Brewing Terms

Yes, we know most of you are experts and already know about these things, but our mission is to help people get into home brewing in any way we can. We thought it might be useful to maintain a quick reference guide for all those jargoney words that go completely over the head of people new to brewing.

Let us know if you think of anything we should add to this list...


We'll start with a nasty one. Even lambic brewers don't want this bacteria. Acetobacter creates acetic acid, which is essentially vinegar. If your beer has it, throw it out.

Alpha Acids

Chemical compounds found in the resin glands of the hop flowers used in beer brewing that provide bitterness (usually measured in IBU) when heated (during the boil). The higher the alpha acid rating of a variety of hop, and the longer its boiled for, the more bitterness it will add to the beer.


How effective the conversion of sugar to alcohol and CO2 is.  A yeast that is more attenuative will consume more sugars, resulting in a higher alcohol content and usually a drier finish.  A low attenuating yeast will generally finish leaving more sugar behind, resulting in a sweeter beer.


Sometimes called the British Fungus, or more commonly by brewers, just "brett", brettanomyces is a strain of yeast that lives on the skin of fruit. Discovered in 1904 by Carlsberg brewery lab tech Niels Hjelte Claussen, there are five main strains. In most beer styles, it's unwelcome, but in some beer styles, such as lambics, b. lambicus or b. bruxellensis can be an essential ingredient, introducing aromas often described as "goat" and "horse blanket". 

Dry Hopping

The practice of adding hops during fermentation, as opposed to during the brew.


Gravity is used to discribe the density of the malt sugar in the wort or beer. Original Gravity or Starting Gravity (OG or SG) is how much sugar is present before fermentation. Final Gravity (FG) is how much sugar remains after fermentation.  The difference between the two calculates the alcohol content in the finished beer.


Usually refers to the flowers of the hop plant (Humulus lupulus) which is commonly used in making beer. Hops are added at different stages of the brewing process in order to produce different results. For example, hops added during the boil produce bitterness, hops added towards the end produce flavour and hops added when the heat's turned off are aimed at adding aroma. Some varieties of hops are specifically known for their bitterness, flavour or aroma qualities.


An often misunderstood measurement of a beer's bitterness, IBU stands for International Bitterness Units. There are other bitterness scales, but IBU is the most commonly used and widely accepted standard.

Basically, the lower the number, the less bitter the beer.The scale realistically starts at around 5 for something like a light lager, moving up to 100 for something like a bitter Imperial IPA. In theory, beers can exceed 100 on the bitterness scale, but it's usually difficult to detect and therefore pointless, unless there's a serious amount of malt flavour disguising the bitterness. For example, an Imperial Stout with an IBU of 50 can taste less bitter than an English Bitter with an IBU of 30, because the stout uses much more malt.

(see Alpha Acids above)


A bacteria, or rather, a group of bacteria that can be both good and bad in a beer. Lactobacillus can be used to create sour beers, such as lambics, or it can spoil an otherwise perfectly good beer. Lactobacillus "eats" the sugars in the wort, creating lactic acid as a by-product. This lowers the pH of the beer, which makes it "astringent" or sour. Great if you're brewing a lambic, but a waste if you're aiming for a pale ale.


Process of separating the spent grain from the liquid wort


Grains that have been harvested, germinated and dried just as they thought they were going to turn into a nice barley plant.


A steeping process with grain in heated water which allows the conversion and extraction of sugars to create wort.

Mash Tun

Many smaller breweries mash in using their boil kettle or lauter tun, but as breweries scale up, it becomes economically sensible to improve the efficiency of the mash (by getting the most sugar they can out of the grain) by using a dedicated vessel, called a mash tun.


As nasty as this sounds, it's actually not all bad. Pediococcus is a bacteria related to lactobacillus and found on many processed meats like salami and chorizo. It's also used in making sour beers because it's capable of digesting the long, complex sugar chains that normal brewer's yeast can't.


Basically adding yeast to wort to start the fermentation process. If the wort is too warm or too cold the yeast will die.

Primary Fermentation

Vigorous fermentation when the yeast cells are rapidly reproducing and feeding on the sugars in the wort while they release alcohol and carbon dioxide.


This is the addition of sugars at bottling or kegging to create carbonation.


Pumping or manually collecting the wort in the mash from the bottom and pouring back in the top to aid in filtering the wort through the grain. The method of clarifying the wort during the mash.


A stage of the mashing process during which complex glucose chains are broken down into fermentable sugars, mainly maltose.


A genus of unicellular, saprophytic fungus that includes many types of yeast. Among these, the yeasts used in the brewing process are grouped into two main categories:

Lager yeast (bottom fermenting) - saccharomyces carlsbergensis/saccharomyces uvarum/saccharomyces pastorianus

Ale yeast (top fermenting) - saccharomyces cerevisiae

Secondary Fermentation

After the very active primary fermentation, fruit and other sugars can be added to the fermenter which will ferment out.  A secondary fermentation is useful to reduce stress on the yeast if there are a lot of sugars or a high initial gravity.  Stressed yeast can produce off flavors.  
Another form of secondary fermentation is pitching a different yeast into the fermentor or at bottling.  This creates a more complex yeast flavor profile and can alter the carbonation as well as how the beer conditions in the bottle.
Priming is also a form of secondary fermentation and is the process of adding a small amount of sugar at bottling which ferments out and creates teh desired carbonation.


Gently rinsing the grain with hot water to remove the remaining fermentable sugars.


Pronounced 'Wert' - The malty sugary liquid resulting from the mash which is then boiled before fermentation.

Wort Chiller

A piece of equipment used to rapidly chill the wort to the ideal yeast pitching temperature.  Many types are available including: Immersion Chiller, Counterflow Chiller & Heat Exchanger.


Brewers make wort - yeast make beer.  The micro-organism which converts sugars to alcohol and CO2. There are millions of strains of different yeasts, each producing different results and only some of which are good for brewing.