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Jack Keller - Wine making glossary Category: Agriculture and Industry Date & country: 28/10/2013, UK Words: 235

Maltase
An enzyme that catalyzes the hydrolysis maltose to glucose.

Malic Acid
A naturally occurring acid found in apples, cherries, grapes grown in less sunny regions, and certain other fruit. It is the presence of malic acid, along with Bacillus gracile, which sometimes produces malo-lactic fermentation.

Malolactic Fermentation
MLF for short, this is a bacterial fermentation which can occur after yeast fermentation winds down or finishes. The bacterium Bacillus gracile converts malic acid into lactic acid and carbon dioxide. Lactic acid is much less harsh than malic and thereby softens and smooths the wine, but the wine also is endowed with a cleaner, fresher taste. In addition, diacetyl (or biacetyl) is produced as a byproduct, which resembles the smell of heated butter and adds complexity to wine. MLF is a positive event in some cases and has a downside in others--the fruitiness of wines undergoing MLF is diminished and sometimes off- odors can result. To ensure MLF, the wine should not be heavily sulfited and it should be inoculated with an MLF culture. If MLF occurs after bottling, it produces a slightly carbonated wine which may or may not be appreciated.

Maceration
The period of time grape juice spends in contact with the skins and seeds.

Mache
French term applied to a big, heavy wine with great lasting properties.

Madre Vino
Spanish for Mother Wine, grape juice or must boiled down to one third or a quarter of its original bulk and used in parts of Spain and France for the improvement and fortification of young fully fortified wines. In Italy it is called calamich.

Liquor
While I don't particularly like this term, associating it as I do with Scotch and other distilled spirits, it does, in fact, also properly refer to the unfermented or incompletely fermented, sugar-bearing liquid from which wine is made. It is also the liquid portion of a must. When the alcohol in the liquor reaches 8 or 9%, it can more accurately be referred to as wine.

Legs
A coating on the inside of the wine glass, after being swirled, that separates into viscous-looking rivulets that slowly slide down the glass to the wine's surface. Legs generally indicate a rich, full-bodied wine.

Lipase
An enzyme that catalyzes the hydrolysis of triglycerides to yield glycerol and fatty acids.

Lactase
An enzyme that catalyzes the hydrolysis of lactose into glucose and galactose.

Lactic Acid
An acid formed in trace amounts during yeast fermentation and in larger quantities during malolactic fermentation, in which bacteria converts malic acid into lactic acid and carbon dioxide. See malolactic fermentation.

Lees
Deposits of yeast and other solids formed during fermentation. This sediment is usually separated from the wine by racking. Sometimes the wine is left in contact with the lees in an attempt to develop more flavor. See Autolysis and Sur Lie Aging.

Jelly-Bag
A bag used to strain the solid fermentation media from the wine. They are similar to grain-bags, but shorter and usually fitted with a drawstring so they can be closed and hung while the liquid drips from the pulp.

Irish Moss
A fining agent made from a red Atlantic seaweed, Chondrus crispus, which is washed, dried and powdered. It is negatively charged and therefore attractive to proteins in suspension. It must be boiled to become active.

Isinglass
A transparent and pure form of gelatin fining agent obtained from the air bladder of certain fish, especially the sturgeon. It is considered by some to be superior to other forms of gelatin, although this is merely an opinion.

Jar
A cylindrical glass or earthenware container with a large mouth and capable of holding liquids, usually without handles.

Invertase
The enzyme yeast use to catalyze the hydrolysis of sucrose to yield an equal mixture of glucose and fructose, yielding invert sugar.

Ice Wine
A rich, flavorful dessert wine made from grapes frozen on the vine and then pressed them before they thaw. Because much of the water in the grapes is frozen, the resulting juice is concentrated, rich in flavor and high in sugar and acid. The resulting wines are extraordinarily sweet, yet balanced by high acidity.

Inoculate
To add an active, selected culture of yeast or malo-lactic bacteria to a must, juice or unfinished wine.

Invert Sugar
The product of the hydrolysis of sucrose, which is glucose and fructose. Yeast convert invert sugar more rapidly than sucrose, such as simple cane sugar, because they do not have to break the sucrose down into glucose and fructose themselves. Invert sugar can be made by dissolving two parts sugar into one part water, adding two teaspoons lemon juice per pound of sugar, bringing this almost to a boil, and holding it there for 30 minutes (NOT allowing it to boil). If not to be used immediately upon cooling, this can be poured into a sealable jar, sealed and cooled in the refrigerator. Invert sugar should NOT be used to sweeten finished wine as it will encourage refermentation.

Hydrolyze
To undergo hydrolysis, or decompose by reacting with water. See Hydrolysis.

Hydrometer Chimney
A tall, narrow, cylindrical vessel used to float a hydrometer in the liquid to be measured. Using this vessel requires a smaller liquid sample than using, for example, a one-gallon open-mouthed jar, as hydrometers tend to be rather long and must be floated in a deep vessel.

Hot Wine
A wine with excessive alcohol that creates a burning, prickly sensation in the mouth and throat.

Hydrolysis
The decomposition of a chemical compound by reaction with water, such as the dissociation of a dissolved salt or the catalytic conversion of starch to glucose. Also, the breaking down of a chemical compound into two or more simpler compounds by reacting with water. The proteins, pectins, and complex carbohydrates in wine are broken down by hydrolysis that is catalyzed by enzymes added to the must or created by the yeast.

Hazy
A relatively clear wine that has a moderate amount of suspended particulates. Not quite as severe a fault as cloudiness.

Heat Stabilization
The process of removing excess protein to preserve a wine's clarity when stored under warm conditions. Heat stabilization is usually performed with a Bentonite fining.

Herbaceous
An odor suggestive of herbs or broken green stems of plants. It is a positive characteristic is suggestive of the base and not too pronounced, but a fault if excessive or from spoilage.

Grain-Bag
A long bag of finely woven net-like material (mesh) used for suspending grain or other fermentation media in liquid during fermentation to ease the removal of the solids later. Grain-bags come in various mesh and sizes and can be used in lieu of a jelly-bag for straining the solid fermentation media from the wine.

Gross Lees
Loose sediments containing a large quantity of fine pulp from the fruit or other base materials from which the wine is made. The pulp does not compact well on its own and therefore is loosely suspended in wine. Gross lees can be compacted somewhat by adding gelatin to the wine, or they can be coarsely filtered or centrifuged to recover much of the wine trapped within them.

Glycerol
A colorless, odorless, slightly sweet, syrupy substance produced naturally during fermentation that gives the palate an impression of smoothness in a wine. Also known as glycerin.

Gassy
A wine with carbonation, usually produced by a secondary fermentation in the bottle, but also unexpectedly and unintentionally produced by malo-lactic (bacterial) or alcohol (yeast) fermentation.

Geranium
A fault caused by sorbic acid degeneration, characterized by the odor of geraniums. The offending compound is 2-ethoxy-hexa-3,5-diene.

Glucose
One of two simple fermentable sugars in grapes and other fruit, the other being fructose. Glucose is approximately half as sweet as fructose.

Frizzante
Italian term for a mildly carbonated wine causing a slight sensation on the tongue, but enough carbonation to produce bubbles in the glass the way Champagne or other sparkling wines do. P

Fructose
One of two simple (reducing) fermentable sugars in grapes and other fruit, the other being glucose . Isolated, fructose is approximately twice as sweet as glucose. In wine, a higher fructose concentration will result in a heightened sweetness threshold.

Free SO2
Sulfur dioxide ions in solution in must, juice or wine that are not chemically bound to other chemicals in solution and thus are free to react with such substances as acetalhyde or oxygen or to escape the must, juice or wine as a gas molecule.

Fortification
The process of adding distilled spirits to a finished wine to increase its alcohol content, improve its preservation qualities, or improve its flavor. Brandy is often used as a fortifying agent because it is made from wine, but vodka, gin, Everclear, or any distilled spirit may be used. Each fortifying agent has its own flavor and will impart this to the fortified wine.

Flat
A taste denoting a wine with insufficient total acidity. The taste is truly flat, lifeless, medicinal, and wholly wrong. Technically, it is the absence of the sour taste. This taste appears in wines with a pH greater than 3.75 and a titratable acidity less than 0.5%. The opposite (the taste of excessive total acidity) is Acidulous.

Flocculation
The term has one meaning for brewers and another for winemakers. For brewers, it refers to the process of yeast clumping together and falling to the bottom when fermentation is complete. A yeast known to possess high flocculation tendencies will have a very high percentage of yeast cells that clump together and fall to the bottom, thereby leaving the beer very clear. Low flocculation strains leave a beer cloudy. In winemaking, the term refers to the process of settling or compacting of lees or sediment. Lightly or loosely flocculated lees are less dense than tightly or compactly flocculated ones and contain more wine in them. Good flocculation refers to greater density and less wine lost when racking. The term has lost favor in winemaking in recent decades.

Fixed Acids
Those acids occurring naturally in the grape or fruit base, those added by the vintner, and those acids created during fermentation which are stable -- fixed. In grapes and grape wine, the major fixed acid is tartaric, followed by malic, then citric, succinic, and lactic, although the latter three are not necessarily listed in the order of their prominence in the finished wine as they can vary greatly. Succinic, for example, is usually more naturally prominent in grape wines than citric.

Finish
The final flavor, texture and impression that remains on the palate after a wine is swallowed.

Fining
Removing suspended solids from a cloudy wine by temperature adjustment, blending with an already cleared wine of the same variety, filtering, or adding a fining material such as egg white, milk, gelatin, casein, or bentonite.

Field Blend
The practice of planting a vineyard with several grape varieties which are harvested together and all contribute to a common wine. Similarly, the mixing of grapes before the crush to constitute a field blend must.

Filtering
The process of removing yeast cells and other microorganisms that could spoil the wine, as well as any remaining sediment that would keep it from being crystal clear, by pumping the wine through cellulose pads, pads lined with diatomaceous earth, or especially fine membranes.

Fermentation Trap
A glass or plastic device designed to use water as an insulator to protect the fermentation media from contamination and exposure to fresh air, while at the same time allowing carbon dioxide produced by the yeast to escape the fermentation vessel. Also called an air lock, bubbler or airlock.

Fermentation Media
The pulp or other solid material from which wine will be made. Fermentation media differs from must in that the must is the media, the water, the yeast, and all other ingredients mixed together, while the fermentation media more narrowly refers to the crushed grapes, chopped raisins, pulped peaches, cracked wheat, or other material used either for flavoring, natural sugar content, or both. It is also called the base ingredient or wine base.

Fermentation Bottle
Sometimes called the secondary fermentation vessel, a fermentation bottle is a shouldered, small-mouthed glass jug or carboy in which the liquor or juice is placed to complete fermentation under a fermentation trap.

Fermentation
The process of yeast acting upon sugar to produce alcohol and carbon dioxide.

Faded
Descriptor for a wine that has suffered insipient oxidation -- i.e. has passed its prime and is declining in quality.

Essential Oils
Volatile oils that impart distinctive odors or flavors which, in wine, combine with alcohol and contribute to its bouquet.

Esters
Volatile, aromatic, organic compounds formed by the chemical interaction of the wine's alcohol, acids and other components during maturation.

Ethanol
An alcohol, C2H5OH, produced by distillation or as the principal alcohol in an alcohol fermentation by yeast. Also know as Ethyl Alcohol.

Ethyl Acetate
An ester produced by fermentation. When ethyl acetate exists in sufficient quantity, it produces a slightly sweet, fruity, vinegary smell. Too much is considered a flaw.

Effervescence
An excess of dissolved carbon dioxide in a wine. The French have a more precise terminology for degrees of effervescence than does English

Enology
The science and study of winemaking, also spelled oenology.

Enzyme
Any of numerous protein molecules produced by living organisms (including yeast) and functioning as catalysts in biochemical reactions. Despite their derivation from living materials, are not living organisms themselves. Enzymes emerge intact from the catalytic reactions they produce and are denatured (rendered inactive) by pH extremes and high temperatures. Usually, an enzyme acts only on a specific molecule (substrate), so an enzyme that acts upon pectin will not act upon starch. In winemaking, most of the essential enzymes are produced by yeast, but some are not and must be introduced by the winemaker. Some of the more important enzymes that find use in winemaking are

Earthy
The unpleasant odor of damp soil that is perceived in the mouth. Most wines made from roots (beet, carrot, parsnip, rutabagas, turnip) possess an earthy quality that diminishes to neutral over time -- usually two years, but possibly more -- and should not be served until neutralized by age. Whenever perceived, it is a fault.

Dinner Wine
A still wine, usually light to medium in body, dry to semi-dry, low to moderate in alcohol (10% to 13% by volume), and often served with meals. Also called table wine.

Disgorgement
The process of removing the sediment from the bottle during the m

Dosage
A syrupy mixture of sugar and wine that's added to still wine, along with yeast, to fuel a secondary fermentation in the bottle to make champagne and other sparkling wine.

Dry
A wine lacking or deficient in residual sugar. A wine becomes dry when all or most of the sugar within it has been converted through fermentation into alcohol and carbon dioxide. A wine is usually perceived as dry when residual sugar is at or below a specific gravity of 0.999.

Dessert Wine
A still wine type that is both sweet and high in alcohol and usually served after a meal or with a dessert. Dessert wines typically have 17% to 22% abv. Port and Sherry are the two best known dessert wines, but others include Madeira, Malaga, Marsala, Muscatel, and Tokay.

Diammonium Phosphate
One of the major ingredients in almost all yeast nutrients and energizers, serving as their basic source of nitrogen. Also known as DAP.

Demijohn
A large-bodied, small-mouthed, long-necked wine bottle, usually covered with wicker, used to store wine or as a secondary fermentation vessel. Demijohns come in many sizes, including 5-, 10-, 15-, 20-, and 25-gallon (Imperial).

Demerara Sugar
A light brown sugar with large golden crystals which are slightly sticky. While this sugar is often expensive, it has a unique, unmatched flavor.

Degasse
The process of removing dissolved carbon dioxide from a wine to bring it to stillness. Vigorous stirring and applying a vacuum are the two most common ways of achieving this.

Deacidification
The process of reducing the amount of titratable acid in must, juice or wine. This is usually done by chemical neutralization, cold stabilization and/or amelioration.

Crust
The sediment thrown off by red wines as they age in bottles--usually associated with sediments in port.

Crock
A large-mouthed, cylindrical, earthenware vessel, glazed to contain liquid. The best sizes for winemaking are 1-1/2 gallon, 3 gallons, and 6 gallons; these adequately handle the ingredients for any 1 gallon-, 2 gallon-, or 5 gallon-batch recipe.

Corkscrew
Device for removing corks from wine bottles. See Wine Openers at Wine Accessories.

Corked Wine
A wine that's been affected by a faulty cork, specifically by a chemical compound (2,4,6-Tricloroanisole- 246-TCA) that humans can perceive at levels as low as 30 parts per trillion. High levels of this compound produce an unmistakably odor and flavor that many describe as that of moldy, wet cardboard or newspapers. At moderate levels, a corked wine takes on a musty quality; at lower levels, it seems lacking in fruit.

Cold Stabilization
The process of removing excess potassium and tartaric acid under chilled conditions as Potassium Bitartrate to prevent its precipitation in the bottle when chilled.

Complexity
Multiple layers and nuances of bouquet and flavor that are perfectly balanced, completely harmonious, and delightfully interesting.

Cork
Wine bottle closure made from the bark of cork oaks (Quercus Suber). Quality corks have very fine grain, only minor or no faults, good compressibility, and have been cured to contain between 5 and 8% moisture.

Cloudiness
A wine that is visually unclear. Cloudiness is considered a severe fault often due to faulty winemaking.

Claret
Properly, the English term for the red wines of Bordeaux, but more commonly the term for any light red wine.

Clarify
The process of a wine becoming clear, which occurs when all of the yeast and microscopic bits of pulp from the base ingredients of the wine settle to the bottom of the secondary, leaving a clear wine without haze. A wine that has clarified to the nth degree and is crystal clear is called brilliant.

Citric Acid
A colorless acid found in all citrus fruit, pineapples, and in lesser amounts in several other fruit.

Carboy
A large glass or plastic bottle of 2-gallon capacity or more, with or without handles, and sometimes fitted with a spigot or plastic tubing at the bottom for drainage. Carboys are usually 3-, 5- or 6-gallons, but the author has seen all of the following 2-gallon, 2.2-gallon, 2.5-gallon, 2.8-gallon, 3-gallon, 5- gallon, 6-gallon, 6.5-gallon, and 7-gallon.

Casein
A fining agent made from milk protein.

Chaptalize
To add sugar to a must or juice to increase its alcohol potential, or to a new wine to balance the taste of its alcohol or the bite of its acidity or tannin. The word is a methode named after M. Chaptal, who in 1801 accurately calculated the amount of sugar to add to a wine to achieve balance.

Carbonic Maceration
A technique for producing light red wines with low tannins, intense color, and fresh, fruity flavors and aromas. This process involves dumping whole bunches of freshly picked, uncrushed grapes into large vats filled with carbon dioxide. The bottom grapes are crushed by the weight of the grapes above them, and fermentation begins with the exuded juice and develops upward. Eventually, fermentation begins within the whole grapes, and they begin to exude more juice. Finally, the whole batch is pressed, and fermentation is finished in a standard way.

Carbon Dioxide
The colorless, odorless gas emitted by yeast during fermentation. During Aerobic Fermentation, the gas fills the Ullage but does not completely prevent desired oxygen from entering the Must. During Anaerobic Fermentation, the gas fills the Ullage but the Air Lock prevents undesired oxygen from entering the must. An Air Lock allows carbon dioxide to escape without allowing oxygen into the fermentation vessel. The chemical shorthand for carbon dioxide is CO2.

Caramelized
The taste and/or odor of caramel, achieved by heating a sweet wine. In non-grape wines, this characteristic can be achieved by cooking the fruit to extract the juice, set the color or extract polyphenolic compounds from the skins. It is the browning of sugar that most often produces this character. Juice that is steam extracted usually does not possess this characteristic. The perception of some caramel is desired in some wines (sweet sherries), but considered a fault in most others.

Capsule
A decorative foil, plastic, or mylar sleeve placed over the cork and neck of a wine bottle.

Calamich
Italian term for grape juice or must boiled down to one third or a quarter of its original bulk and used for the improvement and fortification of young fully fortified wines. In Spain it is called Madre Vino.

Campden Tablets
Tablets used in winemaking to sanitize equipment and fermentation media and add free SO2 to the must or wine. When crushed and dissolved, they provide sulfur dioxide (SO 2) in a convenient form. Tablets must be crushed to use, but this ensures the proper dosage and assists in their dissolution. The active ingredient in Campden tablets can be purchased bulk from most winemaker suppliers under its chemical name, potassium metabisulfite. For sanitizing bottles, primaries, secondaries, funnels and other equipment, two crushed tablets dissolved in 1 gallon of water will suffice. Do not rinse equipment after sanitizing. For adding to must, use one crushed and dissolved tablet per gallon of must and wait 12 hours before adding yeast. Campden tablets come in various sizes and doses and may contain either sodium metabisulfite or potassium metabisulfite, so inquire if not packaged with instructions. Campden tablets were developed by the Fruit and Vegetable Preserving Research Station at Campden, Glos., England, as a durable replacement for the Campden Fruit Preserving Solution. The latter was developed circa 1920-1923. Also see Potassium Metabisulfite and Sodium Metabisulfite.

Bung
In cooperage, a wooden stopper used to seal the cask, keg or barrel. In glassware, usually a rubber stopper used to seal a demijohn, carboy or jug. Bungs may be either solid or drilled with a central hole to accept a fermentation lock (airlock). Some bungs have two holes drilled to accept two airlocks, or one airlock and a blow-off tube.

Bulk Aging
The aging of wines in vats, barrels, casks, demijohns, carboys, or gallon jugs prior to bottling. An advantage of bulk aging is that the wine ages evenly and sediments developed during aging can be left behind when the wine is bottled.

Bubbler
A glass or plastic device designed to use water as an insulator to protect the fermentation media from contamination and exposure to fresh air, while at the same time allowing carbon dioxide produced by the yeast to escape the fermentation vessel. Also called an air lock, fermentation trap or airlock.

Brown Sugar
Sugar crystals coated in a molasses syrup with natural flavor and color. Many sugar refiners produce brown sugar by boiling a special molasses syrup until brown sugar crystals form. A centrifuge spins the crystals dry. Some of the syrup remains, giving the sugar its brown color and molasses flavor. Other manufacturers produce brown sugar by blending a special molasses syrup with white sugar crystals. Dark brown sugar has more color and a stronger molasses flavor than light brown sugar. Lighter brown sugars are more commonly used in winemaking than darker ones, as the richer molasses flavors in the darker sugar tend to mask the bases flavors of the wine, but both have their place.

Brilliant
A descriptor denoting absolute, crystalline clarity in a wine.

Brix
One of several hydrometer or saccharometer scales denoting the density of liquid (must, juice or new wine) in terms of specific gravity. Each degree Brix is equivalent to 1 gram of sugar per 100 grams of liquid. The potential alcohol of a must is estimated by multiplying the Brix reading by 0.55. Both the Brix and Balling scales are comparable and are usually used to finely estimate sugar content.

Bottling Wand
A stiff plastic tube with a one-way flow valve at the lower end that is used in Bottling. In its simplest form, when the tip is pressed against the bottom of a bottle, wine flows into the bottle. When the tip is lifted, the flow-valve closes and stops the flow of wine.

Bouquet
The complex, vaporous scent(s) released when a cask or bottle is opened, derived from volatile esters, ethers and acids formed during aging. Bouquet may rapidly dissipate or be slowly released, but when gone the wine is left with aroma, the fragrance of the fruit the wine was made from.

Bottle Bouquet
A wine's bouquet, captured in the bottle the wine is aged and distributed in. See Bouquet.

Bottle Sickness
A period following bottling during which the wine is flat, uninspiring and possibly unpalatable. This is a temporary condition which usually lasts no longer than a month and rarely two.

Bottling
The process of transferring wine from a Secondary into wine bottles with a Racking Hose. The process can be assisted with the use of a Bottling Wand. Usually, Bottling includes corking, affixing capsules, and labeling the bottles.

Bottle Aging
The aging of wine in the bottles it will be distributed in rather than in vats, barrels, casks, demijohns, carboys, or gallon jugs. Bottle aging preserves the bouquet, which can be lost when the wine is bulk aged and then transferred to bottles. However, a bulk-aged wine can be bottled and subsequently develop a bottle bouquet.

Bottle
The most common wine bottle size worldwide is 750 ml, but it is not standard. Some German wine bottles are a liter, some are 700 ml, while some from Alsace are 720 ml. Every wine bottle consists of a mouth, neck, ogive or shoulder, body, and bottom. The bottom may contain an indention, the term for which is a punt. Some almost standard names for different size wine bottles are