The Alcohol Glossary

Compiled by John E. Murtagh, Ph.D.

Please note: All the terms defined in the full Alcohol Glossary are listed here, with definitions of some of them, as samples. For the full Alcohol Glossary, see The Alcohol Textbook or the Worldwide Distilleries Guide.

Bold type is used in the definitions to denote words (or minor variations of words) which are defined under separate entries in the original, full version of this glossary.


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- A -

Abbreviation for Ångstrom.

Absolute Ethanol.
A pharmaceutical term for anhydrous ethanol. It is generally defined as having less than 1 per cent water.

Otherwise known as ethanal, acetic aldehyde or ethylaldehyde. A clear flammable liquid with a characteristic pungent odor. Chemical formula CH3CHO. Boils at 21C and freezes at -123.5C. It is miscible with both ethanol and water. It has a narcotic effect on humans, and large doses may cause death by respiratory paralysis. It is a congener in the production of ethanol by fermentation, and is usually a major constituent of the heads fraction removed in rectification.

Acetic Acid.

A genus of gram-negative, aerobic bacteria comprising ellipsoidal to rod-shaped cells, as singles, pairs or chains. Otherwise known as acetic-acid bacteria or vinegar bacteria, they are able to oxidize ethanol to acetic acid. They may be responsible for loss of yield in ethanol production, if a fermented mash is agitated or aerated excessively.


Acid-Acid Process.

Acid-Enzyme Process.

Acid Hydrolysis.
The hydrolysis of a polymer by the use of acid. In the case of starch hydrolysis, acids may be used as an alternative to enzymes in either (or both) the liquefaction or saccharification processes.

Acid Washing.
A process in which yeast recovered from a finished fermentation is acidified to reduce the level of bacterial contamination, prior to recycling into a new fermentation.




An unaged alcoholic beverage produced in Central and South America by the distillation of beer derived from the fermentation of sugar-cane juice or molasses. It is similar to a crude rum.


A member of a class of organic compounds containing carbon, hydrogen and oxygen. Considered as hydroxyl derivatives of hydrocarbons, produced by the replacement of one or more hydrogen atoms by one or more hydroxyl (-OH) groups. Under the modern IUPAC (International Union of Pure and Applied Chemistry) naming system, the name given to an alcohol is derived from the parent hydrocarbon, with the final "e" changed to "ol". Thus methane-methanol, ethane-ethanol etc. The principal alcohol in fuel and beverage use is ethanol, (otherwise known as ethyl alcohol.)

Alcohol-Fuel Permit (A.F.P.).


Alpha Amylase.
An enzyme used in the liquefaction of starch, in the grain-mashing process, prior to saccharification and fermentation. Alpha amylase hydrolyzes the long-chain starch molecules into short-chain dextrins. These are more suitable for subsequent saccharification by other enzymes to fermentable glucose. (Alpha amylase is an endo-enzyme in that it works from the inside of the amylose molecule, breaking it down more-or-less randomly.) In beverage-alcohol production, the alpha amylase enzyme may be derived from malt (sprouted barley), but in fuel-ethanol production, the enzyme is obtained solely as a bacterial product. The enzyme molecule contains a calcium atom which is essential for its activity.

American Society for Testing and Materials (A.S.T.M.).

Amyl Alcohol.
The principal constituent of fusel oil. Otherwise known as pentanol. Chemical formula C5H11OH. Eight isomers exist, the commonest being primary iso-amyl alcohol.

The name given to any enzyme which hydrolyzes (or breaks down) amylose, which is a major component of starch.



A major component of starch (together with amylopectin). The amylose molecule is composed of straight chains of hundreds of glucose units. In the grain-mashing process for ethanol production, amylose may first be broken down into short-chain dextrins by alpha amylase, which are, in turn, broken down into single glucose units by amyloglucosidase.


Anaerobic Digestion.

Ångstrom (Å).
A unit of length equal to one ten-billionth of a meter, used for measuring the diameter of chemical molecules. Thus, in ethanol dehydration, a molecular sieve material with holes 3 Ångstrom units in diameter, may be used to separate water, which has a 2.5 Å diameter, from ethanol which has a 4.5 Å diameter.


A chemical substance produced by micro-organisms, that has the capacity to inhibit the growth of other micro-organisms, or to destroy them. The antibiotic most commonly used in ethanol production is penicillin.

Antifoam (or Defoamer).

Antiscalant (or Scale Inhibitor).

Aquavit / Akvavit. (Various spellings.)
A name applied to various types of distilled spirits in northern Europe. In Germany it may apply to grape brandy. In Denmark it may apply to grain spirits flavored with caraway. In Sweden it may apply to grain spirits flavored with aniseed and dill.

Aqueous Solution.



Archer Daniels Midland (A.D.M.).

Armagnac, or Armagnac (Grape) Brandy.
A brandy distilled in the Gers Département (county) in south-western France. The département is precisely divided into three regions, Bas-Armagnac, Haut-Armagnac, and Tenarèze, and these names may be used to further designate the armagnac product. Armagnac is normally produced in a single pot-still distillation of wine and is then aged in oak barrels.

Arrack / Arak. (Various spellings.)

The suffix used to denote an enzyme. For example, the enzyme which breaks down amylose is referred to as an amylase.


Atomic Weight.

The term used to describe a constant-boiling mixture. It is a mixture of two (or more) components which has a lower boiling point than either (or any) component alone. For example, water, which boils at 100C, and anhydrous ethanol, which boils at 78.5C form a constant-boiling-mixture, or azeotrope, at 78.15C. The vapor of the mixture has the same composition as the liquid, and therefore, no further concentration can be achieved by normal distillation. Under normal pressures, it contains approximately 97 per cent by volume ethanol (194 proof). It is very expensive in energy to attempt to reach 194 proof, so 190 proof is generally considered to be the practical, economic azeotrope limit for fuel-ethanol distillation.

Azeotropic Distillation.

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- B -


Bacteria (Singular: Bacterium).
Any of a large group of microscopic plants constituting the class Schizomycetaceae, having round, rod-like, spiral, or filamentous single-celled bodies that are often aggregated into colonies, are often motile by means of flagella, and reproduce by fission or by the formation of asexual resting spores. They may live in soil, water, organic matter, or the live bodies of plants and animals. In ethanol production, bacteria are significant in that they compete with yeast to ferment the available sugars in a mash to products other than ethanol, and cause losses in yield. However, some bacterial cultures may be added deliberately to rum fermentations, to help produce certain desired congeners. One genus of bacteria, Zymomonas is currently being examined commercially, for its ability to ferment sugars to ethanol.

Bacterial Contamination.

Balling (or Brix).
A scale used to measure the specific gravity of a liquid in relation to that of a solution of sugar in water. Each unit on the scale is equivalent to one percent by weight of sugar. Thus a mash of 20 balling has the same specific gravity as a 20 per cent w/w sugar solution. The scale is frequently considered to indicate the percentage of dissolved solids in a liquid, although this is only true of solutions of pure sugar. Traditionally, the term "Balling" has been used in grain distilleries, while "Brix" has been used in sugar mills and rum or molasses-alcohol distilleries. The measurement is accomplished by use of a Balling (or Brix) hydrometer.

Barbet Time.


A liquid measure equal to 42 U.S. gallons, or 5.6 cubic feet. Or, a wooden container used for the aging and maturation of alcoholic beverages. Barrels used for whiskey maturation are made of oak wood, and have a capacity of about 52 U.S. gallons. Barrels may be used only once for aging bourbon whiskey, so there is a worldwide trade in used bourbon barrels for aging other alcoholic products such as Scotch whisky and rum.

Base Losses.

Batch Cooking.

Batch Distillation.

Batch Fermentation.
The fermentation of a set amount of mash in a single vessel, in a discontinuous operation. In the ethanol-production industries, batch fermentation predominates over continuous fermentation.



Beer Preheater.

Beer Still.
The distillation unit used for the initial removal of ethanol from finished beer. It generally consists of a stripping section which extracts the ethanol from the beer and a concentrating or rectifying section, which normally takes the ethanol up to 190 proof (95G.L.). Beer stills may consist of a single tall column, or two or more columns standing side by side, linked by vapor pipes.

Beer-Stripping Column.

Beer Well.


Beta Amylase.
An enzyme which hydrolyses the long-chain amylose molecules in starch into fermentable maltose, the dimer (or double-molecule) of glucose. (It is an exo-enzyme in that it works from an outer end of the molecular chain, breaking off maltose molecules one by one.) It is found in malt (sprouted barley), in association with alpha amylase. With the advent of microbial amyloglucosidase enzymes, malt amylases are generally only used in the production of heavily-flavored beverage alcohol.

Beta Glucan.

Beta Glucanase.

Beverage Alcohol.

Binary Azeotrope.
An azeotrope or constant boiling mixture having two components, such as ethanol and water.



Biological Oxygen Demand (B.O.D.).



Blended Whisky.
Defined by the B.A.T.F. as a mixture which contains straight whisky, or a blend of straight whiskies, at not less than 20 per cent on a proof-gallon basis, excluding alcohol derived from added harmless coloring, flavoring or blending materials, and, separately, or in combination, whisky or neutral spirits. A blended whisky containing not less than 51 per cent on a proof-gallon basis of one of the (recognized) types of straight whisky, may be further designated by that specific type of straight whisky; e.g. "Blended rye whisky."

Blender Tax Credit.


Boiler Efficiency.

Boiling Point.

The term used to refer to the herbs, spices and other plant materials used in the production of gin. By definition, gin botanicals must include juniper berries and may include materials such as orange and lemon peels, iris (orris) root, coriander seed, fennel seed, angelica root, caraway see, cinnamon bark, cassia bark, cardamom seed, etc.

Bourbon Whisky.


British Thermal Unit (B.T.U.).
The amount of heat required to raise the temperature of one pound of water one degree Fahrenheit, under defined pressure conditions. It is the standard unit for measuring heat energy in the U.S.




Bubble Cap.
A contacting device used on some distillation plates. It consists of a cylindrical "chimney", set in a hole in the plate, covered by a dome-shaped cap, which deflects the vapors rising up the chimney, to cause them to pass through the liquid layer on the plate.

Bureau of Alcohol, Tobacco and Firearms (B.A.T.F.).
An agency of the Department of the Treasury entrusted with enforcing laws covering the production, distribution and use of alcohol, tobacco and firearms.


Butanol (Butyl Alcohol).
A minor constituent of fusel oil. Chemical formula C4H9OH. Four isomers exist. They are all colorless, toxic flammable liquids. n-Butanol may be produced as a co-product with acetone and ethanol by the fermentation of selected carbohydrates with the anaerobic bacterium Clostridium acetobutylicum. Butanols are used as solvents and chemical intermediates.


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- C -

An apple brandy produced in Normandy, France, by the distillation of a fermented mash of apples. It is subjected to two pot-still distillations, and is then aged in oak barrels.

Canadian Whisky.


Carbon Dioxide.
A colorless non-flammable gas. Composition CO2. It does not support human respiration, and in high concentrations it causes asphyxiation. It is approximately 1.5 times the weight of air, and tends to accumulate in floor drains, pits and in the bottoms of unventilated tanks. It is produced by various means, notably the combustion of fuels in an excess of air, and is a byproduct of yeast fermentation. It may be recovered from fermentations and compressed to a liquid or solid ("dry-ice").

Carbon Monoxide.

Carbon Steel.

Caribbean Basin Initiative (C.B.I.).

A root crop with a high starch content, grown in the tropics and sub-tropical regions. Known in Brazil as "manioc", it is used there as an alternative to sugar cane, as a feedstock for ethanol production. It is also processed for food as "tapioca."




Cell Recycle.

An enzyme capable of hydrolyzing long-chain cellulose molecules into simple sugars, or into short-chain polymers.


Celsius (or Centigrade).
A temperature scale in which (at normal atmospheric pressure), water freezes at zero degrees and boils at 100 degrees.

Centrifugal Pump.


Chemical Oxygen Demand (C.O.D.)

Chlorine Dioxide.
Chemical formula ClO2. It is a strongly-oxidizing, yellow-to-reddish-yellow gas at room temperatures. It has an unpleasant odor, similar to that of chlorine, and reminiscent of that of nitric acid. It is unstable in light. It reacts violently with organic materials and is easily detonated by sunlight or heat, in concentrations greater than 10 per cent at atmospheric pressure. Boils at 11C and freezes at -59C. Chlorine dioxide may be used as a sterilant, and may be produced in situ for sterilizing yeast mashes, by addition of sodium chlorite solution in the presence of acids or chlorine (or hypochlorite solution). It is considerably more effective as a sterilant than straight chlorine.


C.i.p. System.

Citrus Molasses.
A by-product of the citrus juice industry. Citrus residue, mainly peel, is treated with lime, and then passed through a press. The press liquor is then evaporated to a viscous, dark-brown molasses, of about 72 Brix. Citrus molasses is similar to cane blackstrap molasses, having about 45 per cent total sugars. However, it has more protein and a much lower ash content than blackstrap. Citrus molasses may be diluted and fermented for ethanol production, but it may need pretreatment to reduce the content of d-Limonene, (commonly referred to as "citrus-stripper oil") which tends to inhibit yeast growth.

Cleaning-in-place System (C.i.p.).

Closed Receiver.


Coccus (Plural = Cocci).
A type of bacteria whose cells are spherical in form. They may occur as single cells, clusters or long chains.


Cognac or Cognac (Grape) Brandy.


Co-Mingled Tank.
The term used for fuel-ethanol tanks at refineries or pipeline terminals, where two or more suppliers may share the same tank for storing their ethanol. (This necessitates the tank owner or operator establishing quality standards for product put into the tank.)

Commodity Credit Corporation (C.C.C.).

Completely-Denatured Alcohol (C.D.A).
A term used by the B.A.T.F. to describe ethanol which has been made unfit for human consumption by addition of specified denaturants such as methyl-isobutyl-ketone, kerosene or gasoline.

Concentrating Column.


Condensed Molasses Solubles (C.M.S.).
The term used to describe molasses stillage which has been concentrated by evaporation. The molasses residue (after fermentation and distillation, may be concentrated to about 60 Brix (or approximately 60 per cent solids), to be sold for use as a substitute for molasses in animal feeds. Its principal use in feeds is as a caking agent and dust suppressant. It contains a high concentration of salts.


Chemical compounds which are produced together with ethanol in the fermentation process. They are frequently referred to as "impurities". Common congeners are methanol, acetaldehyde, esters (such as ethyl acetate), and fusel oils, (higher alcohols, particularly amyl alcohols.) Fermentation conditions may be adjusted to control congener formation, depending on the requirements for the end product.

Constant-Boiling Mixture.

Continuous Cooker.
A system into which a mash of water, grain and enzymes may be fed continuously, to be cooked and discharged to the fermentation system. Continuous cookers generally consist of a slurry tank connected by a pump to a steam-jet heater, a holding vessel or lengths of piping (to provide some residence time at the cooking temperature), one or more flash vessels (to cool the cooked mash) a holding vessel for enzymic liquefaction, and a heat exchanger for final mash cooling. Continuous cookers are more common in fuel-ethanol plants than in beverage-alcohol plants.

Continuous Distillation.

Continuous Fermentation.

Control Loop.



Cooling tower.


A place where wooden barrels are made or repaired. Also used to refer to a supply of barrels (i.e. the product of the work of a cooper).



Corn-Steep Liquor.

Corn Whisky.
Defined by the B.A.T.F. as "whisky produced at under 160 proof, from a fermented mash containing not less than 80 per cent corn grain". If corn whisky is stored in oak barrels, the B.A.T.F. stipulates that the proof should not be more than 125, and that the barrels be used, or uncharred, if new. Furthermore, the whisky cannot be subjected to any treatment with charred wood.


Corrosion Inhibitor.


Country Liquor.

Crude-Oil-Windfall-Profits Tax Act of 1980.

A colorless, flammable, alicyclic hydrocarbon liquid, of chemical formula C6H12, which boils at 80.3C, and freezes at 6.5C. It is used as an alternative to benzene as an entrainer in the dehydration of ethanol by azeotropic distillation.

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- D -





Dealer Tank Wagon (D.T.W.).

Vessel used for the separation of two-phase liquids. In a fusel-oil decanter, an upper fusel-oil phase is separated from a lower aqueous-ethanol phase. In a benzene-column reflux decanter, the upper, mainly-benzene phase is separated from the lower, mainly-water phase. See Phase Separation.

Deficit-Reduction Act of 1984.


The process of removing water from a substance, particularly the removal of most of the remaining 5 per cent of water from 190 proof ethanol, in the production of absolute or anhydrous ethanol.

Demethylizing column.

A substance added to ethanol to make it unfit for human consumption, so that it is not subject to taxation as beverage-alcohol. The B.A.T.F. permits the use of 2 - 5 per cent of unleaded gasoline (or similar, specified substances) for use as denaturants for fuel ethanol. (See also specially-denatured alcohol and completely-denatured alcohol.)

Denatured Alcohol.

Department of Energy. (D.o.E.).



Detergent Package.


A non-fermentable, large, branched-chain polymer of sucrose molecules, produced in molasses by bacterial contamination (mainly Leuconostoc mesenteroides). It gives a "ropey" appearance to molasses when stirred or poured, and reduces ethanol yield on fermentation.



Dextrose Equivalent (D.E.).
A measure of the degree of hydrolysis or saccharification of starch. It is no longer considered as significant as previously in ethanol production, with the more general acceptance of simultaneous saccharification and fermentation.

Di-Ethyl Ether.

Differential-Pressure Cell (D.P. Cell).


A compound sugar which yields two monosaccharide units on hydrolysis. For example, lactose yields glucose and galactose, sucrose yields glucose and fructose, while maltose yields two glucose units.

Disc-and-Donut Column.




Distilled Spirits.

Distilled-Spirits Permit (D.S.P.).

Distillers Bushel.
56 lbs of any grain, regardless of volume.

Distillers Dried Grain (D.D.G.).
The dried residual by-product of a grain-fermentation process. It is high in protein, as most of the grain starch has been removed. It is used as an animal-feed ingredient. By strict definition, D.D.G. is produced only from the solids separated from whole stillage by centrifuging or screening. In practice, the term is commonly used to describe the entire dried-stillage residue, making it synonymous with D.D.G.S.

Distillers Dried Grain with Solubles (D.D.G.S.).

Distillers Dried Solubles.

Distillers Feeds.

Distillers Feeds Research Council.
An organization established in the U.S. in 1945, to fund and coordinate university research into the utilization of D.D.G. It holds an annual conference in early April to publicize its findings. It was previously a division of the Distilled Spirits Council of the U.S., which is a beverage-alcohol-producers organization. It is now an independent body with membership open to all alcohol producers. Its headquarters are in Des Moines, IA.

Distillers Wet Grain (D.W.G.).


Distillery-run Barrels.
Recently-emptied, used whiskey barrels which have not been sorted to remove those with or without defects.

DMA 67Y.

Downcomer (or Downpipe).

D.P. Cell.

Dried-Fruit Brandy.

Dry Degermination.
A process for the removal of germ from grain without the need for steeping and wet milling. It may involve some pretreatment of the grain to raise the moisture content before processing. It is used in Scotland for corn milling in grain-whisky plants, and is used in the production of corn flakes, but is not commonly used in the U.S. ethanol- production industry.

Dry Milling.



Dual-Flow Plate (or Tray).

A Caribbean synonym for vinasse or molasses stillage. It is commonly used to refer to vinasse which has been stored for some time, to allow bacterial development, prior to being used as backset, in the production of heavily-flavored rums.

Dupont Waiver.


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- E -

Eau de vie (Plural: Eaux de Vie).




An enzyme which acts on internal portions of a large polymeric molecule rather than around the periphery. For example, the alpha amylase enzyme hydrolyses linkages within amylose and amylopectin molecules, as an endo-enzyme. In contrast amyloglucosidase acts as an exo-enzyme in only hydrolyzing the outermost linkages.

Energy-Investment-Tax Credit (E.I.T.C.).

Energy-Policy Act of 1992.

Energy-Security Act of 1980.

Energy-Tax Act of 1978.
U.S. federal legislation which instituted the first excise-tax exemption for gasoline blended with 10 per cent fermentation ethanol. It exempted the blends from the entire tax of 4 cents per gallon. It also created an energy-investment-tax credit (E.I.T.C.) of 10 per cent, which applied to equipment for converting biomass to ethanol, in addition to the standard 10 per cent investment-tax credit.


Environmental Protection Agency (E.P.A.).

Enzymatic Hydrolysis.
The hydrolysis of a polymer by the use of enzymes. In the case of starch hydrolysis, an alpha amylase enzyme may be used in the initial hydrolysis to achieve liquefaction, and an amyloglucosidase enzyme may be used to complete the hydrolytic saccharification to fermentable sugars.





Otherwise known as ethyl alcohol, "alcohol", "grain-spirit", or "neutral spirit", etc. A clear, colorless, flammable oxygenated hydrocarbon. Chemical formula: C2H5OH. It has a boiling point of 78.5C in the anhydrous state. However, it forms a binary azeotrope with water, with a boiling point of 78.15C at a composition of 95.57 per cent by weight ethanol.


Ethyl Acetate.

Ethyl Alcohol.

Ethyl Carbamate.

Ethylene Glycol.

Ethyl Tertiary-Butyl Ether.



Excise-Tax Exemption.


Extractive Distillation.
A process in which a substance referred to as an extractant is added to a mixture being distilled, to change the volatility of one or more components. The less-volatile mixture will then descend in a continuous-distillation column, while the more volatile components may be removed in the condensed overhead vapors. In the use of extractive distillation in the dehydration of ethanol, liquid extractants such as ethylene glycol, or glycerol may be used. Salts such as potassium and sodium acetates may also be used alone in molten form, or in mixtures with glycerol etc. Anhydrous ethanol is recovered in the overhead condensate, while the water combines with the extractant to emerge from the bottom of the column. (This is the reverse of the situation in azeotropic distillation, as with benzene, etc.) The extractant is then separated from the water in another column (or an evaporator) and is recycled.

In the production of neutral spirit, light rums or whiskies, extractive distillation may be used to remove fusel oils and some other congeners in the condensed overhead vapors. In this instance, the extractant is water, as some of the congeners which have a lower volatility than ethanol in a concentrated state, may have a higher volatility than ethanol when diluted with water, so that they rise up the extractive distillation column, while the ethanol descends.


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- F -

Facultative Anaerobe.
Term used to describe a microorganism such as a yeast, which is essentially aerobic (or air-requiring), but can also thrive under anaerobic (or air-free) conditions.

Fahrenheit Scale.
A temperature scale in which the boiling point of water is 212F and the freezing point is 32F. (The zero point was originally established as the lowest point obtainable with a mixture of equal weights of snow and common salt.)

Farmers Home Administration (FmHA).

Federal Excise-Tax Exemption.

Feed Plate (or Feed Tray).
The plate or tray onto which the distilland (liquid to be distilled) is introduced in a distillation column. In theory, it is the point in a column above which enrichment or concentration occurs, and below which stripping occurs.


Fermentable Sugars.


Fermentation Efficiency.
The measure of the actual output of a fermentation product such as ethanol, in relation to the theoretically-obtainable yield.

Fermentation Ethanol.

The vessel in which the process of mash fermentation takes place. The vessel may be fabricated from steel, fiberglass, etc., and is normally fitted with an internal or external cooling system for controlling the temperature of the fermenting mash.


Flame Arrester.

Flash Cooling.

Flash Point.

Flavored Distilled Spirits.

Flexible-Fueled Vehicle (F.F.V.).


Floc de Gascogne.



Fluidized-Bed-Combustion Boiler.

Fossil Fuel.

Fractional Distillation.
A process of separating mixtures such as ethanol and water, by boiling and drawing off the condensed vapors from different levels of the distillation column.

Fructose (or Levulose).
A fermentable monosaccharide, or simple, single-unit sugar, of the chemical formula C6H12O6. Its chemical structure is similar to that of glucose, but it has the distinction of being sweeter to the taste. It may be produced from glucose by enzymatic isomerization, as in the production of high-fructose corn syrup (HFCS).

Fruit Brandy.

Fuel-Grade Ethanol.

Fuel Ethanol.
Usually denotes anhydrous ethanol or motor-fuel-grade ethanol which has been denatured by addition of 2 - 5 per cent unleaded gasoline, and which is intended for use as an automotive fuel in blends with gasoline.


Fusel Oil.
Term used to describe the higher alcohols, generally the various forms of propanol, butanol and amyl alcohol, which are congeners, or by-products of ethanol fermentation. Normally, predominantly iso-amyl alcohol. Their presence in alcoholic beverages is known to be a cause of headaches and hangovers. The fusel oils have higher boiling points than ethanol and are generally removed in the distillation process, to avoid accumulations in the rectifier. They may be subsequently added back into the anhydrous product for motor-fuel-grade ethanol.

Fusel-Oil Decanter.

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- G -

A monosaccharide, of chemical formula C6H12O6, which, with glucose, is a constituent of the disaccharide lactose. It is an isomer of glucose, but is less-readily fermented by yeasts to ethanol.


Gas Chromatography (G.C.).

Gas-Liquid Chromatography.

Gasohol (or Gasahol).
A trade name registered in Nebraska in 1973, by the Nebraska Agricultural Products Industrial Utilization Committee, which was later renamed the Nebraska Gasohol Committee. (The committee was responsible for laying the groundwork for the development of the present-day U.S. fuel-ethanol industry.) The trade name, in either spelling, covers a blend of anhydrous ethanol "derived from agricultural products" with gasoline (not necessarily unleaded). The committee has freely granted permission for commercial use of the trade name, provided it is not used for blends containing alcohols other than ethanol.


Gasoline Extender.

Gay Lussac (G.L.).
The name given to a scale of the concentration of ethanol in mixtures with water, where each degree is equal to 1 per cent by volume (i.e. 1 G.L. is equivalent to 2 U.S. proof.) It takes the name from the French chemistry pioneer, Joseph-Louis Gay Lussac. The scale is used extensively in Europe, South America etc.

Gay Lussac Equation.


Gear pump.

In reference to the cooking of starchy feedstocks, gelatinization is the stage in which the starch granules absorb water and lose their individual crystalline structure to become a viscous liquid gel. Gelatinization is significant in that it is the preliminary process necessary to render starch susceptible to enzymatic hydrolysis, for conversion to fermentable sugars.

Geneva Gin.




An enzyme which hydrolyses starch into its constituent glucose units. (See Amyloglucosidase.)


An enzyme which hydrolyses glucan. (See Beta Glucanase.)


Glucose Isomerase.


Glycerol (or Glycerine).
A clear, colorless, viscous, sweet-tasting liquid belonging to the alcohol family of organic compounds. It has a chemical formula of CH2OHCHOHCH2OH, having three hydroxyl (OH) groups. It is a by-product of alcoholic fermentations of sugars. It is hygroscopic, and may be used as an extractant in the dehydration of ethanol.

Grain Alcohol.

Grain Spirit.

Grain Whisky.

Grain Sorghum.
(Otherwise known as "milo"), a sorghum grown for grain production, as distinct from sweet sorghum grown for the sugar content of its stem. It may be used as a feedstock for ethanol production.

Gram Negative.

Gram Positive.

Gram Stain.

Grappa, or Grappa Brandy.

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- H -

Hammer Mill.

Term used to describe the impurities produced in ethanol fermentations ("congeners"), which have lower boiling points than ethanol. They include methanol and aldehydes.

Heads-concentrating column.
A distillation column used to concentrate heads removed in the production of neutral spirit, light rums and whiskies.

Heat Exchanger.

Heat of Condensation.

Heat of Vaporization.




Hiag Process.
A process developed in Germany in the 1930's for the dehydration of ethanol by extractive distillation, using a mixture of sodium and potassium acetates as the extractant.

High Boilers.

Higher Alcohols.
Alcohols having more than two carbon atoms within their molecule. They exist in various isomeric forms. As the number of carbon atoms increases, so also the number of isomers increases, but at a greater rate. The lower members of this group, namely propanol, butanol and amyl alcohol, are major constituents of fusel oil.

High-Fructose Corn Syrup (H.F.C.S.).

High-Performance Liquid Chromatography (H.P.L.C.).

High-Test Molasses (H.T.M.).

A wooden barrel with a capacity of approximately 66 U.S. gallons (250 liters), used in Scotland for aging whisky. It is usually constructed from shooked, bourbon-whiskey barrels, of 52 gallons capacity, by using additional staves and larger heads and hoops.

Holland's Gin or Geneva Gin.





A direct-reading instrument for indicating the density, specific gravity or other similar characteristics of liquids. It is generally comprised of a long-stemmed glass tube with a weighted bottom, which floats at different levels in liquids of different densities. The reading is taken at the meniscus, where the calibrated stem emerges from the liquid. The liquid temperature is normally determined when taking a reading, and reference is made to hydrometer tables to obtain a correction to a standard temperature. A proof hydrometer measures the content of ethanol in a mixture with water. A brix or balling hydrometer measures on a scale equivalent to the percentage of sugar by weight in an aqueous solution.

Hydroselection column.

Hydrous Ethanol.

Term used to describe a substance which has the property of absorbing moisture from the air. Anhydrous ethanol is hygroscopic, and its exposure to moist air should therefore be minimized.

Hydroxyl Group.

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- I -



Imperial Gallon.
A measure of volume in the British system, defined in 1824 as the volume occupied by 10 pounds weight of water at 62F and 30 inches of barometric pressure. It is the equivalent of 11/5 U.S. gallons, or 4.546 liters in the metric system.

Indian-Made Foreign Liquor (I.M.F.L.).

Industrial Alcohol.
Denotes any ethanol which may be intended for industrial uses, such as solvents, extractants, antifreezes and intermediates in the synthesis of innumerable organic chemicals. The term covers ethanol of both synthetic and fermentation origin, of a wide range of qualities and proofs, with or without various denaturants.

Industrial-Development Revenue Bonds (I.D.R.B.).

The portion of a culture of yeast (or bacteria) which is used to start a new culture or a fermentation.


An enzyme capable of hydrolyzing inulin to its component fructose units.


Irish Whiskey.

Iso-Amyl Alcohol.




Iso-Propyl Ether (I.P.E.).
An ether (otherwise known as di-iso-propyl ether), which is used in some fuel-ethanol plants as an entrainer in the dehydration process, as an alternative to benzene etc. It is a colorless, volatile liquid, chemical formula (CH3)2CHOCH(CH3)2, which boils at 67.5C and freezes at -60C. It readily forms explosive mixtures with air. Inhalation of vapors may cause narcosis and unconsciousness.

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Jet Cooker.
An apparatus for the continuous cooking of grain mashes, in which the mash is pumped past a jet of steam which instantly heats the mash, to gelatinize the starch.


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Karl Fischer Titration.
A method to chemically determine the amount of water present in a sample of ethanol and/or other substances. When correctly practiced, the method can give an extremely accurate measurement of very small quantities of water in ethanol (in parts per million), even if gasoline denaturant is present. See Titration.


Kjeldahl Method.

Kluyveromyces fragilis (or marxianus).
A lactose-fermenting yeast used in the production of ethanol from cheese whey.

Kubierschky Process.
The first patented process for the continuous dehydration of ethanol with benzene. With relatively minor variations, the process developed in 1914 on the basis of Young's earlier batch process, is still used in many fuel-ethanol plants.

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Lactic Acid.

A genus (or class) of bacteria which produce lactic acid as a major product in the fermentation of carbohydrates. They are found extensively in fermenting food products, such as souring milk and in grain dust. They are the principal cause of loss of yield in ethanol fermentations. Otherwise referred to as lactic-acid bacteria, they are generally gram-positive and controllable with penicillin and certain other antibiotics.


Lag Phase.
Applied to yeast propagation, refers to the initial period in which the yeast inoculum becomes adapted to the mash, prior to attaining the rapid increase in cell numbers referred to as the logarithmic phase.

Latent Heat.

Lead Phase-Out.


Lees Brandy.
Defined by the B.A.T.F. as brandy distilled from the lees of standard grape, citrus or other fruit wine. It is designated "lees brandy", and qualified by the type of fruit from which the lees were derived.


Light Whisky.




The change in the phase, or conversion of a solid substance to the liquid state. In reference to starch, it is the stage in the cooking and saccharification process, in which gelatinized starch is partially hydrolyzed by an alpha amylase enzyme (or occasionally by an acid) to give soluble dextrins. This converts the starch mash into a free-flowing liquid.

Liqueurs and Cordials.

Liter (or Litre).

Loan Guarantee.

Logarithmic Phase.
Applied to yeast propagation, refers to the period in which cell numbers are increasing at an exponential rate, after the initial lag phase.

Low Boilers.


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Barley grains which have been steeped in water and then allowed to germinate. The germination is normally halted by drying the grains when the sprouts are about the same length as the grains. At this stage, the malt (or "malted barley") contains considerable amounts of alpha and beta amylase enzymes, which can saccharify the barley starch and other additional starch in a mash, to yield fermentable sugars. (In Scotland, the drying may be done by exposing the malt to a flow of peat smoke. This imparts a smokey odor to the malt.) Malt is used in whisky production, mainly for its contribution to product flavor, while in fuel-ethanol production the necessary saccharifying enzymes are normally derived from microbial sources.

Malt Wine.

Malt Whisky.

In the U.S., it is defined by the B.A.T.F. as a whisky produced at less than 160 proof from a fermented mash containing at least 51 per cent malted barley, and stored at under 125 proof in charred, new, oak barrels. In Scotland, malt whiskies are made from a 100 per cent malted-barley mash, and may be aged in previously-used, oak barrels. Malt whiskies may be mixed with grain whiskies, to impart much of the characteristic flavor of blended Scotch whisky.





Marc Brandy.


A mixture of milled grain or other fermentable carbohydrate in water, which is used in the production of ethanol. The term may be used at any stage from the initial mixing of the feedstock in water, prior to any cooking and saccharification, through to the completion of fermentation, when it becomes referred to as "beer".


McCabe-Thiele Diagram.


Mechanical Vapor Recompression (M.V.R.).



Methane Digester (or Anaerobic Digester).

Methanol (or Methyl Alcohol).

A colorless poisonous liquid, with essentially no odor and very little taste. It is the simplest alcohol, and has a formula CH3OH. It boils at 64.7C. It is miscible with water and most organic liquids, including gasoline. It is extremely flammable, burning with a nearly invisible blue flame. It is a congeneric product of ethanol fermentations. Having a lower boiling point than ethanol, it tends to be a major component of the "heads" stream on distillation. Due to its miscibility with benzene, its presence in a hydrous ethanol feed may reduce the efficiency of dehydration processes where benzene is used as an entrainer. Methanol is produced commercially by the catalyzed reaction of hydrogen and carbon monoxide. It was formerly derived from the destructive distillation of wood, which caused it to be known as "wood alcohol". Methanol may be blended with gasoline, but requires a co-solvent such as ethanol or a higher alcohol to maintain it in solution. See Dupont Waiver. See Demethylizing Column.

Methyl Tertiary Butyl Ether (M.T.B.E.).

A colorless, flammable, liquid oxygenated hydrocarbon. Chemical formula (CH3)3COCH3.. It contains 18.15 per cent oxygen and has a boiling point of 55.2C. It is produced by reacting methanol with isobutylene. Its use as an octane enhancer in gasoline has been approved by the E.P.A., at levels of up to 15 per cent.



Milo (or Milo-Maize, or Millet, or Grain Sorghum).

Molar Solution.


The thick liquid remaining after sucrose has been removed from the mother liquor (of clarified concentrated cane or beet juice), in sugar manufacture. Blackstrap molasses is the syrup from which no more sugar may be removed economically. It has usually been subjected to at least three evaporating and centrifuging cycles to remove the crystalline sucrose. Its analysis varies considerably, depending on many factors, including sugar-mill equipment and operational efficiency, but it may contain approximately 45 - 60 per cent by weight of fermentable sugars and approximately 10 per cent ash (or salts). It is commonly used as an ethanol feedstock when prices are favorable. High-test molasses (H.T.M.) is not a true molasses, as it is the mother liquor from which no crystalline sugar has been removed by centrifugation, but which has been treated with acid to reduce crystallization. It may contain approximately 80 per cent by weight of sugars, and is very low in ash. It is normally only produced in years when the sugar price does not justify its recovery. It may be used as an ethanol feedstock when prices are favorable, and has the advantage over blackstrap of causing less distillation-column scaling due to ash. However, it requires more nutrients for fermentation. See also Citrus Molasses.



Molecular Sieve.

A microporous substance composed of materials such as crystalline alumino-silicates, chemically similar to clays, and belonging to a class known as zeolites. The size of the pores in the substance may vary with its chemical structure, being generally in the range of 3 to 10 Ångstrom (Å) units in diameter. With material having a very precise pore size, it is possible to separate smaller molecules from larger ones, by a sieving action. For example, in ethanol dehydration with a potassium alumino-silicate material prepared with pores of a diameter of 3Å units, water molecules with a diameter of 2.5Å may be retained by adsorption within the pores, while ethanol molecules of a diameter of 4Å cannot enter, and therefore flow around the material.

The term "molecular sieve" is frequently used loosely to describe the entire ethanol-dehydration apparatus which holds the beads of sieve material and includes the equipment and controls necessary to regenerate them when saturated with water.

Molecular Weight.




Mother Yeasting.

Motor-Fuel-Grade Ethanol (M.F.G.E.).

Motor Octane Number (M.O.N.).



Multiple-Effect Evaporator.

Municipal Solid Waste (M.S.W.).


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Nebraska Gasohol Committee.

A committee previously known as the Nebraska Agricultural-Products-Utilization Committee. Starting in 1973, it was responsible for initiating trials on the use of ethanol-gasoline blends, which led to the development of a nationwide fuel-ethanol industry. It is the registered owner of the trade name "Gasohol" or "Gasahol".

Net Energy Balance.

Neutral Brandy.

Neutral spirit.

Defined by the B.A.T.F. as "distilled spirits produced from any material at or above 190 proof". In practice, neutral spirit is purified, odorless, tasteless and colorless ethanol, which has been produced by distillation and rectification techniques which remove any significant amount of congeners. It is used in the production of beverages such as vodka, gin, cordials, and cream liqueurs.

Nitrogen Oxides.

Normal Solution.


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Occupational-Safety and Health Administration (O.S.H.A.).


Octane Enhancer.

Octane Rating (or Octane Number).


Office of Alcohol Fuels.

A division of the U.S. Department of Energy charged with a wide range of activities to promote the development of the production and use of alcohol fuels. It was established by the Energy-Security Act of 1980.

Oil Price Information Service (O.P.I.S.).



Short-chain polymers of simple sugars (or monosaccharides), generally considered to cover the range of 2 to 8 units. Short dextrins produced by hydrolysis of starch are included in this category.

Omnibus Reconciliation Act of 1990.



Organoleptic Testing.

The quality-control process of checking samples of alcoholic products on the basis of odor and taste. It is normally performed by comparing samples of new production with older samples of acceptable quality, which have been designated for use as "standards".

Orifice Meter.



An aniseed-flavored distilled spirit, produced in Greece, Cyprus and other Middle-East countries.

Overhead Vapors.

Oxygenated Fuels.

Literally meaning any fuel substance containing oxygen, the term is commonly taken to cover gasoline-based fuels containing such oxygen-bearing compounds as ethanol, methanol, M.T.B.E., E.T.B.E., etc. Oxygenated fuel tends to give a more complete combustion of its carbon to carbon dioxide (rather than monoxide), to reduce air pollution from exhaust emissions.

Oxygenated Fuels Association (O.F.A.).

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Packed Distillation Column.


Abbreviation for Petroleum Administration for Defense District.




The collective name for salts of a series of antibiotic organic acids produced by a number of Penicillium and Aspergillus species molds, active against most gram-positive bacteria and some gram-negative cocci. (See Gram stain.) The commonest type of penicillin used in ethanol fermentations to control bacterial contamination is the potassium G form, otherwise known as benzyl penicillin potassium.




Permanganate (or Barbet) Time.

A laboratory test used for assessing the quality of samples of industrial or beverage alcohol. It is the time required for an alcohol sample to decolorize a standard potassium permanganate solution. The time is an indication of the reducing (deoxidizing) power of the sample, and is considered to be a crude measure of the presence of congeners.


Petroleum Administration for Defense District (P.A.D.D.).



Phase Separation.

Pineau des Charentes.


A type of brandy distilled from the wine of muscat grapes, in South American countries, particularly Peru.

Plate (or Tray).

A contacting device placed horizontally at intervals within a distillation column. Plates may be simple perforated discs, with or without downcomers, as in the sieve plate and the dual-flow plate, or they may have bubble caps, tunnel caps, or various types of floating valves, to improve the contact between the rising vapor and descending liquid. Sieve plates and tunnel caps are the most common form of plates used in ethanol production facilities.

Plate (or Trayed) Distillation Column.




Pomace Brandy or Marc Brandy.

Defined by the B.A.T.F. as brandy distilled from the (fermented) skins and pulp of sound, ripe grapes, citrus or other fruit, after the withdrawal of the juice or wine therefrom. it is designated "pomace brandy", or "marc brandy", and qualified by the name of the fruit from which it is derived. Grape pomace brandy may be designated as "grappa" or "grappa brandy."

Positive-Displacement Pump.

Potassium Alumino-Silicate.


A simple batch distillation unit used for the production of heavily-flavored distillates for beverage use. It consists of a tank, (which is heated either by an internal steam coil, or by an external fire), and an overhead-vapor pipe leading to a condenser. It may be used in the production of heavily-flavored rums and whiskies.



A measure of the absolute-ethanol content of a distillate containing ethanol and water. In the U.S. system, each degree of proof is equal to 0.5 per cent of ethanol by volume, so that absolute ethanol is 200 proof. In the Imperial system "proof", (or 100 proof), is equal to 57.06 per cent ethanol by volume, or 48.24 per cent by weight, while absolute ethanol is 75.25 over proof, or 175.25 proof.

Proof Gallon (p.g.).

Proof Tables.


Propanol (or Propyl Alcohol).

A minor constituent of fusel oil. Chemical formula C3H7OH. It exists as either of two isomers. Both are colorless, toxic, flammable liquids, with odors similar to that of ethanol.




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Rack Price.


A name given in Turkey to a product similar to Ouzo.


A device for supplying heat to a distillation column without introducing live steam. It generally consists of a shell-and-tube heat exchanger connected to the base of the column, with liquid from the column entering inside the tubes, to be heated indirectly by steam on the shell side.


Recoopered barrels.


Rectified Spirit.

A distilled spirit which has undergone some degree of rectification.

Rectifying Column (rectifier, rectification column, or rectifying section).


Reflux Ratio.

The ratio of the amount of condensate being refluxed to the amount being withdrawn as product. Generally, the higher the reflux ratio, the greater is the degree of separation of the components in a distillation system.

Renewable Fuels Association (R.F.A.).

Research Octane Number (R.O.N.).

Reverse Osmosis (R.O.).




Roller Mill.

A mill for crushing or grinding grain or other solid material by passing it between two steel rollers. The rollers may be smooth, or serrated to shear the grain, and they may turn at differing speeds to increase the abrasion. Roller mills are suitable for small grains such as wheat, but do not perform as well as a hammer mill on corn.



Reid vapor pressure (R.v.p.).


Defined by the B.A.T.F. as "an alcoholic distillate from the fermented juice of sugar cane, sugar-cane syrup, sugar-cane molasses, or other sugar-cane byproducts, produced at less than 190 proof, in such a manner that the distillate possesses the taste, aroma and characteristics generally attributed to rum." Unlike the specifications for whiskies, the B.A.T.F. does not require that the rum be aged in oak barrels. British regulations specify that rum be produced "from sugar-cane products in sugar-cane-growing countries."


Rye-Malt Whisky.

Rye Whisky.

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The process of converting a complex carbohydrate, such as starch or cellulose, into fermentable sugars such as glucose or maltose. It is essentially a hydrolysis. The process may be accomplished by the use of enzymes or acids.

Sacc' Tank (or Saccharification Tank).



Scale Inhibitor.


Scotch Whisky.





A distilled spirit made in Japan, using rice as the fermentation feedstock.

Shooked Barrel (or Shook).

A used bourbon-whiskey barrel which as been dismantled to reduce the space requirements for transportation.

Sieve analysis.

A laboratory test made on grain meal, to check that the milling process is being conducted correctly. The meal is added to the top of a stack of sieves with increasingly-finer meshes descending downwards. The sieve stack is vibrated for a standard time period, and the weight percentage retained on each screen is determined. With hammermills, the sieve analysis will generally show that the meal gradually becomes coarser, as the hammers wear and need turning or replacement.

Sieve Plate (or Sieve Tray).

Simultaneous Saccharification and Fermentation (S.S.F.).

A procedure in which the saccharification of a cooked starch mash occurs in the fermenter (by addition of enzymes), simultaneously with the commencement of fermentation (by addition of yeast). This procedure is replacing the traditional process taken from the whiskey industry, in which there is a specific holding stage for saccharification with malt or microbial enzymes (in a sacc' tank), prior to the mash going to a fermenter.

Slurrying Tank.

Small Business Administration (S.B.A.).




Specially-Denatured Alcohol (S.D.A.).

The term is used to describe ethanol denatured with any formulation of compounds selected from a list approved by the B.A.T.F. The denaturant renders the ethanol unfit for beverage purposes, without impairing its usefulness for other applications.

Specific Gravity (S.G.).

Spent-Sulfite Liquor (S.S.L.).

Spirit Whisky.


Abbreviation for simultaneous saccharification and fermentation.



A mixture of two carbohydrate polymers (amylose and amylopectin), both of which are composed of glucose monomers linked together by glycosidic bonds. Starch is the principal energy-storage product of photosynthesis, and is found in most plants, particularly in roots, tubers and cereal grains. Starch may be subjected to hydrolysis (saccharification) to yield dextrins and glucose.



The mixture of non-fermentable (or non-fermented) solids and water, which is the residue after removal of ethanol from a fermented beer by distillation. Stillage may be dried to recover the solid material, (as D.D.G., in the case of grain feedstocks).

Stoichiometric Yield.



Straight Whisky.

Stripping Column (or Stripping Section).

The portion of a distillation column below the feed tray, in which the descending liquid is progressively depleted of its volatile components, by the introduction of heat at the base.

Sub-Octane Blending.



Any of a class of water-soluble, simpler-carbohydrate, crystalline compounds that vary widely in sweetness and include the monosaccharides and lower oligosaccharides. They may be chemically reducing or non-reducing compounds and are typically optically active. Examples include the monosaccharides, glucose, fructose, mannose and xylose, the disaccharides sucrose, maltose, lactose and the trisaccharides raffinose and maltotriose.

Sulfite Alcohol.

Sulfite-Waste Liquor (S.W.L.).

An effluent produced in the sulfite-pulping process used in some papermills. It partly consists of a dilute solution of sugars produced by the acid hydrolysis of cellulose. It may be used as a feedstock for the production of ethanol by fermentation, using selected yeast strains, after stripping out the sulfite (or sulfur dioxide) with steam.

Supplementary Column.

Surface Transportation and Uniform Relocation Assistance Act of 1987.

Surface-Transportation-Assistance Act of 1982.


Synthetic Ethanol.

Ethanol produced by any one of several synthetic processes, such as the catalytic hydration of ethylene, the sulfuric-acid hydration of ethylene, and the Fischer-Tropsch process, in which it is a major byproduct of the synthesis of methanol by catalytically reacting carbon dioxide and hydrogen. Synthetic ethanol is chemically identical to fermentation ethanol, but does not qualify for U.S. federal or state incentives for blending with gasoline, and may not be used in the production of alcoholic beverages.

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An unaged, Caribbean or South American alcoholic beverage produced by batch distillation of beers obtained by the fermentation of sugar-cane juice or molasses. It is similar to aguardiente and rum.



Technical Alcohol.


Ternary Azeotrope.

An azeotrope or constant-boiling mixture made up of three components. For example, a mixture of 74 per cent volume benzene, 18.5 per cent ethanol and 7.5 per cent of water forms an azeotrope boiling at 64.9C.


Tetra-Ethyl Lead (or Lead Tetra-Ethyl).

Theoretical Plate (or Tray).

Theoretical Yield.

Thermal Efficiency.

Thermal Vapor Recompression.


Thin Stillage.

The liquid portion of stillage which has been separated from the solids by screening or centrifuging. It contains suspended fine particles and dissolved material. It is normally sent to an evaporator, to be concentrated to a thick syrup which is then dried with the solids portion to give D.D.G.S.



Total sugars as invert (T.S.A.I.).

A simple crude analytical measure of reducing sugars in molasses.





Tunnel Cap.

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A process for the separation of colloidal or very fine solid materials, or large dissolved molecules, by filtration through microporous or semi-permeable membranes. The process may be used for removal of protein from cheese whey prior to fermentation.

United States Department of Agriculture (U.S.D.A.).



U.S. Gallon.

A measure of 231 cubic inches liquid at 60F. It is the equivalent of 3.785 liters, in the metric system, or 5/6 of an Imperial gallon.

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Vacuum Distillation.

Vacuum Fermentation.

A process of operating a fermentation under vacuum, so that the ethanol or other product is vaporized and removed as it is formed, to avoid its concentration becoming inhibitory to the yeast. In a patented variation known as the "Vacuferm" process, instead of maintaining the entire fermenter under vacuum, the fermenting beer is circulated through a vacuum chamber to flash off the ethanol, before returning the beer to the fermenter.


Vaporization (or Volatilization).

Vapor Pressure.

Vent Condenser.


The term sometimes applied to the stillage of molasses, grape juice, or other liquid ethanol feedstocks.




The tendency of a solid or liquid to pass into the vapor state at a given temperature. With automotive fuels, the volatility is determined by measuring the Reid vapor pressure (R.v.p.).


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A British synonym for distillers beer.

Wet Milling.


The condition when droplets of liquid fall through the holes of a sieve plate in a distillation column. It may be caused by (a) having a steam flow that is too low, or (b) having too low a liquid flow to maintain a level on the plate, or (c) having a tilted plate, so that the liquid depth is uneven.

Wheat Whisky


Whisky / Whiskey.

Defined by the B.A.T.F. as "an alcoholic distillate from a mash of grain, produced at less than 190 proof, in such as manner that the distillate possesses the taste, aroma and characteristics generally attributed to whisky". With the exception of corn whisky, it should be stored in oak barrels. (The B.A.T.F. uses the spelling "whisky", but the spelling "whiskey" is frequently used in the U.S. and Ireland.)

Whole Stillage.


Wine Gallon.

A U.S. gallon of liquid measure, as distinct from a proof gallon.

Wood Alcohol.


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A pentose (or 5-carbon sugar), derived from the hydrolysis of hemicellulose. Chemical formula C5H10O5. It is not fermented by normal strains of distillers yeasts.

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Any of certain unicellular fungi, generally members of the class Ascomycetaceae, (although a few are members of the class Basidiomycetaceae). Many yeasts are capable of producing ethanol and carbon dioxide by the anaerobic fermentation of sugars. Yeasts are composed of approximately 50 per cent protein and are a rich nutritional source of B vitamins.

Yeast Autolysis.

Yeast Cream.

Yeast Propagator (or Prefermenter).

It is a tank used for the propagation, or development, of a yeast culture, prior to transfer to a fermenter. It is normally fitted with aeration, agitation and cooling devices, and is designed for ease of cleaning and sterilization.

Yeast Recycle.

Yeast Strain.

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A member of the Pseudomonadaceae family of bacteria which is characterized by being gram negative and non-spore-forming. The genus Zymomonas is distinguished by its fermentation of sugar to ethanol. The principal species being examined commercially for fuel-ethanol production is Zymomonas mobilis. It is, however, considered an undesirable contaminant in beverage-alcohol fermentations, in that it tends to produce hydrogen sulphide from sulphur compounds in the mash, particularly that derived from molasses.

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Dr. John E. Murtagh | Resume | Publications | The Alcohol Textbook | The Alcohol Glossary
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