Okay, you already know that beer is a combination of water, grains, yeast and hops.
But really, what does that mean? It means we owe a great deal of our happiness to the hardest working employee in the brewery, the single cell organism called yeast, who tireless converts sugars to alcohol. Without yeast, beer would just be a sweet barley tea or something like porridge. Who’s going to get excited about that? Here is the simplest explanation of how yeast work their magic:
- Grains—typically malted barley, rice or corn—are heated in water to optimum temperatures to activate enzymes to break the grain’s starches into simpler sugars. This makes a very sweet tasting liquid called wort. What?!? Did we say rice or corn? Maybe you’re saying “Hey the German Purity Law….”. We’ll talk more about that in another post.
- The wort is then cooled to a temperature, e.g. 17 C, that is optimal for yeast to eat the sugars and convert them to alcohol and CO2 gas. When fed the wort, yeast explode into action—eating, kicking out alcohol, reproducing, eating, kicking out alcohol, reproducing—until the sugars are consumed or the alcohol level starts to shut down the yeast.
- Hops and other botanicals are added during the process to balance the sweetness of the liquid and create aroma and flavors. There are currently around 80 kinds of hops used in modern brewing to create different levels of bitterness and fragrance in beers. Hops also have strong anti-microbial properties, which helps preserve beer longer.
- The beer is allowed to rest and mature for some time which allows the yeast to settle to the bottom of the tank and for the taste to develop.
- Then the beer is transferred to packages such as bottles, cans and kegs to reach the thirsty consumer.
In the craft beer industry, this process typically takes close to a month. Mass produced beer can go from grain to glass in less than half the time.
Mass produced beers typically use one to two kinds of base malts coupled with low cost hops. Production happens with massive, highly automated systems to achieve a beer flavor that is always consistent and appeals to the largest number of people at the lowest price point possible. Mass production has become the norm in order to meet huge global demand, but in the past three decades, craft beer has been making a come back. (At one time, all breweries were small and crafty).
When people talk about craft beer, they mean beer that is produced in smaller batches with a heavy focus on richer mixes of malts (grains) and more pronounced use of hops to give the beer more depth, greater aroma and often higher alcohol when compared to mass produced beers. This beer is called craft because the brewer is more intensely involved in all steps of production and must also apply artisanal skills to achieve the desired flavor and consistency from batch to batch.
Beer is not difficult to make. It has been done on wood fires with clay pots and in farmhouse kitchens for much of human history. Today’s beer, though, tastes very different than the brews made through most of our history. Today, beer is generally clearer, cleaner tasting and more consistent that centuries past because our knowledge base is more uniformly taught amongst brewers and our technology is cleaner.
When you visit a brewery you may be struck by all the stainless steel, pumps, hoses, pipes, canning equipment and water everywhere. All of this equipment is designed to allow brewers to create optimal conditions to extract the right sugars from grains and feed those to yeasts under optimal, controlled conditions. Key to all good brewing is cleanliness. Breweries are made with lots of stainless steel to allow the brew team to wash down and sterile all parts of the system that comes in contact with the beer.
If you hear about “infected beer” that typically doesn’t mean the beer is spoiled and will make you sick. Humans have been drinking “infected beer” for most of our history, and that infected beer was generally safer than the usual water sources. When a beer is infected, it means there are other wild yeast types, bacteria or fungi competing with the pure yeast strain used by the brewer. This creates flavors or aromas that change the taste of the beer. That change is often not desired by the brewer but sometimes it may pleasantly surprise the brewer.
Modern brewing equipment is designed to minimize infections and allow the brewer to produce the same flavor of a beer time after time. This is what consumers generally prefer.
The brewery looks complicated but is conceptually simple, as follows:
You have a big kettle called a mash tun which is where the malts are boiled to release sugars. This mixture is called the “mash”. It looks (and tastes) like porridge. This mash may go through two temperature changed to extract two different groups of useable sugars to feed the yeasts during fermentation.
After mashing, the mixture is strained through a process called lautering. This giant strainer may sit at the bottom of the mash tun or may be a different vessel. Lautering simply separates out the liquid, now called “wort”, from the solids.
The wort is now boiled for a period to further break down the sugars and to allow bettering to take place by boiling in hops and other flavors (such as orange peel, flowers, etc.). Once hops are added, the wort gets a bit cloudy from all of the suspended hops. This liquid is then pumped to another vessel where it spins around the edge of vessel creating a whirlpool before it is ready to pump to the fermenting side of the brewery. The whirlpool causes much of the hop particles to settle into a cone shaped pile in the middle of the vessel.
After the whirlpool the hot wort, which is at around 65-80 C needs to be cooled down quickly to a temperature that yeast require, such as around 18C. This is done by pumping the hot wort through a heat exchanger.
The vessels for mashing, lautering, boiling and whirlpooling are called the brewhouse or brew deck. We often refer to it as the hot end of the brewery.
Once the wort is cooled it goes into fermentation tanks. Those are usually cone shaped to allow the brew team to remove the used up yeast, hop particles and other solids that settle to the bottom of the tank during fermentation and resting. Yeast and additional hops are added to the wort and the system is closed to allow the yeast to get busy converting sugar to alcohol. When fermentation and resting are complete, you have beer.
The beer is now ready to drink. For brewers and visitors, it’s a joy to draw the first taste of a beer from the tank.
Finished beer is then transferred into cans, bottles or kegs and sent on its way to eager customers.
Did you know that Japanese Sake is not really a wine? It’s more like a beer. It’s brewed similarly to beer by mashing rice to extract fermentable sugars and then fermenting with Koji mold (Aspergillus oryzae) instead of yeast. We throw this out there because beer can also be made with rice and other grains.
A lot is said about real beer containing only water, malt, yeast and hops with authoritative sounding references back to the German Purity Law of 1516. (Note: the law said nothing about yeast which was not understood until 1857 when Louis Pasteur explained the fermentation process). By malt, most people think of barley malt. Today, breweries use many grains including barley, wheat, rye, rice and corn to produce beers of varying color, lightness, maltiness, viscosity, head retention and flavors.
It is possible to take most grains in their raw form and boil them in a two step process (called decoction or cereal mashing) to eventually extract a sugar rich wort useful for beer. This process has been made more efficient by using grains that are malted, particularly barley. Malt is a grain that has been soaked in water and allowed to start to germinate before quickly drying the grain. During the start of germination, enzymes in the grain become activated for the purpose of converting stored starch into sugar to feed the growing plant. These enzymes are very efficient at converting starch to sugar and are therefore released as a part of the malting process. The malt then is infused with the enzymes which speed up the release of fermentable sugar during the first step (mashing) of making beer.
Barley is the standard grain for beer. It can be roasted to produce various colors and flavors in beer. Depending it’s variety and how it is roasted, barley malt can produce colors that range from light to amber to dark and flavors that range from crisp to caramel like to chocolate to coffee.
Hops are the cone-like flowers of a climbing vine found in North America, Asia, and Europe. Hops contain powerful aromatic oils that lend bitterness and fragrance to beer. Under the leaf like covering of the cones, there are yellowish magical glands called lupulin glands, responsible for the alpha acids and polyphenols that give the beer it’s signature bitterness and great smell.
Currently, there are an approximate 80 different varieties of hops used for commercial brewing. These hopes fall into three main categories:
- Bittering hops contain the highest amount of acid out of the three categories, and often gives the beer a slight bitterness.
- Aroma hops have slightly lower levels of alpha acids, but have a more pronounced flavor and aroma. Aroma hops are often used in conjunction to bittering hops to produce the most intense flavor range.
- Dual hops have a mid-range amount of acids as well as a good smell and aroma, allowing it to be used for both bittering and aroma.
To bitter a beer, hops are added during the boiling off the wort for typically 45-90 minutes to isomerize the alpha acids. Most modern craft breweries now add hops at various times during the boil to bring out different flavors.
For example, there is the method of hopping is called ‘finishing’, in which hops are added to the tank 15 minutes before the end of the boiling cycle. This means that less of the aromatic oils are lost by evaporation, as well as more of the hop aroma being retained.
Dry Hopping is when hops are added to the fermentation tank late in the cycle for increased hop aroma. The hops are then circulated in the tank to get the freshest hop flavor possible. This is a preferred method when making highly hoppy and aromatic beers like IPAs.
In the past, knowledge of yeast was essentially non-existent. In the days of the Vikings, each brewing family had a ‘totem stick’ that they would mix the wort with. This stick would ensure that the beer would turn out just right. Of course, we know now that this was a result of the family yeast culture being transferred by the stick. Brewer’s Yeast (Saccharomyces cerevisiae) is technically considered a fungus. The way yeast functions is by consuming glucose and maltose (simple sugars), and then producing carbon dioxide and alcohol as ‘waste’ products.
For the most part, there are two types of yeast used in mainstream brewing: ale yeast and lager yeast. Ale yeasts are top fermenters, with most of the action taking place at the top of the fermentation tanks (as the name suggests). Lager yeasts–on the other hand–prefer the bottom of the tank. These are not the only difference, however. Ale yeasts like warmer temperatures, and will go dormant below 12C˚ (or 55F). Lager yeasts will continue to work in temperatures around 4C˚ (or 40F). From this we get the term lagering which refers to the practice of letting a beer ferment and condition very slowly at cold temperatures.
Before the advent of the microscope (and explanation of the role of yeast by Louis Pasteur in 1859), it was truly one of the great wonders of nature how beer could magically change from a sweet wort to the alcoholic gassed drink we all love. See our article on Proof of God’s Love in the Beer Yore page below.
The most important thing to understand about yeast is that they are truly the hardest workers in any brewery. They also get really cranky if their living conditions are not to their liking. They don’t deal well with stress. It makes them kick off unusual or unwanted flavors. Sometimes, though, that is good and sought by brewers. For example, it only takes a 1 degree Celsius change in fermentation temperature for a Wit beer yeast to go from making neutral or clove like flavors to banana like flavors. The brewer then dials in the temperature according to which flavor is sought for the beer.
Breweries are obsessive about cleanliness. That’s because wild yeasts, molds and bacteria can rapidly infect a tank of beautiful beer and convert it to something completely different or unwanted. For the most part, a brewery wants to keep a single yeast busy fermenting the beer with no competition or unwanted visitors. There are, however, beers that are intentionally fermented with wild type yeasts lending sour and funky tastes. There are some amazing pioneering beers emerging now by going wild.
The wildest yeast story we know, though, is of the Polish brewery that is fermenting beer from a donor’s personal yeast. Yeah, that kind of thing really happens.