First things first: Before the brewing begins, the brewer has to decide what style of beer he/she wants to make. That decision informs a whole lot of choices: Quantities of ingredients, additional ingredients (or not), temperature and duration of brewing time and any additional processes key to making a specific style of beer.
To begin, the brewer makes malted barley out of barley husks. To make the malt, the barley is immersed in water, where it germinates, or sprouts. The sprouted barley is then dried in a kiln. Within wide time and temperature variations, the creation of many different malts is possible, from the pale malts of pilsners to the roasty malts of stouts and porters—and everything in between. Note that not every brewer malts his own barley. Various types of pre-made malts are commercially available.
A mill cracks open the malted barley kernels with steel rollers, exposing the starches inside. Starches convert to sugar and later convert to alcohol. We call these broken kernels “grist.”
Next, the grist goes into the mash tun, where hot water is added to make “mash” with a porridge-like consistency. In just about an hour, the hot water has acted as a catalyst to convert starches to sugars. The result is called the wort, a mixture of barley husks and sweet liquid. It’s also known as sweet wort, because bittering hops haven’t yet been added. This water temperature plays a big role: 145 degree water makes for highly fermentable wort, for crisp, dry beers, where 155 degree water creates fewer fermentable sugars in the wort, creating sweeter, richer beers. Once the desired wort is arrived upon, the temperature is jacked up to 170 degrees, ending the conversion of starches to sugars completely. The result is a wort that is less viscous and easier to separate from the mash. This is what’s known as mashing out.
The lauter tun acts like a big sieve, separating the barley kernels from the liquid that will become beer. To increase the level of filtration, some of the first wort to be separated may be put back through a second time. This is known as recirculation. Additional water may also be added in a process called “sparging”. In an attempt to get every last bit of extractable sugar out of the mash. Sparging is sometimes done continuously through the lautering process, or done separately, creating two worts from the same batch of mash. The brewer can opt to combine the two worts into one, or keep them separate and create two types of beers. Temperature has an effect in sparging: too cool and you won’t extract many more sugars. Go too hot and the wort becomes bitter.
This is an optional step in the brewing process that allows the brewer to increase capacity. The wort receiver holds the separated wort until it is ready to be transferred to the kettle for the next step. It allows the wort to be collected there before it is sent to the brew kettle, which, in a large brewing operation, would still be brewing the previous batch of wort to come through the lauter tun.
The wort is collected from the lauter tun and is transferred to the brew kettle. The brewer checks to make sure that the sugar concentration is at the desired level. It’s measured as a sugar percentage by weight, and is known as the original gravity of the wort. The wort is boiled, and then hops are added. The boiling does three things: first, it sterilizes the wort so that later, when yeast is added, the yeast is the only microorganism in the wort. Second, it extracts the bitterness from the hops, flavoring the beer to the brewer’s design. Lastly, it coagulates malt proteins so that they can be skimmed out along with the hops. After the first round of hops, additional hops can be added. The hops added later are typically for aroma, as these hops are not in the kettle long enough for the aromatics to be boiled away. The brew kettle step typically takes no more than two hours. After that duration, the wort could become more bitter than desired.
With the hops now added to the wort, it’s now called “bitter wort.” And the hops and proteins need to be skimmed off. Here, a whirlpool action draws all solid matter to the center of the tank and the wort can be drained off from the edges.
Again, active temperature management is a key consideration for the brewer. At this point in the fermentation process, the wort needs to be cooled. If cooled too slowly, unwanted chemicals can be released in the wort and you run the risk of microbial contamination. So a heat exchanger is used to cool the wort down fast. The heat exchanger runs cool water separated by a thin plate from the wort, which is piped in the opposite direction. Once the wort is sufficiently cooled (40-45°F for a lager, and above 55°F for an ale), it’s added to fermentation tanks, where the yeast is introduced.
This is primary fermentation. The fermentation tanks mark the only time oxygen is freely introduced and in contact with the liquid. Aerating with oxygen helps the yeast split into multiple cells. Once the oxygen is depleted, the yeast reacts by consuming the glucose, maltose, and maltotriose (sugars). The reaction of the yeast causes the temperature of the liquid to rise and brewers watch this closely, taking cooling measures as needed. The liquid needs to stay at an acceptable temperature range for the specific beer being brewed. The wort can now be called beer!
Fresh out of the fermentation tank, as you can imagine, the beer is full of yeast and particulate matter. When these are strained out here, rendering it a clear liquid, it’s referred to as “bright beer.” But here again, the brewer must take care to not filter out what makes this beer style what it is. The correct color and flavors must be preserved. Some brewers surpass the sterile filtering by pasteurizing their beer, getting it just hot enough to kill the yeast and any other bacteria.
This process is considered the secondary fermentation. Once the beer is at the desired gravity, it’s cooled and conditioned in a bright beer tank. Here, the flavor is refined. Ales take less time, lagers take longer and are conditioned at lower temperatures that are near freezing.
If the brewer chooses to add carbonation to the beer prior to bottling or casking, a second filtration is done. A more natural approach to adding carbonation may also be used: The brewer leaves a small amount of yeast and sugar in the final product to allow natural fermentation that produces carbonation in the bottle or barrel. They call those continuously fermenting beers “real ale.”
Keg racking or Bottling line
The brewer can package the beer in kegs, bottles or cans. Going the keg route, he can sell to bars with draft lines or to stores that rent taps.
Refrigerated storage and transport
Whether pasteurized or unpasteurized, beer is ideally kept refrigerated to improve shelf life. Unpasteurized beer, in particular needs to be kept at around 38 degrees and will have a shorter shelf life than its pasteurized cousin. So, from the brewer, the beer is transported to refrigerated warehouses (either their own or to those of their distribution partners) where it awaits being ordered. All in all, it takes about four weeks to get an ale to this point and typically, six weeks for lagers.