AAU See Alpha Acid Units
acid malt A malt high in the phytase enzyme, which breaks down phytin into phytic acid, thus lowering the mash pH. Typically only used in Germany, where the Reinheitsgebot prevents brewers from using food-grade acids to do the same thing.
acid rest A relatively low temperature rest (95F) used to activate the phytase enzyme, the desired result of which is to lower the pH of the mash. This is generally only employed in Germany where the Reinheitsgebot prevents the use of things like acid blend which serve the same purpose. A small amount of acid malt is used.
adjunct Any unmalted grain used in making beer. It's starches must be gelatinized and mashed with the enzymes from malted grains, in order to turn them into sugars. It is very undesirable to put unconverted starches into your beer.
aerate To dissolve air in a liquid. Beer wort must be well aerated before pitching to allow for healthy growth and reproduction of the yeast. This can be done in any one of several ways. See here for details.
Alpha Acid Units The percentage of alpha acids in hops multiplied by the weight in ounces of the hops. Also known as Homebrew Bitterness Units (HBU). e.g. 1 ounce of Hallertauer at 5% AA has 5 AAUs
alpha acids Acids present in hops, which give them their desired bittering characteristics. Most commercial hops are sold with a figure representing the percentage by weight of alpha acids (% AA). For example, Hallertauer are typically around 4% AA
alpha amylase One of the two primary enzymes responsible for breaking starch down into sugar. Alpha amylase is most active in the upper range of mashing temperatures (155F-160F) and is responsible for producing higher-order (larger) sugars which are less fermentable, producing a beer with more body.
amylase A group of enzymes (alpha amylase, beta amylase) present in most malted grains which are responsible for converting starches in the grain into both fermentable and unfermentable sugars. Each enzyme has a specific temperature range in which it is most active. The allgrain brewer steps her mash through a series of temperature rests in order to activate these and other enzymes.
aroma hops Hops added very late in the boil to add primarily aroma characteristics to the beer (and virtually no bitterness). Aroma hops are generally (but not always) the noble varieties, which are typically lower in alpha acids.
attenuation A measure of the drop in specific gravity which takes place as the wort ferments. One of the characteristics of yeasts which brewers concern themselves with is the average attenuation, which can range from yeast to yeast. 65% would be a low attenuation, while 85% would be very high. No brewer's yeast ferments all the sugars in the beer. Selecting a yeast strain with a certain average attenuation is another tool the brewer has to control the body of the beer.
beta amylase One of the two primary enzymes responsible for breaking starch down into sugar. Beta amylase is most active in the lower range of mashing temperatures (149F-155F) and is responsible for producing lower-order (smaller) sugars which are more fermentable, producing a beer with less body.
beta glucanase The enzyme which breaks down beta-glucans, which hold together branced starch molecules. This term is most commonly associated with George Fix, who championed the now famous 40/60/70 mashing schedule. The 40C rest breaks down beta-glucans, which in turn has been shown to give higher extraction yields.
bittering hops Hops added at the beginning of the boil in order to obtain maximum alpha acid utilisation. Any type of hops can be used for bittering, although those higher in alpha acids will require the use of less hops per unit of beer.
break see break material
break material The break is the point in brewing when proteins coagulate, making a clearer beer. This happens both when the wort gets boiled, as well as when it chills quickly (see hot break and cold break). The material formed is called either break, or break material. It is generaly accepted that the more break you can get (or force), the better.
carbonation This terms is used to describe both the amount of CO2 in the beer, as well as the process of putting CO2 into the beer. See force carbonation and natural carbonation.
carboy A large glass bottle used by homebrewers for fermenting beer. Typically found in 12 litre (3 US gallon), 19 litre (5 US gallon) and 23 litre (5 UK gallon) sizes.
chit malt This is one of the several tricks that German brewers use to circumvent the limitations of the Reinheitsgebot (German Purity Decree). Under the Reinheitsgebot, only water, hops, malt and yeast may be used as beer ingredients. However, unmalted barley can often produce favourable flavours and properties in beer. So maltsters sometimes begin to malt their barley, but then halt the process almost immediately so that only 1/4 of the grain is modified. The Reinheitsgebot does allow the use of this grain, since technically speaking it has been malted. By these means German brewers can take advantage of some of the desirable properties of unmalted grain, since 3/4 of the husk was not modified by the short malting period.
cold break When the boiled wort is chilled quickly, it forces proteins to coagulate and eventually sediment out. This term is the name of both the process, as well as the material formed. See break and hot break
conditioning The process of carbonating beer.
decoction mashing See here for definition.
diacetyl An aromatic compound most often described as buttery, or butterscotch. There are very few styles of beer in which this is considered an acceptable flavour.
draff The material remaining in the lauter tun after sparging
enzyme A complex protein with the ability to either break or form a chemical bond. Most of the enzymes brewers concern themselves with break bonds.
extraction efficiency A measure of the amount of sugars obtained from the grains during the mash, compared with the theoretical maximum obtainable from the grains used. Note that homebrewers and professional brewers have completely different ways of calculating extraction efficiency, so the two figures they obtain are not directly comparable. See here for details.
final gravity The specific gravity of a wort after fermentation is complete. See also original gravity.
flocculation The clumping together of smaller particles to form larger particals which drop out more quickly. The flocculence of yeast is of interest to brewers. Different yeasts exhibit different degrees of flocculence.
force carbonation Force carbonation is the use of a CO2 tank to carbonate your beer. This requires beer kegs, as well. There are two ways to force carbonate beer : either leave the CO2 tank connected at the desired pressure for about a week, or connect at the desired pressure and shake the keg for 5 to 10 minutes to dissolve the CO2. See carbonation and natural carbonation.
fully modifed see modification
gelitinization The process by which starch molecules break up and disperse themselves evenly throughout the hot water. Of utmost importance when mashing. Full gelitinization of the mash occurs at 149F, and is required to get maximum conversion of starch to sugar.
gelitinize see gelitinization
grain The seeds of grass-type plants (barley, oats,wheat, etc), which can be used for grinding into flour for baking, or can be malted for use in brewing. Some unmalted grains are also used in brewing certain types of beer.
grain bill This is the term used to refer to the total amount and types of grains used in a particular beer recipe. One of my favorite beers has a "grain bill" consisting of 7 lbs 2-Row, 1 lb Malted Wheat, and 1 lb rice.
grant A smaller open-topped vessel placed between the lauter tun and boiling kettle, through which the wort is run during the sparge. It allows the brewer easy access to the wort which is being run off, such that it can be monitored both visually and with various brewing tools such as a thermometer, hydrometer, and pH meter. Most homebrewers do not employ a grant. The grant also allows for a buffer zone between a pump and the lauter tun. If the pump were pulling directly on the lauter-tun, it could compact the grain bed and lead to a stuck sparge. But if the beer is allowed to gravity-flow into the grant, and then the pump sucks on the grant, this problem is avoided.
grist The grains and adjuncts used in the mash
HBU See Homebrew Bitterness Units
Homebrew Bitterness Units See alpha acid units
hop head Someone who likes a very heavily hopped beer.
hops Hops are the cone-like flowers of the female hop vine, and are used to balance the sweetness of the malts with the bittering qualities of the hop resins. See the Hop Page for further details.
hot liquor A bit of a confusing term, since the hot liquor is nothing more than the hot water which will be used in sparging.
hot liquor tank The vessel in which the hot liquor is stored.
hot-side aeration The introduction of oxygen into the hot wort. Generally considered to be a bad thing, as it can lead to oxydized beer later in the process. Some degree of splashing of the mash and wort is unavoidable, and in these cases brewers should worry more about properly mixing, than about hot-side aeration.
humulone The orangey, soft resin in hops which is primarily responsible for the bittering properties of the hops. a.k.a. alpha acid
hydrometer A long, thin glass tube that is weighted at one end and used to measure the specific gravity of liquids such as wort and beer. Use of a hydrometer throughout the brewing process allows the brewer to judge if everything is progressing normally.
IBU See Internation Bittering Units
infusion mashing See here for definition.
International Bittering Units Unlike HBUs and AAUs, which are a measure of the bittering potential of hops, and only an estimation of the amount of bitterness in the actual beer, IBUs are an accurate measure of the actual level of bittering in the beer. Measuring IBUs requires the use of expensive laboratory equipment, although there are several formulas which allow homebrewers to estimate IBUs.
iso-alpha acid Alpha acid after it has been isomerized
isomerize To change a chemical compound into an isomer of the same compound. An isomer has the same chemical formula, but the atoms are arranged in a slightly different fashion. Hops must be boiled for extended periods because alpha acids are not soluable in wort, only iso-alpha acids are. Boiling isomerizes the alpha acids.
kraeusen The large head of foam which forms on top of the fermenting beer in the early stages.
lauter tun The vessel in which lautering takes place. It is usually fitted with either a false bottom or a manifold in order to facilitate the rinsing of the grains.
lautering The step in the allgrain brewing process after the mash, during which the converted sugars are rinsed from the crushed malts and other grains and collected for boiling. Also known as sparging.
Lovibond A measure of the darkness of a malt, wort and beer. Pilsener malts are in the 1 to 3 degrees Lovibond range, Munich malt from 7 to 10, Crystal Malt can be a very wide range from 15 to 100, Chocolate malt starts around 200, and really dark malts like Black Patent can be over 450.
malt Malt is what a grain is called after it has been malted. It's also known as "malted grain"
malting Malting is the process by which Malt is produced. Grains are soaked in water over externded periods, during which they are drained, soaked, drained, soaked and so on. This causes the grain to germinate, or start to grow. Once germinated, the grain rootlet forms at one end, and tunnels beneath the grain husk to the other end of the grain. During this time, changes take place within the grain itself. Certain enzymes are formed which under normal circumstances would help the developing plant turn the starch in the grain seed into food for itself. The maltster will halt this "modification" by kilning the grain at certain temperatures (according to what type of malt is desired). Later, the brewmaster will again soak the grains in a process called "mashing". This allows the brewmaster to re-activate the enzymes, and use them to turn the starches in his mash into sugars for yeast food.
malto-dextrin Unfermentable carbohydrates which add body and head retention to beer.
mash verb : The process by which crushed malts and other grains are placed into a vessel and steeped at various temperatures in order to convert the starches in the grains into sugars.
noun : Term also used for the mass of grain and water as it steeps.
mash in noun : The initial stage of mashing when the grain and water are first mixed.
verb : to initially mix the grain and water
mash out At the end of the final saccharification rest, raising the mash to 165-168F and holding for 10 minutes to denature (kill) the enzymes, and thereby fix the exact composition of the wort. A great number of homebrewers (probably most) do not employ a mashout, even though it can significantly improve extraction efficiency.
mash tun The vessel in which one mashes.
modification See modified
modified The degree of change which has taken place in the grain during the malting process. The endosperm softens, and enzymes develop. The grain can be said to be 1/4 modified, 1/2 modified, 3/4 modified, or fully modified. Non-fully-modified malts require a protein rest when mashing to break down larger proteins. The vast majority of malts used nowadays are fully modified, so the protein rest is not required.
natural carbonation The use of CO2 produced by the fermenting beer to carbonate the beer. For example, when you measure out the desired amount of corn sugar or malt extract for bottling, then seal the bottles, you are employing natural carbonation. This term is a bit of a misnomer since there isn't really any such thing as unnatural carbonation. CO2 is CO2, no matter where it comes from. See carbonation and force carbonation.
Noble Hops Hop varieties stemming primarily from Germany, the UK and the Czech Republic, which have been in existance for a very long time. Most other hop varieties trace their origins to the noble ones. See our hop page.
OG See Original Gravity
Original Gravity The specific gravity of a wort prior to fermentation. See final gravity.
oxidation Any chemical reaction in which oxygen combines with another molecule. Oxidation in finished beer produces unpleasant flavours.
phytic acid
phytase is the enzyme which breaks down phytin into phytic acid.
pitch To add yeast to cooled wort
priming The addition of sugar to fermented beer immediately prior to bottling or kegging. The added sugar ferments in the sealed package, creating the carbonation for the beer.
protease A general term used for the group of enzymes which break down proteins. See protein rest.
protein rest During the mash, a protein rest is employed to activate proteases which break down proteins. The temperature range for this rest is 105F to 132F (40C to 50C). A rest around 122F is commonly employed when non-fully-modifed malts are used, or when a large amount of adjuncts are used. A rest in the 105F-122F range can have a negative effect on head retention if such malts or adjuncts are not used. A rest at 132F can have a positive effect on foam and head retention, no matter what type of malts or adjuncts are used. A protein rest is typically 10 to 20 minutes long.
Reinheitsgebot Literally "Purity Decree". In 1516 the Bavarian king Ludwig declared that beer may only be produced with malt, water and hops (yeast was originally not included because it's existance was unknown at the time). All the German tribes would eventually adopt this decree, so it is today known both as the Bavarian Reinheitsgebot of 1516, as well as the German Reinheitsgebot of 1516. When yeast was later discovered, it was added as the fourth ingredient allowed in beer in Germany. This is in stark contrast to the over 100 ingredients allowed in beer in North America.
rest The period of time during which the mash is held at a pre-determined temperature in order to activate specific enzymes. See protein rest, saccharification rest, acid rest.
sanitary A state of cleanliness where the microbial and wild yeast and bacterial count on the surface of an item is reduced to a level considered safe for brewing. This is achieved by soaking items in a solution of sanitizing agent. See sterile.
sanitize To make sanitary. Items used in a home brewery should always be properly sanitized immediately before use.
SG see specific gravity
sparging See lautering
specific gravity The weight of a liquid as compared to an equal amount of water. The specific gravity of water is 1.000. Dissolving sugar into water increases the specific gravity (often called simply gravity). As fermentation commences, the SG decreases. A wort with an SG of 1.050 weighs 1.050 times an equal volume of water. See also original gravity and final gravity. Brewers use a hydrometer to measure SG.
starter A small volume of wort mixed with yeast. Used to increase the yeast population before introduction into the main wort. Liquid yeast cultures should always be used with a starter, as the population is not nearly sufficient to achieve ideal fermentation. Use of 2 packages of dry yeast gives sufficient population such that a starter is not required.
step infusion See infusion mashing.
sterile Completely devoid of life. No brewery - professional or home - will ever be sterile. See sanitary.
strike temperature The temperature of the strike water.
strike water The water which is used to mix with the grist at mash in.
terminal gravity See final gravity.
trub The flocculated yeast and break material which collects at the bottom of the fermenter.
wild yeast Any yeast strain which was not deliberated introduced into the wort by the brewmaster. Though most wild yeasts are harmful to the beer, a very small minority of them are not.
wort The term used for the beer before the yeast is added.
yeast starter See starter.