A spectrum of beers
Beer. Øl. Bier. Cerveza. Bière.
This is not a “how to brew beer” blog, because I’m a brewing beginner and there are dozens of great tutorials and hundreds of recipes out there. Instead, this is just a brief exploration of the science and history of brewing.
Back in January, before the Covid-19 virus became a globe-changing phenomenon, I had revived my long-lost hobby of brewing beer after discovering that gluten can be removed from beer, a very exciting revelation in my now gluten-free life. Beer is usually made from barley and/or wheat, both of which contain gluten, and it turns out those gluten proteins survive the brewing process.
In addition to being stuck at home during the Covid-19 pandemic, I’ve recently been on a kick of going back to basics, improving my self-sufficiency, and generally learning how to do things from fundamentals. This winter and rainy spring I spent several (many!) locked-down, self-isolated days immersed in learning about “all-grain” brewing: the equipment needed, the biochemistry involved, the different techniques, the benefits, the added time and complexity, plus the extra possibilities of screwing up.
And so, armed with an internet full of information and looking to update my brewing hobby, I took the plunge into brewing from grains.
Beer has one of the simplest ingredient lists of any food.
The first three on this list were famously made into law in the Bavarian Reinheitsgebot (“purity order”) of 1516. However, neither the 1516 Bavarian law, nor its 1487 Munich predecessor, mentioned yeast, because that critical little microbe had not yet been discovered.
Like most laws, however, this purity order was not quite as pure as it seems…
Hops on the vine. Image: StocksFarm
Besides barley, wheat and rye were also commonly used to make beer back in the day (they still are), but those grains were also used to make bread, and part of the motivation of the Reinheitsbebot was to reduce the demand on wheat and rye, and thus stabilize the price of bread. Another motivator was local protectionism, since imported beers often contained different ingredients. Of course, religion never misses an opportunity to lecture, so the Catholic church got behind this law because many of the other herbs commonly used to flavour malt ales were also used in pagan rituals. Those darn pagans, how dare they worship real things like nature!
In the long history of England ales, a similar law, requiring that beer use hops instead of other herbs, was put into place in 1710, but it was motivated more by tax revenue than by beer purity, since by that point hops were a well-established crop that was taxed by the crown.
Beer and ale? Same thing? Not quite.
Other rulers in other times outlawed the use of hops in brewing to promote their own tastes or agendas, including the archbishop of Cologne in 1380 and Henry VIII of England in 1530. In 16th century England, ale was made from malt, water and yeast, but “beere” was a Germanic malted drink which included hops.
Today, ale and lager are the two primary types of beer, the difference being the yeast and temperature of fermentation. But we have a lot more ground to cover before we start fermenting…
From such a simple set of ingredients… such beauty!
Malting the Barley
The first step in the brewing process it to germinate the barley grains by soaking them in water, drying them, and then repeating for a few days until they sprout (germinate).
Seed grains are little bundles of starch, protein and dormant enzymes all bound up in a matrix and wrapped in a tough outer hull. When the grain is sprouted, several enzymes are activated that break down starch and proteins. At the right point, the grains are dried at around 40C, stopping the germination process but leaving the starches and now-activated enzymes intact.
At this point, the grains are heated to about 80C, which produces a basic “pale malt”, or “base malt”, suitable for making a pale-ale style beer. This base malt is the major ingredient in most all beers.
Beer color is graded on the SRM scale
Malted barley: pale, crystal and chocolate roasted
To add colour and complexity, the freshly malted, moist grains are put into a kiln and heated to a variety of temperatures. This first converts some starches into sugars, and as the temperature increases, the sugars are caramelized, adding not just darker colour but a variety of complex, sweet flavours to the malt. If the grains are dried before being heated, they are toasted, producing flavours and aromas similar to chocolate or coffee. Chemically, this involves the Maillard reaction, the same reaction that toasts bread and browns meat.
Amber and brown ales, black lagers, and stouts are all made from a pale base malt plus a variety of caramelized and/or toasted grains. The mix of malted grains lays the foundation of malty flavors and colour of the beer.
Malting grains is a huge global industry, producing well over 20 million metric tons of malted barley a year. Of course, the vast majority of that goes to the big breweries, but a wide variety of malted barley is readily available to home brewers. Taking it to the next level, keen home brewers are malting their own barley. Maybe some day.
Barley is one of the biggest crops in Alberta, so I shop local for malt, from Red Shed Malting, Red Deer County Alberta, or Canada Malting, whos first malt houses were built in Montreal and Winnipeg in 1906, and Calgary in 1913.
Mashing the Barley
Mashing the grains. Looks like bird-seed soup.
Mashing involves soaking the malted grains in hot water for an hour or so, which converts the starch in the grains into sugar.
Sounds simple. It’s not…
If malting the grains is the foundation of beer, then mashing is the frame. The starch in the grains gets converted into different sugars, most of which will be fermented into alcohol, but some complex sugars will remain. These residual sugars are what gives the beer its malty flavour, and the details of the mashing process determine what types of sugars are produced.
Sugars are a whole family of related organic molecules that are the basic energy source of life. The most simple sugars include glucose and fructose and are called monosaccharides. Disaccharides are two simple sugars bonded together; the most familiar of which is sucrose (table sugar), made of one glucose and one fructose. The important disaccharide in brewing is maltose; two glucose molecules bonded together. Dextrin is composed of three of more glucose units bonded together.
Glucose sugar molecule
Fructose sugar molecule
Maltose sugar molecule
Dextrin with three bonded glucose molecules
Starch is a polysaccharide made of 100s of glucose molecules, linked together by relatively weak chemical bonds into long, branching chains. Because of the weak bonds, individual glucose sugars can be broken off the chain, allowing starch to be digested by plant and animals. Cellulose, which is what gives wood its strength, is also made of long chains of glucose, but bonded together by a stronger chemical bond, and so is not easily digestible.
Single chain and branched chain starch. Image: Wikimedia
The long chains of starch are broken into sugars by enzymes, which are incredible biological molecules that catalyze (speed up) chemical reactions.
Enzymes are a type of protein, and proteins are large, complex molecules made up of chains of amino acids folded into a specific structure. The precise shape of the folded protein is absolutely critical to how the enzyme functions, and how that folding happens is a major area of chemistry research. Basically, the complex structure of the enzyme acts as a molecular scaffold, holding the target molecule in place while the key “active” region of the enzyme facilitates the chemical reaction.
During the mashing process, the starch molecules are broken up into a variety of sugars by two enzymes that are present in the barley grains: alpha-amylase and beta-amylase. The temperature and acidity (pH) of the mash determines which enzyme is more active, and therefore what mix of sugars is produced.
Alpha-amylase works best at 65-70C and pH of 6.7-7.0, and breaks up starch at any point along the chain into smaller pieces, leaving smaller dextrin sugars at the branch joints (within one glucose of a branch). Sugars produced include maltotriose, maltose and glucose. Alpha-amlyase is produced by bacteria, fungi, plants, is present in human saliva, and is a major component of the digestive process in animals.
Beta-amylase works best at 60-65C and pH of 4.0-5.0, and only breaks maltose units off of one end of the starch chain, one maltose at a time. It is slower acting than alpha-amylase, and leaves larger dextrin sugar complexes at the branch joints (3 glucose units from the branch joint). Beta-amylase is produced by bacteria, fungi and plants, and is part of the fruit ripening process, creating sweetness by producing maltose.
In brewing, we want both of these enzymes working together to break up the starch, so the mash temperature is usually kept at 67C with a target pH of around 5.3, resulting in this approximate mix of sugars from a typical malted barley mash.
Effect of mashing procedures on brewing
The simple sugars are easily fermented by the yeast, while the complex sugars will survive fermentation and give the beer a sweet, malty flavour. So from the taste perspective, the mashing process is largely responsible for the dry or sweet character of the beer.
There’s a lot more going on than just this, and traditional mashing involves many different enzymes working on the grain at different temperatures. Over the years, various heating and “resting” phases of mashing were used, to take the grains through a series of temperature regimes for maximum extraction of sugar from the grains.
Boiling the Hops
Measuring the hops
The sweet, syrupy liquid that comes out of the grain mash is the wort. The next step in brewing is to boil the wort and add hops. Hops are the flower of the hop plant (humulus lupulus) and contains acids that produce a bitter taste and act as a preservative, as well as oils that lend a variety of aromas to the beer.
Hops are added to the boiling wort in stages, depending on the desired bitterness. The bitterness of beer comes from the alpha-acids in hops, and those need to be boiled to convert the alpha acids into bitter-flavoured isomers (molecules with identical chemical components but slightly different structures). The bitterness of the beer (IBU) can be estimated with a calculator, based on the alpha-acid percentage in the hops, so guessing is not required when crafting a beer.
Hops also contain a variety of aromatic oils, but because of their volatility, these oils boil off quickly, so aromatic hops are added at the very end of the wort boil, or even in the late stage of fermentation.
There are dozens of different hop varieties, each with a unique mix of bittering alpha acids and aromatic oils. Kegerator.com has an excellent library of hop profiles, including modern hops like Cascale, Simcoe, Amarillo, Citra, and classics like Perle, Tettnang, Fuggle, Saaz and more.
Hops are a relatively recent addition to beer, as for most of the last 7,000 years all manner of different herbs were used to add flavour to ales, and these gruit recipes were of course well-guarded secrets. The first documented addition of hops to beer was in 822AD, where in the Somme Valley of northern France, Abbot Adalhard of the Benedictine Monestary wrote that the duties of abbey tenants included gathering (wild) hops for the brewing of beer. The first mention of the preservative nature of hops was by the famous abbes Hildegard von Bingen, who published a book in 1150 that included a chapter on the hop describing how the bitterness of the hop “keeps some putrefaction from drinks”.
The earliest known cultivation of hops was in Hallertau, Bavaria in the 8th century, and the Hallertau hop is still very popular with brewers today. Tradition lives!
Read more history of hops from the British Hop Association or Zythophile or brewery history.
Fermenting, part I
Transfer from brew kettle to primary fermenter
Primary ferment going strong
“Brewers make wort, yeast makes beer” goes the saying, and it’s very true.
After the wort has boiled, it is cooled down and transferred from the brew kettle into the primary fermentation vessel (also called a “bucket”), where the yeast is added. If all goes well, within 12-24 hours the yeast have started to reproduce and are madly consuming the sugars, producing mostly ethanol and carbon dioxide as waste products. In ales, this frenzy of activity forms a thick layer of yeast and foam on top of the wort; the beer is alive!
Sugar water is denser than pure water, so measuring the density of the wort before fermentation provides a measure of its sugar content. This initial specific gravity reading is called the original gravity (O.G.) and is around 1.04-1.05 for most beers, where pure water has a density of 1.00. The primary fermentation is finished when most of the sugar has been converted to alcohol, and the final gravity (F.G.) reading is much lower, around 1.01-1.02. The difference between O.G. and F.G. is used to compute the alcohol content of the beer.
Specific gravity reading of the wort before ferment.
Final gravity reading at bottling. This dark beer is not the same batch as the light beer!
Humans have been enjoying alcoholic beverages since the first ape discovered that half-rotten fruit still tastes pretty good, and controlling the fermentation of fruit and grains has been a big part of all human societies for 1000s of years, right back to the beginning of agriculture. There is even a theory that beer was instrumental in the rise of civilization itself, the so-called “beer before bread” theory.
Over the 1000s of years that we’ve been making beer, wine, cheese and bread, humans were unknowingly domesticating yeast and bacteria that performed the magical process of fermentation. For most of that time, beer and wine was fermented with naturally occurring airborne yeasts that lived in the cellars of breweries and wineries. In the 1700s two different types of globular structures, visible in the microscopes of the day, were identified as the fermenting agents of beer, but it was not yet known whether they were living organisms or not.
By the 1800s, Saccharomyces cerevisiae (top-fermenting ale yeast, also used for bread) and Saccharomyces carlsbergensis (bottom-fermenting lager yeast) had been isolated and were being sold in Europe. You might recognize the roots of these names…
The science of fermentation is zymology, and was founded in 1856 by the French chemist Louise Pasteur when he observed that it was yeast cells that converted sugars into alcohol. Four decades later, the German chemist Eduard Buchner discovered the enzyme within yeast that was responsible for the actual conversion of sugar into alcohol, a discovery for which he won the 1907 Nobel Prize in chemistry.
Today there are dozens of varieties of yeast available to brewers, in dry or liquid form, each of which contributes subtle flavors to the beer. All the ale yeasts are S. cerevisiae, the same yeast species that has been used for 1000s of years for bread, wine and beer making. Another ancient tradition lives!
Bread yeast and beer yeast are the same species, so can you make beer with bread yeast? Sure!
Fermenting, part II
Resting beer during the secondary ferment
Dry hops in the Black IPA
The vigorous primary ferment takes a few days, after which I like to transfer the beer into a secondary fermentation vessel, to get it off the yeast residue, let is relax, finish fermenting, clear and settle for a few weeks before bottling. Not all brewers do this, and there is some debate as to whether this is a good idea or not.
Hops added to the beer during the secondary ferment transfer most of their aromatic oils to the beer, but do not add much bitterness. Even though the hops get wet, this process is called dry hopping because the hops are not boiled, and is commonly used when brewing IPA and other aromatic, hoppy styles.
At the end of this few weeks of rest, another thick layer of dregs has formed on the bottom of the secondary fermenter, and the beer is much clearer. When the density (specific gravity) is constant over a few days, the fermentation has finished and the beer is ready for bottling. A small amount (130g) of corn sugar is then added, which ferments in the bottles, producing carbon dioxide and carbonating the beer.
And yes, the “beer cozy” is an old sleeping bag, which keeps its temperature more constant and protects the beer from light.
Glow in the dark IPA, still mostly water.
Water is the main ingredient in beer, and the differences between the chemistry of the water in various parts of the world is one the reasons that different beer styles have evolved. Being a beginner, I have not yet dived into water chemistry (haha!), so there’s lots of reading to do, starting with the water chemistry section of How to Brew by John Palmer. Blulosophy also has an excellent article on the importance of water chemistry in brewing.
The measure of acidity / alkalinity in water is pH, and the mashing process is quite sensitive to pH because the amylase enzymes are sensitive to pH. The pH scale of acids and bases was introduced by Danish chemist Søren Peder Lauritz Sørensen, working at the Carlsberg Laboratory in Copenhagen, studying… brewing, of course.
A small amount of chlorine in the water is good, but the typical level of chlorine in tap water is much too high. There are a variety of ways to remove chlorine.
The beer keeners at BluLosophy have run a variety of ex-beer-iments on water chemistry and how it affects beer.
Home Brewing Resources
One bottled beer batch
Combine 1000s of years of history, scientific discovery and brewing craftsmanship with an internet full of fanatical brewers, and you get a tremendous amount of information on home brewing. Here are some of my favourites.
A great place to start is the classic book How to Brew by John Palmer.
Lots of beer recipes, including Brewers Friend, Beer and Brewing, Beer Recipes and the Home Brewers Association.
Briess Malting has great history and background of malting, plus recipes.
Brülosophy is a group of citizen beer-scientists who document all manner of ex-beer-iments and taste tests.
Kegerator has a great collection of hop acid and aroma profiles, plus recipes and tutorials.
Brewer’s Friend has calculators for color, alcohol content, bitterness, mash water volume, and more.
Taking it to the next level with tutorials on malting your own grain at Beer Smith and Brew Cabin. And yet one more level by growing hops in Alberta.
Hopefully all this will make you appreciate your next beer a little more. Cheers, skål, prost, salud, santé!
– Darren Foltinek, April 2020