Brewing Terms Glossary
Acidification. The process of lowering the pH of a solution until it falls below 7.0 pH.
Acrospire. The embryonic barley plant that grows inside the husk during germination.
Adjunct. Unmalted grain used in making beer; its starch must be converted to sugar by malt enzymes in the mash kettle.
Adsorb. To collect a substance on a surface; for example, protein molecules are adsorbed onto the surface of particles of silica gel.
Aerate. To dissolve air in a liquid.
Albumins. The name for a group of water soluble proteins that coagulate when heated.
Alpha Acid. The soft, bitter hop resin that is responsible for the bitterness of beer. Measured as a percentage of the total weight of the hop cone.
Alpha Acid Content. The percentage of alpha acid in the hop cone. Alpha Acid Units (AAU). The percentage of alpha acid in a given sample of hops multiplied by the weight in ounces of that sample. One ounce of hops with an alpha content of 1 percent contains 1 AAU, or .01 ounce of alpha acid.
Alpha Amylase. A diastatic enzyme produced by malting barley. Attacks the 1-4 links of straight chains.
Amylase. Any enzyme that breaks the bonds that hold starch molecules together.
Amylopectins. The branched chain fraction of starch. Barley contains approximately 73 percent amylopectin and 27 percent amylose.
Amylose Starch. Starch molecules are made up of long strings of glucose or other sugar molecules.
Amyloses. The straight-chain fraction of starch. Barley contains approximately 27 percent amylose and 73 percent amylopectin.
Aroma Hops. Hops used primarily to impart aroma, as opposed to bitterness, to beer.
Aromatic Hops. Hop varieties known for their fine aroma and flavoring properties; also called "noble hops."
Attenuation. The drop in specific gravity that takes place as the wort ferments.
Autolysis. A process in which starving yeast cells feed on each other by excreting enzymes; causes a rubbery stench in beer.
Beta Acid. A soft, bitter hop resin; harsher in flavor than alpha acid but almost insoluble at normal wort pH values.
Beta Amylase. A diastatic enzyme produced by malting barley. Attacks the 1-4 links of straight chains.
Beta Glucanase. An enzyme that breaks the 1-3 links that hold branched starch molecules together.
Bittering Hops. (1) Hops used to add bitterness, but not aroma, to beer. (2) Hop varieties of high alpha acid content, bred for this purpose.
Body. The sensation of fullness or viscosity in the mouth, imparted by malt dextrins and proteins in beer.
Boiling. The step in brewing at which hops are added and the wort is bittered.
Brewing. The craft and science of making beer.
Bright Beer Tanks. Storage tanks for the clarified final beer.
Calcium. An ion that lowers mash/wort pH.
Cane Sugar. Sucrose obtained from sugar cane.
Carbon Filtration. In homebrewing, the dechlorination of a water source by use of a carbon filter.
Carbonate. To inject or dissolve carbon dioxide gas in beer.
Carbonation. (1) Carbon dioxide gas dissolved in a liquid. 2) The process of dissolving carbon dioxide gas in a liquid.
Chloride. An ion that imparts a sweet finish to beer.
Chlorine. Can be used as a sterilizing agent in homebrewing. Also used as a gas added to water supplies to kill bacteria.
Cistern. A vat in which brewers' grain is soaked.
Cold Break. The flocculation of protein and tannin molecules during wort cooling.
Conditioning. The process of carbonating beer.
Copper. An ion that is a vital yeast nutrient at low levels but that can poison yeast at high levels.
Couch. A term that refer to a heap of barley on the malting floor.
Curing. The last step in floor malting, when the grain is heated to fully develop flavor and color.
Decarbonate. To remove carbonate and bicarbonate ions from water, either by boiling or by adding chemicals.
Decoction. A method of mashing that boosts the temperature from one step to the next by removing a portion of the mash, boiling it, and returning it to the main kettle.
Degrees of Extract. A measure of yield used by homebrewers: the specific gravity of one gallon of wort made from one pound of malt.
Dextrinase. An amylolytic enzyme that breaks down the 1-6 bonds that hold dextrins together.
Diacetyl. A powerful aromatic compound that imparts the flavor of butter or butterscotch to beer.
Diastase. A collective term for all the amylase enzymes in malt.
Diastatic Power. A measure of the total amylase content of a given sample of malt; usually expressed in degrees Lintner.
Dimethyl Sulfide (DMS). A powerful aromatic compound that imparts a sweet creamed-corn smell to lager mashes. In finished beer it imparts a malty quality or, at higher levels, the taste of cooked vegetables.
Distillation. Removes all ions from water.
Draff. The solid matter remaining in the mash tun after the malt starch has been converted to sugar.
Endosperm. The nonliving part of the barley grain, which contains starch and protein to feed the growing acrospire.
Enzyme. A complex protein that has the ability to form or break a particular chemical bond.
Esters. A class of compounds formed by joining an alcohol and an acid; many have powerful fruity aromas.
Extract. (1) Malt extract. (2) The sugar derived from malt during the mashing process.
Fatty Acids. Acids based on a string of carbon atoms; they often have unpleasant flavors.
Fermentation. A process in which yeast obtains energy in the absence of oxygen by breaking sugar into carbon dioxide and alcohol.
Fermenter. A generic term for any open or closed vessel in which primary and/or secondary fermentation take place.
Fines. The finely crushed, flourlike portion of the draff.
Flocculation. The clumping together of protein molecules or yeast cells to form relatively large, irregularly shaped particles.
Flocculence. The clumping of yeast cells into masses toward the end of the fermentation process. When the yeast flocculates, it contributes to the clarification of the beer.
Floor Malting. A traditional germination method that calls for the steeped barley to be spread over a flat surface in order to germinate for approximately 13 days.
Fluoride. An ion sometimes added to drinking water in communities across the United States but which has little or no effect on the outcome of beer brewed with that water.
Fusel Alcohol. Any alcohol of higher molecular weight than ethanol (drinking alcohol). Fusel alcohols impart a harsh, clinging bitterness.
Gelatinization. The process in which particles of starch break up and disperse in hot water to form a thick suspension.
Globulins. Large protein molecules that are insoluble.
Grain Sugars. Sugar products derived from grain, intended for use as adjunct equivalents for extract-based beers.
Grist. The crushed malts and adjuncts that are mixed with hot water to form the mash.
Heat Exchanger. A piece of brewing equipment used for heating or cooling the wort or beer rapidly.
Hop Oil. A mixture of volatile aromatic compounds found in the lupulin glands of the hops; imparts hop flavor and aroma to beer.
Hops. The flowers (or cones) of the female hop plant, used in brewing.
Hot Break. The flocculation of protein and tannin molecules during boiling.
Hot Side Aeration. Aerating wort on the hot side of the brewing process; leads to oxidation of the finished beer.
Hydrocarbon. Any compound made up entirely of carbon and hydrogen atoms.
Hydrolysis. The process of breaking peptide or other bonds using a water molecule.
Infusion. A mashing method in which grain is mixed with hot water and the mixture is not boiled. See also Single Infusion, Step Infusion.
International Bittering Units (IBU). A measure of the actual bitterness level of beer. 1 IBU = 1 part per million of isomerized alpha acid.
Ion. An atom or bound group of atoms that carries an electrical charge. Water contains ions that affect enzyme activity in the mash, and others that affect beer flavor.
Iron. An ion that causes haze and hampers yeast.
Isomerize. To alter the arrangement - but not the kind or number - of atoms in a compound by heating or other means. During boiling, alpha acids are isomerized and these isomers (iso-alpha acids) bitter the finished beer.
Kettle. A large vessel, similar in shape to a mash tun, usually made of copper or stainless steel in which the wort is heated. Also called a "brew kettle."
Kiln. A large furnace with a perforated floor heated by either fire or heaters through which malt is dried and roasted.
Kraeusen. (German, literally "crown.") (1) The large head of foam that forms on the surface of the wort during the early stages of fermentation. (2) A method of carbonation in which green beer in the kraeusen stage is added to finished beer to bring about a second fermentation.
Lager. (1) To store beer at low temperatures for a period of weeks or months prior to consumption. (2) Beer that has been lagered.
Lauter Tun. A large vessel with a perforated false bottom. It is used to strain the sweet wort off the spent grains after mashing.
Lead. An ion that causes haze and is toxic.
Lovibond. The scale on which malt, wort, and beer color are usually measured.
Lupulin Glands. The tiny yellow sacs found at the base of the petals of the hop cone. They contain the alpha acids, beta acids, and hop oils.
Magnesium. An ion that lowers mash and wort pH but also implants a clinging "bite" to the finished beer.
Malt. Barley or other grain that has been malted.
Malt Extract. Sweet wort that has been concentrated into a thick syrup or dry powder by removing most or all of the water, and packaged for use by homebrewers.
Malting. The process of soaking, sprouting, and then drying barley (or other grain) to develop its enzyme content and render it suitable for mashing.
Malto-Dextrin. A general name for unfermentable soluble carbohydrates formed by the diastatic hydrolysis of malt starch.
Manganese. An ion important in trace amounts for proper enzyme action in the mash. Large quantities impart a metallic taste to beer.
Mash. (1) To mix a grist with hot water, and allow the malt enzymes to convert the grain starch to sugar. (2) The mixture itself.
Mashing-In. The initial stage of mashing; the process of mixing grist and water.
Mealy. A chewy characteristic of the grain, which is attained only when malt is fully modified. Maltsters use the bite test as means to test malt for full modification. If the grain is mealy, it is considered to be fully modified.
Mild Ale Malt. British malts kilned at high temperatures that produce beers of golden and amber colors. Used specifically in the production of mild ales.
Modification. The sum of the changes that take place in the barley grain during germination (sprouting). Chief among these are the softening of the endosperm and the development of enzymes.
Naturally Conditioned. Carbonated by a second fermentation in the bottle or cask.
Nickel. An ion that causes foaming in beer.
Nitrate. An ion that, while harmless in itself, can be reduced to nitrite by certain "wort spoiler" bacteria.
Nitrite. An ion that interferes with yeast metabolism.
Nitrogen Content. The percentage of the weight of barley or malt that is nitrogen. Protein content of the grain is about 6.25 times the nitrogen content.
Original Gravity. The specific gravity of a wort prior to fermentation.
Oxidation. Any chemical reaction in which oxygen combines with another substance. Oxidation of finished beer produces unpleasant flavors.
Palate Fullness. See Body.
Pale Ale Malt. Considered to be the standard British malts used specifically in the production of pale ales.
Pelletized Hops. Hops that have been dried, powdered, and pressed into pellets.
Peptones. Soluble proteins of moderate size, intermediate between polypeptides and albumins.
pH. The measure of acidity or alkalinity; 7 is the neutral point of the scale, with lower values being acid and higher values alkaline.
Phenolic. Any compound based on a ring of six carbon atoms joined by alternating single and double bonds. The tannins contained in grain husks are phenolic in nature, as are the soft hop resins (alpha and beta acids).
Phytase. An enzyme common in malt, and most active at 80 to 128 degrees. It breaks down phytin into phytic acid.
Phytin. A complex organic phosphate containing both calcium and magnesium. Pale lager malt is rich in phytin.
Piece. Refers to the volume of germinating barley.
Pitch. To add yeast to a cooled wort.
Polymerize. To link together, as in the polymerization of tannins.
Polypeptides. Small soluble proteins consisting of a few amino acids linked together.
Polyphenols. Complex compounds based on two or more phenolic rings joined together. The malt tannins derived from the husk are more properly termed polyphenols.
Potassium. An ion that at high concentrations inhibits certain enzymes in the mash.
Priming. Adding sugar to a finished beer in order to produce carbonation by a second fermentation in the bottle or cask.
Proteolysis. Protein breakdown. The hydrolysis of a protein molecule into amino acids by proteolytic enzymes.
Proteolytic Enzyme. An enzyme that hydrolyzes complex proteins into simpler soluble proteins.
Rack. To transfer wort or beer from one container to another in order to separate it from the sediment on the bottom of the first container.
Recirculation. The action of pumping the wort from the bottom of the mash tun and letting it fall into the surface of the mash. Also called the "Vorlauf."
Respiration. The process in which living things oxidize sugar in order to obtain energy.
Rouse. To make a yeast starter using sterile wort and N to G of the normal pitching slurry.
Saccharomyces Carlsbergensis. Commonly known as "lager yeast."
Saccharomyces Cerevisiae. Commonly known as "ale yeast."
Salt. The common name for sodium chloride, or table salt. In brewing terms, any compound produced by the reaction of an acid with an alkali.
Sanitary. Clean and practically free of microbes, so that it poses no danger of infecting something that comes into contact with it.
Silicate. An ion that causes haze.
Single Infusion. More properly, single temperature infusion; the classic British method in which the mash is mixed and held at a single temperature until starch conversion is complete.
Six-Row Brewers' Malt. A variety of barley having three rows of fertile spikes at each node, on which six rows of grains are formed. Less developed than 2-row barley, it yields less extract.
Sodium. An ion found in water that has little or no chemical effect on beer, although it can create unpleasant flavors.
Sparging. (1) Rinsing the draff with hot water in the lauter tun in order to recover the sugar it holds. (2) The entire process of obtaining clear sweet wort from the mash, including runoff, recirculation, and rinsing.
Specialty Malt. A term used to describe malts other than the standard brewers' malts. Usually used in very small quantities to impart flavor and sometimes color to the final product.
Specific Gravity. The weight of a liquid compared with an equal amount of pure water. The scale is absolute, that is, a specific gravity of 1.050 means the liquid weighs 1.05 times as much as an equal amount of water.
Standard Mash. A mash made in a brewer's laboratory using specified amounts of water and malt.
Starter. A small volume of wort to which yeast is added, in order to activate it before it is pitched into the main batch.
Steely. In malting, a description used for the hard endosperm of the grain at the onset of germination.
Steeping. The action of soaking hard dry barley grains in water in order to soften them. Steeping is best accomplished in stages separated by air rests.
Stewing. A process used by maltsters to create specialty caramelized malts.
Strike Heat. The temperature of the mash water before the grist is mixed into it.
Style. The whole sum of flavor and other sensory characteristics by which individual beers may be placed in categories for purposes of comparison. Beers of the same style have the same general flavor profile.
Sulfate. An ion that imparts a sharp "dry" edge to beers.
Tannins. See Polyphenols.
Terminal Gravity. The specific gravity of a beer after fermentation is complete.
Tin. An ion that causes haze.
Titration. A measurement that gives brewers the total acid content of a solution.
Total Acidity. The measure of the actual amount of acid in a given volume of water. It is found by titration.
Total Alkalinity. The measure of the actual amount of alkali in a given volume of water.
Trub. The sediment formed by the hot and cold break on the bottom of the kettle (hot trub) or the cooling or fermenting vessel (cold trub).
Two-Row Brewers' Malt. A variety of barley on which only the central piece of each triad is fertile, forming two rows of grains each.
Underletting. Filling the space beneath the false bottom of the lauter tun with hot water before putting in the mash.
Volatile. Capable of vaporizing at low temperatures.
Whirlpool. A piece of equipment used for the clarification of beer, usually consisting of a large cylindrical tank. The wort is introduced at high speed through a pipe. As the wort comes into the tank, the trub or hot break deposits as a cone at the bottom by a process of sedimentation.
Whole (Leaf) Hops. Hops that have been dried and compressed but retain their natural form.
Wild Yeast. Any yeast strain that is not deliberately selected and introduced into the beer by the brewer.
Wort. The solution of malt sugars, proteins, and other substances that is produced by mashing.
Wort Chiller. A piece of equipment used to cool the wort rapidly.
Yeast. A single-celled fungus capable of fermentation.
Yield. The percentage by weight of the malt that will be converted into soluble substances (chiefly sugars) in the mash kettle. Determined by making a standard mash.
Zinc. An ion that is a yeast nutrient but that at high levels gives a metallic taste to beer.