Winemaking Glossary Of Terms

winemaking instructions and wine making recipes in Guelph

KJ Urban Winery in Guelph provides exceptional products and instructions to help you create your own unique wine from home as well as through our cooperative winemaking program. Below is a list of terms that apply specifically to winemaking and will help guide you along the production and fermentation processes.

Contact us for additional information or to register for our cooperative winemaking program in Guelph.

Terms From A-Z

Acetic acid

One of the primary volatile acids in wine. Also called Ethanoic acid.


A bacterium found in wine that causes acetification resulting in the conversion of wine to vinegar.


The quality of wine that gives it its crispiness and vitality. A proper balance of acidity must be struck with the other elements of a wine, or else the wine may be said to be too sharp – having disproportionately high levels of acidity – or too flat – having disproportionately low levels of acidity. The three main acids found in wine are tartaric acid, malic acid and lactic acid. The first two come from the grapes and the third from Malolactic fermentation which often occurs in the winemaking process.

Aerobic conditions

Winemaking conditions that promote exposure to oxygen, such wine barrels kept partially full in order to oxidatively age the wine

Aging barrel

A barrel, often made of oak, used to age wine or other beverage Alcohols.


The “fermentation lock” or “airlock” is a device used in beer brewing and wine making that allows carbon dioxide released during fermentation to escape the fermenter, while not allowing air to enter the fermenter, thus avoiding oxidation.

Alcoholic fermentation

The conversion by yeast of sugar into alcohol compounds


A component of wine that is formed during the oxidation of alcohol. It is midway between an acid and an alcohol.


The opposite of aerobic, referring to a chemical process that takes place in the absence of oxygen. As a wine ages in a sealed wine bottle, it is going through anaerobic changes.

Angel’s share

The portion of a wine in an aging barrel that is lost to evaporation.


Chemicals, such as sulfur dioxide or ascorbic acid, that are used to prevent the grape must from oxidizing.


The measure of atmospheric pressure within a wine bottle. The average internal pressure inside a bottle of sparkling wine is 6 atmospheres.


The breakdown of dead yeast cells (or lees) and the process through which desirable or undesirable traits may be imparted to the wine. Wines that are deliberately aged sur lie such as Muscadet or some white Burgundies derive certain flavors and textures from this process.


Blending unfermented, fresh grape juice into a fully fermented wine in order to add sweetness.

Barrel fermented

A wine fermented in oak barrels as opposed to stainless steel or concrete. Traditional with white Burgundies, some Chardonnays and some Champagne.


A type of clay of volcanic origins used in wine as a clarifying agent. We’ve found that nothing works quite as well as bentonite at clarification.


The mixing of two or more different parcels of wine together by winemakers to produce a consistent finished wine that is ready for bottling. Laws generally dictate what wines can be blended together, and what is subsequently printed on the wine label.

Bottle shock

Also known as bottle-sickness, a temporary condition of wine characterized by muted or disjointed fruit flavors. It often occurs immediately after bottling or when wines (usually fragile wines) are shaken in travel. After several days the condition usually disappears.

Bottle Tree

A plastic or metal structure designed to drain recently rinsed bottles so they may dry properly.


A wine spoilage yeast that produces taints in wine commonly described as barnyard or band-aids.


A measurement of the dissolved sucrose level in a wine


A French term for a very dry Champagne or sparkling wine. Drier than extra dry.


A stopper used to seal a bottle or barrel. Commonly used term for corks.


The layer of grape skins that are forced by rising carbon dioxide gas to the top of the fermentation vessel during cuvaison.

Carbonic gas

A natural byproduct of the fermentation process in which yeast cells convert sugar into nearly equal parts alcohol and carbonic gas. While a small amount stays presence in the wine as carbonic acid, most of the gas will rise to the surface of the fermentation vessel and attempt to escape into the air. If the fermentation vessel is closed (such as a sealed wine bottle used to make sparkling wine), the gas will dissolve into the wine and when released will make the wine sparkling.


A glass or plastic vessel usually 18.9L (5 USgal), 19.6L (5.2 USgal) or 23L (6 gal) in size with a variety of uses for wine and beer making.


A wood barrel or storage vessel, often made from oak, that is used in winemaking for fermentation and/or aging

Charmat method

Sparkling wine production method where the secondary fermentation takes place in a tank as opposed to the traditional method where it takes place in the individual wine bottle that the consumer eventually purchases


A winemaking process where sugar is added to the must to increase the alcohol content in the fermented wine. This is often done when grapes have not ripened adequately.


A winemaking process involving the fining and filtration of wine to remove suspended solids and reduce turbidity.

Cold stabilization

A winemaking process where wine is chilled to near freezing temperatures for several weeks to encourage the precipitation of tartrate crystals. At KJ, our wines undergo a minimum of 3 weeks of cold stabilization.


Wine conditioner, or wine sweetener is used at, or slightly before bottling to soften the wine’s acidity and astringent characters.  Primarily derived from Fructose of Cane Sugar.  Can also sweeten wine, but is typically not recommended for that purpose. We offer complimentary conditioner at bottling here at KJ.

Cork taint

A type of wine fault describing undesirable aromas and flavors in wine often attributed to mold growth on chlorine bleached corks.


A beer bottle cap used as a temporary closure for a sparkling wine as it undergoes as secondary fermentation.


After harvest, and prior to pressing, grape are “crushed” or broken up so that the juice is released and allowed to macerate with the skins prior to and during fermentation. In viticultural terms, “Crush” is used as a synonym for harvest time.


A blending term used to refer to either blending a wine with one distinct characteristic (such as high acidity) into a wine that currently dominated by the opposite characteristic (such as low acidity). It can also mean blending a red wine with a white wine in order to make a rosé.


The disgorging or removal of sediment from bottles that results from secondary fermentation.


A glass vessel usually found in a basket of some sort ranging in sizes from 3.8L (1 gal) to 54 L (15 gal).  Demijohns have a variety of uses in wine and beer making.

Dosage (wine)
The addition of sugar with the liqueur d’expedition after degorgement where the sweetness level of a sparkling wine is determined


Wines with zero or very low levels of residual sugar. The opposite of sweet, except in sparkling wines, where dry means sweet.


Compounds formed in wine either during fermentation or the wine’s aging development that contribute to a wine’s aroma.


Also known as “ethyl alcohol”. The primary alcohol in wine and most other alcoholic beverages. The alcohol content of a wine contributes to its body.

Extra dry

A champagne or sparkling wine with a small amount of residual sugar (slightly sweet). Not as dry as Brut.


An unpleasant characteristic of wine resulting from a flaw with the winemaking process or storage conditions.


A chemical reaction in winemaking. In alcoholic fermentation it is the conversion of sugars to alcohol by yeast while in malolactic conversion it is the conversion of malic acid to lactic by bacteria.

Filling Tube

A tube used at the end of a siphon hose to help fill bottles


A clarification process where flocculants, such as bentonite or egg white, are added to the wine to remove suspended solids. Fining is considered a more gentle method of clarifying a wine than filtering.

First pressing

The first press, after the free run juice has been collected, that contains the clearest and cleanest juice that will come out of pressing.

Fixed sulfur

The molecules of sulfur dioxide that binds with sugar and acids in the wine. This leaves the unbound “free sulfur” to combine with molecules of oxygen in order to prevent oxidation.

Flash Pasteurization

A procedure different from full pasteurization where the wine is subjected to high temperatures around 72°C for intervals of 30-60 seconds. KJ uses a modified flash pasteurization regimen to package our fresh juices.


The process of adding pure alcohol or very strong grape spirit to a wine. Depending on when the alcohol is added, either before, during or after fermentation, this can result in a wine with a high alcohol content and noticeable sweetness.

Fruit wine

A fermented alcoholic beverage made from non-grape fruit juice which may or may not include the addition of sugar or honey. Fruit wines are always called “something” wines (e.g., plum wine), since the word wine alone is often legally defined as a beverage made only from grapes. Most wineries outside of the Niagara, and Prince Edward County region are fruit wineries.

Fully fermented

A wine that was allowed to complete the process of fermentation without interruption to produce a wine that is completely dry.


A fining agent used to remove excessive amounts of tannins and other negatively charged phenolic compounds from the wine.

Hydrogen sulfide

The combination of hydrogen and sulfur dioxide which can produce a fault in the wine reminiscent of the smell of rotting eggs that may eventually develop in the bottle into mercaptans.


Measures the specific gravity of liquids. This device is used to identify the amount of fermentable sugar in a must, and is also used to see if the sugar has been completely consumed by the yeast resulting in a fully fermented wine. These are one of the most important instruments in winemaking.


A clarifying agent which is a form of collagen derived from fish.


Also know as a “racking cane”, a J-Tube attached to a hose, is used to help siphon or pump wine from a vessel without collecting the sediment at the bottom.


Colloidal Silica is used as a fining agent with other oppositely charged fining agents to help settle particulates into sediment.  

Lactic acid

The acid in wine formed during the process of malolactic fermentation.


Wine sediment that occurs during and after fermentation, and consists of dead yeast, grape seeds, and other solids. Wine is separated from the lees by racking.

Lees stirring

Also known as bâttonage, A process associated with sur lie aging where the lees are stirred up to extract flavor and other sensory components into the wine and to avoid reductive conditions that may contribute to various wine faults


The contact of grape skins with the must during fermentation, extracting phenolic compounds including tannins, anthocyanins, and aroma.


A wine showing Madeira-like flavor, generally evidence of oxidation. Sometimes used to describe white wine that has been kept long past its prime.

Malic acid

A strong tasting acid in wine reminiscent of the flavor of green apples. The amount of malic acid in grapes is gradually reduced during the ripening process while the grapes are on the vine and can be further reduced during winemaking by fermentation and malolactic fermentation.

Malolactic fermentation

Also known as malo or MLF, a secondary fermentation in wines by lactic acid bacteria during which tart tasting malic acid is converted to softer tasting lactic acid, during which carbon dioxide is generated.


The controlled exposure of wine to small amounts of oxygen in the attempt to reduce the length of time required for maturation.


A winemaking technique often used for experimental batches of wine where the wine is fermented in small, specialized vats.


A winemaking abbreviation for “Material Other than Grapes”. Usually refers to debris like leaves, dirt and stems that can be unintentionally harvested with the grapes.[3]


Unfermented grape juice, including pips (seeds), skins and stalks.


The most commonly used wood source for fermentation vessel and barrel aging. Oak influence can also be imparted to a wine by the use of oak chips, barrels or staves.


The science of wine and winemaking.


A wine that has the barest hint of sweetness; a slightly sweet wine in which the residual sugar is barely perceptible.

Orange wine

A white wine with extending skin contact, similar to red wine production. The opposite of a rosé


The degradation of wine through exposure to oxygen. In some aspects oxygen plays a vital role in fermentation and through the aging process of wine. But excessive amounts of oxygen can produce wine faults.

Pad Filtration

A technique of filtering wine that involves running the wine through a series of pads made of asbestos, cellulose or thin paper sheet.


An umbrella term for various methods of sterilization and stabilization of the grape must.

Pectic enzyme

An enzyme added to fruit to increase juice yield. Also used as a clarifying agent in fruit wines when added to wine or must to eliminate pectin hazes.


A measure of the acidity. The lower the pH, the higher the acidity.

Phenolic compounds

Compounds found in the seeds, skins and stalks of grapes that contribute vital characteristics to the color, texture and flavor of wine.


An ultrafine means of filtration that leaves a wine with exceptionally bright clarity – giving the impression that it has been polished. Premium wines will often decline polishing because ultra fine precision can also remove flavor and phenolic compounds that may diminish the quality and aging potential of the wine.

Potassium Metabisulfite

Potassium metabisulfite is a common wine or must additive, in which it forms sulfur dioxide gas (SO2). This both prevents most wild microorganisms from growing, and it acts as a potent antioxidant, protecting both the color and delicate flavors of wine.

Potassium sorbate

A wine stabilizer and preservative. It does not allow yeast and mold to reproduce.  Works best with Potassium Metabisulphite.

Potential alcohol

The calculation, based on brix, must weight and other measurements, of the potential finished alcohol levels if a batch of grape must was fermented to complete dryness

Pre-fermentation maceration

The time prior to fermentation that the grape must spends in contact with it skins. This technique may enhance some of the varietal characteristics of the wine and leech important phenolic compounds out from the skin.

Protein haze

A condition in wines with an excessive amount of protein particles. These particles react with tannins to create a cloudy, hazy appearance in the wine. This condition can be fixed with the use of a fining agent, such as bentonite, to remove the proteins.


A group of aromatic compounds in grapes that contribute to some of the green herbaceous notes in wine from the green bell pepper notes in some Cabernet Sauvignon to the grassy notes of some Sauvignon blanc.


The process of drawing wine off the sediment, such as lees, after fermentation and moving it into another vessel. At KJ we do this once primary fermentation has finished. Typically this is 10-14 days after inoculation. Racking is critical to improving clarity, and can be done many times throughout production.


French term for the process of pulling out wine from underneath the cap of grape skins and then pumping it back over the cap in order to stimulate maceration.

Residual sugar

The unfermented sugar left over in the wine after fermentation. All wines, including those labeled as “dry wines” contain some residual sugars due to the presence of unfermentable sugars in the grape must such as pentoses.


Also known as “Rémuage” in French, part of the Méthode Champenoise process whereby bottles of sparkling wine are successively turned and gradually tilted upside down so that sediment settles into the necks of the bottles in preparation for degorgement.


An Italian method of winemaking that involves putting a wine through a secondary fermentation on the lees from a previously made recioto wine. This method is common in the Valpolicella area among Amarone producers who make a secondary Ripasso wine.

Rosé wines

Pink wines are produced by shortening the contact period of red wine juice with its skins, resulting in a light red colour. These wines are also made by blending a small amount of red wine with white wine.


Pronounced “sahn yay” is the removal of grape juice from the “must” before primary fermentation to increase a wines skin/juice ratio. Typically done after 24 hrs of cold soak and prior to inoculation.


An alternative to cork for sealing wine bottles, comprising a metal cap that screws onto threads on the neck of a bottle. Screwcap bottled wine do not age as well as natural corked wine bottles. Typically, a wine with a screwcap is meant to be consumed shortly after purchase.


French for dry, except in the case of Champagne, where it means semi-sweet.

Secondary fermentation

Most commonly the term is used to refer to the continuation of fermentation in a second vessel – e.g. moving the wine from a stainless steel tank to an oak barrel. The Australian meaning of this term is malo-lactic fermentation MLF, as distinct from primary fermentation, the conversion of sugar to alcohol.


A process of adding carbonic gas to a wine just before bottling in order to add some slight effervescence to the wine.


The process of decreasing the volatility of a wine by removing particles that may cause unwanted chemical changes after the wine has been bottled. In winemaking wines are stabilized by fining, filtration, adding sulfur dioxide or techniques such as cold stabilization where tartrate chemicals are precipitated out.


Cutting or diluting a wine with water, often used to lower the alcohol level of the wine. In many wine regions this practice is illegal.

Stuck fermentation

A fermentation that has been halted due to yeast prematurely becoming dormant or dying. There are a variety of causes for a stuck fermentation including high fermentation temperatures, yeast nutrient deficiency, or an excessively high sugar content.

Sur lie

A winemaking practice that involves prolonged aging on the dead yeast cells (the lees).


A reserve of unfermented grape juice that is added to wines as a sweetening device.

Sweetness of wine

Defined by the level of residual sugar in the final liquid after the fermentation has ceased. However, how sweet the wine will actually taste is also controlled by factors such as the acidity and alcohol levels, the amount of tannin present, and whether the wine is sparkling.

Tank method

Also known as the “Charmat” or “Cuve close” method where the secondary fermentation of sparkling wine production takes place under pressure within a sealed tank.


Phenolic compound that give wine a bitter, dry, or puckery feeling in the mouth while also acting as a preservative/anti-oxidant and giving wine its structure. It is derived from the seeds (pips), skins and stalks of grapes.

Tartaric acid

The primary acid found in wine that is detectable only on the palate. Prior to veraison, the ratio of tartaric and malic acid in grapes are equal but as malic acid is metabolized and used up by the grapevine, the ratio of tartaric sharply increases.


Crystalline deposits of the tartaric acids that precipitate out of the wine over time or through exposure to cold temperatures such as the process of cold stabilization. At KJ we utilize at minimum 3 weeks of cold stabilization for all of our wines.


An abbreviation for trichloroanisole which is the prime cause of wines developing the wine fault of cork taint.


The charring of the wine staves during cask manufacture or rejuvenation.


The process of filling the headspace that is created inside a barrel through wine evaporation into the barrel wood.

Total acidity

The total amount of acidity (Tartaric, latic, malic, etc) in a wine as measured in grams per liter.

Traditional method

A method of sparkling wine production associated with the Champagne wine region where wine undergoes secondary fermentation in the exact bottle that will be eventually sold to the customer.

VA lift

Winemaking technique where the volatile acidity of a wine is deliberately elevated in order to enhance the fruitiness of wines that are meant to be consumed young.


An aldehyde found naturally in oak that imparts a vanilla aroma in wine.


A wine made from a single grape variety

Vin de presse

The dark, tannic wine produced from pressing the cap of grape skins.


A sour-tasting, highly acidic, liquid made from the oxidation of ethanol in wine, cider, beer, fermented fruit juice, or nearly any other liquid containing alcohol.


The process of making grape juice into wine.


Used to measure alcohol from 0-25%.

Volatile acidity

Acids that are detectable on both the nose and the palate. The level of fatty or volatile acids in a wine that are capable of evaporating at low temperatures. Acetic and carbonic acids are the most common volatile acids but butyric, formic and propionic acids can also be found in wine. Excessive amounts of VA are considered a wine fault.

Volatile phenols

Phenolic compounds found in wine that may contribute to off odors and flavors that are considered wine faults. To a limited degree some volatile phenols may contribute pleasing aromas that add to a wine’s complexity, such as ethyl-4-guaiacol which imparts a smoky-spicy aroma.

Wine cellar

A cool (10-15°C), dark location in which wine is stored, often for the purpose of ageing. The best wine cellars have limited temperature fluctuation and an average humidity of 60%.


A device, comprising two vats or receptacles, one for trodding and bruising grapes, and the other for collecting the juice.

Wood lactones

The various esters that a wine picks up from exposure to new oak. These lactones are responsible for the creamy and coconut aromas and flavors that develop in a wine.


A microscopic unicellular fungi responsible for the conversion of sugars in must to alcohol. This process is known as alcoholic fermentation. There are a large variety of yeasts available for wine production. At KJ we typically use EC-1118 and ICV-D254.

Yeast Nutrient

Mainly Diammonium phosphate (DAP), (NH4)2HPO4, this is used to increase the amount of nutrient base that is available for the yeast during a fermentation