Homebrew: Fermentation

During Advent I started writing about brewing beer at home, but I got distracted and didn’t finish all the posts. So far we’ve discussed mashing and boiling, so now we move on to fermenting.

Rocky head formed during fermentationThis post is about fermenting homebrewed wort to make beer.  I wrote it on a Tuesday afternoon.  Earlier that day I had gone to Sherbrooke Liquor and found that they had bottles of Muskoka Spring Oddity (750 mL, 8% ABV) on sale for $6.99.  I first tried this beer in the summer of 2012, and thought it was pretty good: broadly in the witbier style, malty, cloudy, aromatic, laced with spices.  While I would never turn down a glass of Oddity, the truth is I’ve been buying and consuming it in large quantities to get the bottles that it comes in, which are shaped a bit like a Burgundian wine bottle, but with those wire swing caps that are so coveted by homebrewers.  The short version of the story is that I got pretty drunk while writing this post.  It begins with a lengthy digression on the language we use to describe and classify beer.  There are a few comments on yeast, and then the article ends with a completely inappropriate condemnation of the Anchor Brewing Company.  The tone could only be described as belligerent.  Enjoy!

About Yeast.  Yeast is a fungus.  If anyone ever tells you it’s an algae, punch their mouth.  That’s not true.  Besides converting sugars to alcohol, yeast makes very important contributions to beer aroma and flavour.  The banana and clove aromas found in most Bavarian Weissbier are created by the unique strain of yeast, Torulaspora delbrueckii.  Try saying that five times fast.  Many breweries cultivate their own yeast strains, but smaller operations and homebrewers tend to buy yeast from companies like Wyeyeast.  There are different strains designed for different styles of beer.

Many folks will tell you that the difference between lager and ale is the type of yeast used.  I want to take a few hundred words to discuss this.

Beer Language: Beer v. Ale v. Lager

Despite what the modern beer geek tells you, the words beer, ale, and lager are commonly and correctly used in different ways by different groups of people.

Ancient brewing traditions were very insular.  Brewing in England, for instance, had nothing to do with brewing in Belgium or Germany until maybe the sixteenth century.  Before the modern era, British brewers didn’t even use the word beer: they called their drink “ale,” which is derived from an old Saxon word, “alu.”  Traditional British ale was a malty, low-alcohol brew.  It wasn’t bittered with hops like modern beer.

On the other side of the channel the Belgians and Germans and others had their own, distinct ways of making a drink they called “bier” or “bière” depending on the region.

In the modern era, a couple of Bavarian beer inventions forever changed how beer would be made. First of all they started using hops to bitter beer instead of the traditional gruit mixture.  They found that hops preserved the beer much better than any other herb or spice, and this caught on in such a big way that beer is now bittered exclusively with hops all around the world.

This concept was entirely new to the British.  They were slower to adopt it, and even once they did, they used much less hops than their continental friends.  Most traditional English ales (pale ale, mild, bitter, et c.) are very lightly hopped.  India pale ale is a notable exception.

The second important Bavarian invention was lagering.  From the German word meaning “to store,” lagering is simply keeping beer at near-zero temperatures for several weeks to let it clear.  Lagers are now the rulers of the beer world: all of the hugely popular flavourless beers – Bud, Coors, Molson, Corona, Miller, Tsang Tao, Stella, and so on – are lagers.

What the words beer, ale, and lager, mean to a Briton.  Many British folks still make the distinction between British ale (even though it is now lightly bittered with hops), and beer (the continental drink aggressively bittered with hops).  The British language makes the distinction between these two ancient brewing traditions that in modern history have merged, or at least greatly influenced each other.

What the words beer, ale, and lager mean to a North American.  For North Americans, “beer” is any alcoholic drink made from grain, and every beer is either an ale or a lager.  Laymen think that lagers are gold and clear, and ales are dark and cloudy.  Beer geeks think the distinction is in what species of yeast is used to ferment the drink, lagers using Saccharomyces pastorianus, “bottom-fermenting yeast,” and ales using Saccharomyces cerevisiae, or “top-fermenting yeast.”  To me, both of these distinctions are inaccurate and completely useless.

First: not all lagered beer is gold.  There are about one zillion examples of classic styles of beer that are lagered but dark in colour.  Bocs, for instance, including maiboc, festboc, heller boc, dunkelboc, doppelboc and all the other various incarnations.  Closer to home, Creemore Springs is an example of a lager that is chestnut in colour.  The Alley Kat fall seasonal this year was an Oktoberfest beer with an amber colour.  It was  lagered.

On the other side of the coin, there are countless ales that are pale in colour.  Kölsch, for instance.

As one more little monkey wrench to throw into this complex machinery, what if I were to use “lager yeast,” but otherwise treat the beer as if it were an ale, ie. ferment it at warm temperatures?  Is the resulting beer a lager or an ale?  (There is a style of beer that does this.  It was first made in California in the nineteenth century, and at that time it was called steam beer.  The Anchor Brewery of San Francisco now holds a trademark on that term, so the style is called (groan) California common.[1])

Anyways.  Any useful classification of beer has to include process-oriented information, like what type of yeast is used, but also consider the tradition from which the beer comes.  What is the point of grouping English pale ales and Trappist beer together because they both use “ale yeast”?

Let’s get back to fermenting homebrew wort…

Wort Aeration.  Before yeast starts metabolizing sugar, it reproduces, a process for which it requires oxygen.  It’s helpful to the yeast if you aerate your wort.  This can be done in a number of ways.  I just cascade the wort between two large tubs are few times.

Primary and Secondary Ferments.  I think these terms might be falling out of favour, but I still distinguish between primary and secondary fermentations.  Within twenty four hours of pitching the yeast, a frothy head should form on top of the wort.  You can hear the wort hissing and bubbling.  This is the primary fermentation.  After maybe five to seven days, this head will disappear, and the fermentation will slow down considerably.  I rack the beer at this point, that is, syphon it into a different container.  I call this secondary fermentation, it takes another week or so.

As the yeast consumes the sugars in the wort, the density, or gravity, of the liquid drops.  The sugars in fruit juice are simple, and yeast has no problem metabolizing all of them.  This means that if cider or wine fermentation is left to its own devices, there will be no residual sugar, and the final drink will be “dry.”  The sugars in wort, however, are a good deal more complex than those in fruit juice, and depending on the style of beer, there may be a lot of sugars that the yeast is unable to metabolize.  This concept is called attenuation.  Highly attenuated beers are dry and crisp.  Low-attenuated beers still have unfermented sugars, and typically have a richer mouthfeel, maybe even an impression of sweetness on the tongue.  Examples of highly attenuated beers: most commercial lagers, Pilsner, et c.  An extreme examples of a low-attenuation beer would be the Trappists, like Westmalle and Chimay.  Our first batch of beer, an English pale ale, finished fermentation at 1.015 specific gravity.

Brewers can adjust the texture and flavour of their beer by adding sugar to the wort, or by using adjunct grains like corn and rice that naturally contain simple sugars.  Budweiser adds corn to their malted barley.  Many British brewers will add sugar to their wort to slightly thin out the mouthfeel of a pale ale.

Once you have reached your target gravity and fermentation has stopped, you have beer.  It’s time to get it into a bottle, or maybe a keg.


1.  You know how lots of brand names and trademarks become so popular that they become the common noun?  I’m thinking of Kleenex (a “tissue”), Google (“search engine”), and Xerox (“photocopy”  I probably just dated myself…)  Sometimes these companies pay for ad campaigns that discourage people from using the trademark when it doesn’t apply to their products.  If you don’t know what I mean, read this page from the Popsicle® website, which had me on the floor laughing.  (Oops: just dated myself again.  I mean it had me rofl…)  A disciplinary grammar page on a website for frozen confections:  hilarious!  I’m definitely going to make some Evans cherry “ice pops” next summer.

So, there used to be a style of beer called steam beer.  It was developed in California during the gold rush.  Brewers used lager yeast, but otherwise treated the beer like an ale.  Like so many great historical styles, steam beer fell out of favour and basically went extinct.  In 1971 the Anchor Brewing Co. made a beer in this style, then took out a trademark on the term “steam beer,” so that other beers made in this style can’t use the term.  Granted, Anchor Brewing deserves credit for reviving a unique species of beer, but honestly I wish the beer geek establishment would just take back the term steam beer.

Consider an analogous situation.  In nineteenth century Belgium, on the border between the French region of Wallonia and the Flemish Flanders, there was a region in which a style of beer called wit, or white, was popular.  Over the course of the twentieth century it too fell from favour, and in the 1950s the last witbier brewery closed.  About a decade later, a dude named Pierre Celis made a beer in that style and called it Hoegaarden.

Of course, brewers can still make steam beers, so what’s the big deal if they have to call it “California Common”?  At the risk of sounding like Britta on Community, I have to say that I am a huge believer in the relation between politics and the English language.  “Steam beer” is the drink that they consumed in the muddy squalor of the gold rush.  “California common” is a sanitized euphemism for a beer that should be considered one of America’s great contributions to the pantheon of classic beer styles.