Homebrew Glossary - Terms & Definitions

A
ACETIC ACID
The primary acid in vinegar. Created by a wild bacteria (acetobacter) which, in the presence of oxygen, metabolizes ethanol into acetic acid. The presence of this substance in noticeable quantities spells doom for a batch of wine or beer. It can be avoided by careful sanitation techniques and closed fermentors with minimal air space. Wine seriously infected with acetobacter can be made into good vinegar if the winemaker is willing to swallow his/her pride and jazz up his/her salads.

AEROBIC FERMENTATION
Fermentation in the presence of oxygen. Yeast may metabolize with or without the help of oxygen, although alcoholic fermentation is associated with anaerobic fermentation. The presence of oxygen in the first few days of fermentation aids in the synthesis of important structural components of yeast cells, helping the yeast achieve appropriate population levels for active anaerobic fermentation to begin.

ADJUNCTS
Any secondary source of starches and/or sugars used in brewing, the primary source being malted barley (or wheat). Adjuncts include (but are not limited to) flaked cereal grains, sugars, syrups, corn, and rice. The lack of malt flavor in major American beers is due to their use of high proportions of adjuncts, which generally add 100% fermentable sugars. These sugars are completely fermented to alcohol during fermentation, leaving no residual flavor or body. The similar lack of hop flavor in major American beers is due to their use of virtually no hops.

AIRLOCK
Most commonly a plastic water lock which allows the carbon dioxide produced by fermentation to escape, while preventing the influx of outside air (which may carry infectious microbes). A blow-off tube can also be used as an airlock during primary fermentation.

ALCOHOL
Actually a family of organic compounds, the common term "alcohol" refers to Ethyl Alcohol or Ethanol, CH3CH2OH. Alcohol is poisonous by degree to lifeforms small and large, which accounts for the preservative qualities and the hangover potential of any alcoholic beverage.

ALCOHOL CONTENT
The percentage of alcohol in a wine or beer. It may be measured as the percentage of the total volume (Alcohol By Volume, ABV), or as the percentage of the total weight (Alcohol by Weight, ABW). Since alcohol is less dense than wort and water, Alcohol by Volume is the higher of the two values.

ALKALINITY
The opposite of acidity, alkalinity is the prevalence of ions which neutralize H+ ions. A "base" is highly alkaline, or "basic." Usually alkalinity is due to OH- ions which can neutralize H+ ions, although other bases can be responsible for alkalinity.

ALL-GRAIN BREWING
The use of raw malted barley as the primary source of malt sugars in a brewing session, as opposed to the use of malt extracts. Since all-grain brewing requires mashing and sparging, it is considered the "advanced" form of homebrewing.

AMELIORATION
Adjustment or correction of a wine must before fermentation, usually referring to addition of sugar or acid where lacking in the original fruit.

ANAEROBIC FERMENTATION
Fermentation in the absence of oxygen, whereby yeast harvest matter and energy by processing sugar into alcohol, carbon dioxide, and important flavor byproducts.

AROMA
The component of flavor perceived in the nose--in fact, it's often called the "nose." Since the tongue can only express four attributes of flavor (sweet, salty, sour, and bitter), aroma is extremely important in the perception of flavor. This fact is brought to the forefront whenever a person with a stuffy nose eats food, which in the absence of aroma seems completely devoid of flavor. In wine jargon, aroma and bouquet are closely related.

ASTRINGENT/ASTRINGENCY
The mouth-puckering or mouth-drying quality of a wine or beer. Often perceived as extreme "dryness," as in Cabernet Sauvignon wines. Astringency is related to tannins leeched from the skins of the grapes or fruit, or secondarily from the stems and seeds or oak barrels. The astringency of these tannins mark the major differentiation between white and red wine, after color. Although harsh in abundance, tannins help prevent oxidation and can extend the complexity and aging potential of a wine. It is for this reason that most wines suitable for long-term aging are based on highly tannic grapes. Harsh astringency in a young red wine can be softened somewhat by allowing the wine to "breath" before being enjoyed. Decanters are often used for this purpose.

ATTENUATE / ATTENUATION
The ability of a yeast strain to ferment the sugars in a wort or must. Attenuation is more important in brewing, where a blend of complex wort dextrins and sugars must be broken down by the yeast during fermentation. Variations in yeast strain attenuations and brewing conditions will affect the dryness and body of the finished beer. See also, Flocculation.

B
BALLING
Also known as "Brix." The Balling scale on a hydrometer is commonly used by winemakers and commercial brewers in the same way the Specific Gravity scale is used by Brewers. The Balling scale estimates the percentage by weight of dissolved solids in the solution. That is, a reading of 19o on the Balling scale shows that the solution is composed of approximately 19% solids by weight. The "solids" are almost completely sugars, and the use of the balling scale assumes the reading to be synonymous with sugar content. Most wines begin in the 19o to 24o balling range, and ferment out to just below 0o. The Balling scale can thus be used to estimate alcohol content, since roughly one percent of alcohol is created for each reduction of two degrees balling. A hydrometer with a Potential Alcohol scale measures alcohol content more precisely.

BARREL, OAK
Oak barrels are traditionally used to age certain wines, imparting the flavor of oak while allowing very slow evaporation and mild oxidation which can increase a wine's complexity and flavor. The use of oak adds another dimension to a wine's flavor, beneficial in most full-flavored red wines and some whites (e.g. Chardonnay). The characteristic flavors of American versus French oak are considered when choosing barrels. The amount of "charring" or "toasting," where the barrel staves are exposed to direct flames during their manufacture, is also important to the flavor.
Oak cooperage and barrel aging add time and expense to the winemaking process, and oak barrel use is one factor distinguishing more expensive wine from cheaper wine. Home winemakers can avoid the high cost of oak barrels by adding oak chips to their secondary fermentors. However, not all of the beneficial features of barrel aging are achieved with this method.

Oak barrels are also involved in the fermentation of some beer styles, including Belgian Lambics authentic English Real Ales.

BARREL (UNIT OF BEER VOLUME)
A barrel, 31 U.S. gallons, is the basic unit of measurement for commercial beer production. The kegs commonly sold to bars and consumers are 1/2 barrel and 1/4 barrel in capacity (hence the terms"1/2 Keg" and "1/4 Keg").

BLOW-OFF TUBE
Large-diameter length of tubing used to allow the escape of the carbon dioxide and the krausen or cap during active fermentation. When closed off on one end by the fermentor, and on the other end by a pail of water, a blow-off tube serves as an effective airlock.

BODY
Refers to the fullness or mouth-feel of a beverage. In beer, body is the result of residual malt sugars, dextrins and alcohol. In wine, body is a combination of alcohol, tannins, and other solids in the wine.

C
CARAMEL MALT
See Crystal Malt.

CARBON DIOXIDE
The gas byproduct of fermentation. The creation of CO2 during primary fermentation protects beer and wine from oxidation and infection. After fermentation, residual carbon dioxide is responsible for the "fizz" or effervescence in beer and sparkling wine.

CARBONATE / CARBONATION
To infuse a wine or beer with dissolved carbon dioxide gas. CO2 produced as a major byproduct of fermentation is responsible for the natural carbonation found in sparkling wine and many craft beers. Beer and wine may also be "force" carbonated by applying pressurized gas to the solution.

CARBOY
A fermentor in the shape of a drinking water tank, the advantage of which is minimal surface area exposed to air contact (which can lead to oxidation and infection). Glass carboys are preferable to plastic due do their impermeability to air and their ease of cleaning. Both glass and plastic carboys are available in several sizes, the standard size being 5 gallons.

CITRIC ACID
The primary acid in oranges and lemons.

CLARIFY
To cause or allow haze-causing particles and solids to precipitate out of solution, with or without the help of finings, or to filter wine or beer. Clarified beer or wine is often called "bright" or "brilliant." Usually, the haze-causing particles have no effect on flavor, and clarification is merely a cosmetic process.

CONCENTRATE
To process a wort or grape juice using boiling and/or vacuum evaporation, or the product thus formed. Concentration of juice and wort allows easier packaging, extends aging capabilities, and reduces shipping costs. Concentrated wort is available to homebrewers as malt extract, which significantly reduces the time and equipment needed for brewing. Similarly, grape concentrates are a convenient alternative to fresh grapes for those who live far from a winegrowing region.

CRAFT BREWING
A newer, less commonly used term for "Microbrewed" beer, since most "Microbrewed" beer is made by breweries whose output now dwarfs the traditional definition of "Microbrewery," which is 15,000 barrels per year. Craft breweries generally produce all-malt beers from quality ingredients, emphasizing flavor and individuality rather than industrial-style costcutting and marketing gimmicks. The term may apply to a brewery as small as your kitchen to one as large as the Boston Beer Company (makers of Samuel Adams). It is interesting to note that, although the craft brewing scene in America has enjoyed remarkable growth in the last decade or so, craft beer still commands only 3% of the beer market share in America.

CRYSTAL MALT
One of the three main categories of brewing grains. Crystal malts are created by the maltster by steeping wet grains to achieve the production of sugars within the whole grains. When the grains are then dried and heated in kilns, the sugars are crystallized and caramelized to varying degrees of darkness. Since crystal malts do not require mashing, they may be used by malt extract brewers and all-grain brewers alike.

D
DEXTRIN
Basically a short starch molecule. During the malting and mashing processes, starch in the brewing grain is broken down into dextrins and malt sugars. Residual dextrins contribute to the body of a beer, and isolated "malto-dextrins" are available as an additive. The name "Dextrin" also applies to a particular type of crystal malt (a.k.a. CaraPils) which contributes a high proportion of these compounds to the beer.

DISGORGING
The removal of the yeast sediment from the bottle neck during the making of sparkling wine or "champagne." Since sparkling wine must undergo a fermentation in the bottle to produce carbonation, the bottles contain yeast in abundance. Disgorging is a means of removing this yeast sediment while containing the carbon dioxide within the bottle. It usually involves freezing the bottle neck before opening the bottle, removing the sediment, and recorking.

DISTILL
Distilling is a process of heating an alcoholic beverage and condensing the high-alcohol vapors, producing a much stronger solution by leaving behind much of the water in the original drink. Due to the tendency to produce toxic forms of alcohol in unknown proportions, distilling beverages in the United States requires a commercial license.

DRY / DRYNESS
Referring to an alcoholic beverage, "dry" is defined as "not sweet." Beer yeast strains will ferment different proportions of the malt sugars present in a wort, leading to different levels of dryness. Wine yeast will generally ferment all of the simple sugars present in a wine must, unless measures are taken to halt fermentation. Home winemakers who desire a sweet wine must stabilize their wine before sweetening, to prevent in-bottle fermentation.

DRY HOPS/DRY HOPPING
"Dry hops" are any hops added to a beer during or after fermentation. Since these hops are not exposed to boiling (or even hot) wort, the bittering acids from the hops are not effectively extracted. However, the aromatic oils responsible for hop aroma are extracted, and in an unadulterated state that many feel expresses the true character of a good hop variety. Although dry hopping is typical of many beer styles, the technique is most commonly associated with the Pale Ale style and all its subcategories.

F
FALSE BOTTOM
A raised perforated platform in a lauter tun, designed to allow for drainage of sweet wort during the sparge while retaining the grain bed. False bottoms range from fitted metal screens to perforated plastic domes to simple mesh bags.

FERMENTATION
The process whereby yeast metabolizes sugars into energy, alcohol, carbon dioxide, secondary byproducts, and more yeast. Brewers and winemakers alike make a distinction between primary and secondary fermentation.

FERMENTATION LOCK
See Airlock.

FERMENTER
Any yeast or human who engages in fermenting sugar-laden liquids into alcoholic drinks. As opposed to a fermentor, the container to which the human adds the yeast and the sugar-laden liquid.

FERMENTOR
A container used to hold fermenting wort or must as it turns into beer or wine, respectively. Commercially, fermentors are usually composed of stainless steel . Home beer and winemakers generally settle for plastic buckets or glass carboys. See also, fermenter.

FILTRATION
Forcing wine or beer through a porous material capable of trapping larger particles (including yeast, haze-causing proteins, etc.). Filtration of beer removes the yeast, requiring either forced carbonation or the addition of more yeast for natural carbonation. Filtration of wine is almost standard in the commercial winemaking community, but less common in home winemaking due to the tendency to oxidize or otherwise adversely affect the wine. Alternatives to wine filtration are patience, clarifiers, and cold-conditioning.

FINING / FININGS
The use of additives which clarify wine or beer by causing suspended particles to clump and precipitate. Also refers to the additive itself. In the history of winemaking, finings have included milk, eggs, ox blood, isinglass (from the stomach of sturgeon), gelatin, clay, and small particles of charged plastic.

FLOCCULATION
The tendency of a yeast strain to clump together and precipitate from solution, thereby clarifying the beer or wine. Ability to flocculate is an important quality of yeasts used for brewing and winemaking (as opposed to baking yeasts). Traditional methods developed in the Champagne region of France require flocculant yeast strains which settle in the neck of the overturned bottles, where they may be removed before the wine is sold. Highly flocculant strains may produce stuck fermentations if temperatures dip below the recommended level. See also, Attenuation.

FORTIFY / FORTIFICATION
To supplement the alcohol content of a wine with spirits, usually brandy. Fortified wines, usually containing 15% to 21% alcohol, include Port and Sherry.

G
GRAVITY
A reference to the specific gravity of a beer or wine. Gravity may at times refer to "Gravity Points", which are the units of the reading which follow the decimal point. That is, a wort with a specific gravity of 1.045 has 45 gravity points, and a wort with a gravity of 1.105 has 105 points. Since gravity points effectively remove the "water portion" of a specific gravity reading (water being 1.000 in gravity), they isolate the sugar content of the wort. This facilitates the mathematics of beer, where the amount of sugar each ingredient adds to the wort may be measured or predicted using points per pound per gallon (p/p/g). This technique is the principle behind the original gravity portion of the brewer's calculator.

GRIST
In all-grain brewing, "grist" refers to the mixture of crushed grains (and adjuncts, when used) which are the raw material for the mash. Mashing begins when the hot liquor is mixed with the grist.

H
HOPS
The hops used in brewing are the flower of a tall-growing vine of the same name. The green buds are covered with lupulin glands, tiny sacks containing acids and aromatic oils which provide the bitterness and aromatic qualities hops are prized for. Along with balancing the flavor of beer and enhancing its aroma, hops act as a preservative by inhibiting many potentially spoiling organisms.

HYDROMETER
A floating graduated glass instrument which uses relative density to measure approximate sugar content in a must or wort. The hydrometer is useful for determining the quality of the wort or must, monitoring the progress of fermentation, and estimating alcohol content. A "Triple-Scale" Hydrometer will have scales for Balling or Brix, Specific Gravity, and Potential Alcohol.

K
KRAUSEN
The foamy, dirty head of bubbles, yeast, and fermentation by-products floating on the top of an actively fermenting beer. Some believe that removal of the krausen improves the final beer's flavor. Since the krausen has a tendency to clog airlocks (sometimes leading to exploding fermentors), blow-off tubes can be substituted during primary fermentation.
"Krausening" refers to the addition of freshly fermenting wort (that is, wort with a krausen) to a previously fermented batch just before it is bottled. Krausening will carbonate the packaged product, and produce a freshness of flavor not found in artificial carbonation methods or natural priming with residual yeast.

L
LAUTER TUN
Any vessel used to hold all-grain brewing ingredients during the lauter (sparge). Lauter tuns must contain a false bottom to allow drainage of sweet wort while retaining the grain bed. However, anything from a brewing kettle to nested plastic buckets will do, provided a false bottom set-up is created. Many lauter tuns are equipped with sprinklers above the grains to allow an even spray of sparge water over the grain bed.

M
MALO-LACTIC FERMENTATION
A process important in winemaking whereby a common bacteria strain ferments malic acid into lactic acid (a mild acid found in milk). Because lactic acid is a much weaker acid, this process reduces the acidity of the wine. Byproducts of "M-L fermentation" are sometimes said to add buttery overtones or additional complexity to the wine.

MALT
In brewing, the noun "malt" generally refers to the sugars extracted from malted cereal grains (usually barley or wheat). Malt is available as a concentrated syrup or powder that most homebrewers reconstitute to create their wort. Malt is also the term for the malted grains all-grain brewers use to extract their wort sugars.
"Malting" itself is the process whereby the raw grains are soaked, allowed to germinate (sprout), heated, and then dried. This process is produced by malting companies, commonly known as "maltsters." Malting stimulates the creation of enzymes crucial to mashing and begins the process of chemical breakdown necessary to create sweet, fermentable wort from raw grains. Various malting techniques create the three major categories of malted grains: Base or Pale Grains, Crystal or Caramel Malts, and Roasted Grains.

An "all-malt" beer, favored by home brewers and commercial craft brewers, will be created from an all-malt wort, rather than one including cheaper adjuncts produced from corn or rice.

MALT EXTRACT
A form of concentrated brewer's wort used by most homebrewers as their main source of malt sugars (as opposed to all-grain brewing). Malt extract comes in both syrup and powder forms, and may or may not include hop flavoring.

MASH/MASHING
The first major phase of all-grain brewing (before sparging), where the crushed malted (and occasionally unmalted) grains are soaked in water and steeped for various times in specific temperature ranges. During these "temperature rests", the natural enzymes present in the barley (and active at the specific temperature) break down starches and/or proteins. Mashing is the completion of a process begun by the maltster, at the end of which the final sweet brewer's wort has been extracted from what were once raw cereal grains.

MASH TUN
Any vessel used to hold all-grain brewing ingredients during the mash. Mash tuns range from simple brewing kettles and igloo coolers to combination mash/lauter tuns equipped with false bottoms and heating devices.

O
OXIDATION
The adverse effects of exposure to oxygen, whereby oxygen transforms various wine and beer components into compounds which taste harsh or stale. The browning of an apple after it is bitten or cut is a good visual example of the rapid deterioration caused by oxygen exposure. Along with microbiological stability, reduced oxidation is the reason carboys and airlocks are required for secondary fermentation of beer and wine.
Oxidation is related sometimes to "aeration" and "oxygenation," which refer to the advantageous influx of oxygen preceding active fermentation.

OXYGEN
The importance of oxygen in brewing and winemaking cannot be overestimated. Due to oxygen's prevalence and high electronegativity, it readily reacts with the organic compounds found in beer and wine--usually producing irreversible damage. Oxygen is the primary cause of "staling" in beer and "browning" in wine. After primary fermentation, oxygen exposure should be avoided at all costs to avoid oxidation.

OXYGENATION
Oxygen exposure before primary fermentation is generally advantageous, since yeast can use oxygen to synthesize many of the fatty acids and sterols required to reproduce themselves. The oxygen dissolved before fermentation by the methods of aeration is generally consumed by the yeast or displaced by carbon dioxide during primary fermentation.

P
pH
A measure of the free H+ ions in a solution, with 7 (the pH of distilled water, an equal solution of H+ and OH- ions) being neutral. Since it is based on a negative logarithm, lower numbers will have higher concentrations of H+, which is acidity. Higher pH numbers will have lower concentrations of H+ and higher concentrations of OH-, or alkalinity. pH is important in all-grain brewing due its effect on enzyme activity during the mash. In winemaking, pH is measured to assure proper fermentation characteristics, acidity levels, and preservative qualities. pH is not a measure of total acidity, although the two are related.

POTENTIAL ALCOHOL
A scale on the hydrometer which treats the estimated sugar content as "pre-alcohol." As fermentation continues, the alcohol content (by volume) can be estimated by subtracting the current potential alcohol reading from the original one.

PRIMARY FERMENTATION
The most noticeably active phase of fermentation, usually beginning one to three days after pitching the yeast. Primary fermentation is marked by the presence of a krausen or cap caused by the rapid escape of carbon dioxide. Once the sugars are substantially depleted, the activity slows and secondary fermentation begins.

PRIMING
Adding sugar or malt to a fermented beer before packaging, creating a renewed fermentation in the bottle or keg, which produces carbonation in the finished product.

R
RACK / RACKING
Winemaker's term for the syphoning of wine from one fermentor to another, removing the wine from its lees.

ROASTED MALT / ROASTED GRAINS
One of the three major categories of malted grains available for brewing, along with base malts and crystal malts. Roasted malts are kilned at high temperatures for extended times, creating much darker colors and coffee/burnt flavors than in other grains. Roasted grains are most important to the darker styles like Porter and Stout. Since roasted malts do not require mashing, they may be used by malt extract brewers as well as all-grain brewers.

S
SACHAROMETER
A hydrometer as used to measure sugar content, as in the Balling (Brix) scale.

SECONDARY FERMENTATION
The period of fermentation and aging (or lagering) which follows primary fermentation. During secondary fermentation, the remaining fermentable sugars are fermented and the beer or wine begins to clarify and age. Secondary fermentation must be complete before the wine or beer is packaged.

SOUR / SOURNESS
Flavor perceived on the tongue and caused by the acidity of a wine or beer. Some acidity is as essential part of the "backbone" or "structure" of a wine, providing a crispness of flavor important in wine. Acidity also contributes to the aging potential of wine. White wines are generally slightly more sour or acidic than reds, often balanced by residual sugar. Red wines are generally more tannic.
Sourness is also associated with some unique beer styles, especially Belgian Lambics.

SPARGING
The second major phase of all-grain brewing (after mashing), where the sweet wort is separated from the spent grains. The water already in the mash, plus additional hot sparge water, is allowed to slowly soak through the grain bed, absorbing the sugars from the husks and passing them into the brewing kettle. Sparging requires a lauter tun.

SPECIFIC GRAVITY
The Specific Gravity scale on a hydrometer is commonly used by brewers and some winemakers to measure the sugar content of the wort or must. The scale is based on density relative to water. Pure water at the calibration temperature (usually 60o F) measures 1.000 on the Specific Gravity scale. If exactly one gallon of pure water was weighed next to exactly one gallon of a solution with a S.G. of 1.048, the second gallon would weigh 1.048 times the weight of the gallon of water. Because Specific Gravity relates to sugar content, alcohol content can be estimated from the change in Specific Gravity caused by fermentation. A triple-scale hydrometer will have a Potential Alcohol scale for just this purpose.

STABILIZE
To prepare the wine for long term storage by allowing all microbiological activity to cease or by disabling the yeast with additives. Potassium sorbate and sulfites are often added to the wine before bottling due to their effectiveness in preventing renewed fermentation, microbiological activity, and oxidation. If a wine is to be sweetened before bottling, stabilization with Potassium Sorbate (Sorbistat K) is required.

STARCH
Chemically, starch is a long molecular chain composed of linked units of sugar. The grains used for brewing are seeds loaded with starch as a stored source of energy. This starch (along with protein) will be modified (broken down) in the course of malting and mashing, creating the simple sugars which are the main component of beer wort.

STUCK FERMENTATION
A fermentation which ceases prematurely, usually due to inappropriate temperatures, yeast nutrient deficiencies, or misproportioned ingredients.

SYPHON / SYPHONING
The gravity-powered act of transferring beer or wine from one container to another, or the equipment used to do so. Winemakers and some brewers commonly refer to syphoning as "racking."

T
TITRATION
Measuring the presence of a particular chemical ion or compound by adding a measured volume of a prepared neutralizing solution. Titration using a highly alkaline base and a color change indicator is used by winemakers to measure total acidity.

W
WATER LOCK
See Airlock.

WORT
Pronounced "Wert." A brewer's term for beer before and during fermentation. Winemakers use the analogous term must.

Y
YEAST
Single-celled ascomycetous fungi (!) used to ferment beer and wine. Brewing and Winemaking yeast strains differ from bread yeast in that they are selected for tolerance to alcohol (and sulfites), tendency to attenuate and flocculate, and flavor characteristics imparted by the by-products they produce during fermentation. Yeast is a good source of Vitamin B, which is why Brewer's Yeast (dead) is sold in health food stores.

YEAST NUTRIENT
A mixture of various nutrients, minerals, and dead yeast ("yeast hulls" or "yeast ghosts") which provide the materials necessary for yeast to reproduce and ferment vigorously. Nutrients are helpful in almost any batch of beer or wine, and required in low-nutrient broths like mead.

Z
ZYMURGY
The science of fermentation, like in that of brewing and winemaking. One of the many perks of being brewers and vintners is that we get the last word in the dictionary. "Zymurgy" is also the name of a popular homebrewing magazine.