The Yeasties, The Yeasties – The Beasties in my Beer!

Posted on Posted in Beer History, Myths, Sour, Yeast
A Diagram of a Yeast Cell

Lately, I’ve noticed a trend in the beer blogging world.  People have been misusing the terms “Ale” and “lager.”  Amongst some folks, Ale has come to mean a craft brewed beer of quality while Lager means a mass produced yellow beer of poor quality.  Other folk just use the terms incorrectly, calling a lager an ale or vice versa.  In the United States, it’s further complicated by the often nonsensical and arcane liquor laws left over from Prohibition.  Several years ago, Bridgeport Brewing couldn’t release their “Beertown Brown” in the state of Texas because it had the word “beer” on the label but an alcohol level over 5%.  In Texas, beer has to be under 5% while Ale is for products over 5%.  While the brown was techincally an Ale, it had the word “beer” on the label.  Silly laws and poor education have created a situation where words with specific and important meanings are being warped.  Clearly Ale doesn’t mean a good
beer, anyone who has tasted Budweiser’s American Ale knows this to be true.  Nor does Lager have to be a bad beer.  One drink of a fine schwarzbier will persuade you otherwise.  But what do these terms, the most basic and key terms of the beer world, mean?  And beyond their basic meaning, what is their role in the making of beer?

The first part of our dilemma lies with our friend the yeast.  The saying in the beer world goes: “Brewers make the wort, but yeast makes the beer.” (Wort is the sugar rich mixture of malt, water and hops that the brewer makes prior to fermentation.) Yeast is a single cell fungus that eats sugar and puts out alcohol, CO2, and other flavor components.  Without this biological function, we’d not have beer.  So, despite Texas law, beer is everything that yeast creates from wort (pronounced “wert”). But how do we get Ales and Lagers?  Well, they’re actually two different species of yeast.

Ale – Saccharomyces Cerevisiae

Saccharomyces translates to “sugar fungus,” while cerevisiae means “of beer” or “sugar fungus of beer.” S. cerevisiae, or ale yeast, has been the primary fermenter of beers for thousands of years.  Sometimes ale yeast is referred to as “top-fermenting” yeast, which means that the yeast would rise in the tank during fermentation.  It would from thick mats during the turbulent fermentation which would float up on the CO2 bubbles the yeast was producing.  This is less true now, due to the use of conical fermenters and newly bred yeast strains which encourage yeast to drop so it can be collected and reused more easily.  Because ale yeast is thousands of years old, it’s had a long time to create a lot of genetic diversity throughout the world.

Open Fermenters at La RullesThink of the classic ale producers of the world.  If you made one type of beer and used yeast strains from Bavaria (hefeweizen yeast), Belgium, and England; you’d get 3 different beers.  Each beer, while having the same base wort, would taste radically different based on the yeast used.  Look at a homebrew shop sometime.  They have loads of yeast options.  All of them are S. cervisiae, but they’ve had thousands of years of evolution, natural or directed by humans, to create different traits.  Besides the old catch-phrase of “top-fermenting,” the other common ale yeast traits include an ability to ferment at “room” temperatures and an inability to ferment the “disaccharide melibiose” (a complex sugar).  Because ale yeast ferments at warmer temperatures, it throws off a lot more by-products (besides alcohol and CO2):  the classic ester and phenol flavors and aromas so beloved of ale beers.  That banana smell of a Bavarian Hefe? Ale yeast by-product.

Lager – Saccharomyces Pastorianus

Named after Louis Pasteur, S. pastorianus is newer species of yeast.  It’s actually a natural hybrid of S. cerevisiae and S. bayanus (wine yeast).  S. pastorianus, lager yeast, was created or evolved in Bavaria due to the laws requiring brewing during the cold months (see my discussion on the Reinheitsgebot for details). Prior to the ability to isolate and protect your yeast strains, most would have been a mix of various sugar loving yeasts which would have been S. cerevisiae and S. Bayanus.  S. bayanus, however, likes and survives at much lower temperatures than S. cerevesiae.  Through successive winters, the two yeast interbred and created a new yeast that worked well in colder fermentation situations.

Often called “bottom-fermenting,” S. pastorianus ferments much more slowly than ale yeast so it didn’t form the thick mats that would float to the top which then could be collected by the brewer for the next batch.  Instead, the lager yeast that dropped survived and thrived would be collected for re-use from the bottom the storage or “lagering” vessels.  Thus, through natural selection, the Bavarians created lager yeast.  Because the yeast fermented at colder temperatures, it fermented slowly.  This slower fermentation allowed the yeast to more thoroughly eat the sugars in the wort while not throwing off a lot of the by-products that created ale flavors.  But the process wasn’t done yet, the flavors were still raw and green so the beer had to be stored for a while to mature, hence the name “lager” which means to store.  The result was a beer that was cleaner and crisper tasting.

Eventually, Lagers grew in popularity because of their clean, easy to drink flavors.  This, coupled with Germans emigrating throughout the world, led to an eventual dominance of lager beers in the market.  As mass market beers became more dumbed down to increase their appeal to a wider and wider market, lager began to become synonymous with “bland” beer.  By trying to create a beer with as little “offensive” flavors as possible, breweries created a beer with little flavor.  But this certainly isn’t the fault of the poor lager yeast.  Fortunately, the United States is seeing a revival in craft lagers which is helping people learn the real heritage of this unfairly maligned fungus (and getting them in touch with some fine European lagers).

Final Words

So, Ales are beers that have been fermented with S. Cerevisiae; and lagers are beers that have been fermented with S. Patorianus.  Ale yeast likes working in warmer temperatures which allows them to ferment quickly while throwing off all kinds of fun by-products that give ales their classic flavors.  Lager yeast likes cold temperatures and creates beers that are crisper and cleaner in flavor.  In reality, beers produced from either yeast can be good or bad.  It’s all up to the brewer and brewery.

But wait! What about wild yeast?  Well, there are several more varieties of yeast that can be used in beer and even some bacteria as well.  Proceed immediately to my post, entitled: “The Yeasties, The Yeasties – The WILD Beasties in my Beer!

(For more information, check out “The Oxford Companion to Beer” edited by Garret Oliver, Oxford University Press ©2012. It’s a wonderful encyclopedia of beer knowledge that I used extensively in this post.)

8 thoughts on “The Yeasties, The Yeasties – The Beasties in my Beer!

  1. I’ve had people ask me the same question, and they sometimes seem surprised to learn there’s a real scientific reasoning behind the two distinctions. Not just some slight characteristic difference, or some line on a map. Well done.

Leave a Reply

Your email address will not be published. Required fields are marked *