, and the acid dissociated into its acetate and hydrogen ions. Only the intact molecule is volatile and detectable in the nose by its distinctive smell. Adding vinegar to an alkaline ingredient - egg whites or baking soda, for example - causes the acetic acid molecules to dissociate, and diminishes its aroma.

After Fermentation After fermentation, nearly all vinegars are pasteurized at 150160F/6570C to kill remaining bacteria of all kinds, but especially the acetobacteria themselves, which respond to the disappearance of the alcohol by metabolizing acetic acid to water and carbon dioxide and thus weakening the vinegar. Most vinegars are aged for a few months, a period in which their flavor becomes less harsh and more mellow, thanks in part to the combination of acetic and other acids with various compounds to form new, less pungent, often aromatic substances. After fermentation, nearly all vinegars are pasteurized at 150160F/6570C to kill remaining bacteria of all kinds, but especially the acetobacteria themselves, which respond to the disappearance of the alcohol by metabolizing acetic acid to water and carbon dioxide and thus weakening the vinegar. Most vinegars are aged for a few months, a period in which their flavor becomes less harsh and more mellow, thanks in part to the combination of acetic and other acids with various compounds to form new, less pungent, often aromatic substances.

Common Kinds of Vinegar Cooks can choose among several different kinds of vinegar. Though all have the basic aroma and pungency of acetic acid, each is distinctive, because they're made with different starting materials, and may or may not be matured in wood.

Wine Vinegars Wine vinegars are made from a base of yeast-fermented grape juice. They therefore have a winey character from the aromatic and savory by-products of the yeast fermentation. Interestingly prominent in wine and cider vinegars are b.u.t.tery aroma compounds (diacetyl, butyric acid). Balsamic and sherry vinegars are specialized versions of wine vinegar (see pp. 775776). Wine vinegars are made from a base of yeast-fermented grape juice. They therefore have a winey character from the aromatic and savory by-products of the yeast fermentation. Interestingly prominent in wine and cider vinegars are b.u.t.tery aroma compounds (diacetyl, butyric acid). Balsamic and sherry vinegars are specialized versions of wine vinegar (see pp. 775776).

Cider Vinegars Cider vinegar is made from a base of yeast-fermented apple juice. It therefore includes some of the characteristic aroma components of apples, and others that are especially accentuated in apple fermentation; these include the volatile phenols that give animal and stable aromas to grape wines (ethyl guaiacol and ethyl phenol, p. 738). Apples are rich in malic acid, so cider vinegars undergo a malolactic fermentation (p. 730) that may augment aroma while softening acidity. Thanks to its pulp and tannin content, cider vinegar often becomes cloudy with tannin-protein complexes. Cider vinegar is made from a base of yeast-fermented apple juice. It therefore includes some of the characteristic aroma components of apples, and others that are especially accentuated in apple fermentation; these include the volatile phenols that give animal and stable aromas to grape wines (ethyl guaiacol and ethyl phenol, p. 738). Apples are rich in malic acid, so cider vinegars undergo a malolactic fermentation (p. 730) that may augment aroma while softening acidity. Thanks to its pulp and tannin content, cider vinegar often becomes cloudy with tannin-protein complexes.

Fruit Vinegars Fruit vinegars may simply be ordinary vinegars flavored by contact with fresh fruit, including apples, but they're also made by fermenting the fresh fruit juices. Pineapple and coconut vinegars are examples. Fruit vinegars are interesting for their expression of the fruit's flavor through the alcoholic and acetic fermentations. Fruit vinegars may simply be ordinary vinegars flavored by contact with fresh fruit, including apples, but they're also made by fermenting the fresh fruit juices. Pineapple and coconut vinegars are examples. Fruit vinegars are interesting for their expression of the fruit's flavor through the alcoholic and acetic fermentations.

Making Vinegars in the KitchenCooks can easily make their own vinegars from leftover wine or from fruits of their own choosing. A few guidelines will improve