THE ACTUAL TRUTH ABOUT YEAST: Volume 3: Lager yeast, with Kevin Lane of Fermentis.

the world's most popular lager
yeast. Good ol' 34/70

Part 3 in our on going series about the little bugs we all love.  This time we are focused on lager yeast with Kevin Lane of Fermentis.  And this one is great.   In our next installment we will be talking all about sours.... yum!

What is lager yeast?  

Lager yeast is a yeast that is generally used for producing cool fermentations (to be discussed later).  It is often referred to as a bottom fermenting yeast, due to the fact that it ferments from the bottom of the tank rather than the top, as ale yeast does.  Lager beer is also, typically, stored cold (lagered) for a period of time before being packaged/sold to the consumer or consumed. 

The species itself, Saccharomyces pastorianus, is believed to be a descendent/hybrid of Saccharomyces eubayanus.  Lager yeast has been named multiple names in the past, most recentlySaccharomyces carlsbergenesis, after the Carlsberg brewery, but is now defunct nomenclature.   

What makes it different from ale yeast?

The easiest way to explain the difference (which isn’t easy at all) is that it is genetically different.  So much so, that it is categorized as a different species of yeast Saccharomyces pastorianus. The brewer typically doesn’t think about that when brewing, but that is the real difference.  The genetic difference influences the brewer to use lager yeast in cooler fermentations and for certain styles of beer, where you are looking (generally) for less flavor impact coming from the yeast.  Lager yeast strains are very similar to one another and do not produce as wide a flavor range as ale strains do (think English ales vs Belgian ales).  Typically, lager yeast will attenuate fairly well and produce a very clean, crisp beer.

What is meant by bottom cropping?

Bottom cropping is a term that has been created to explain the process of collecting the yeast from the bottom of the tank.  Since lager yeast ferment at the bottom, you have a higher likelihood that you will be collecting healthy yeast from the bottom.  This is not to say that you cannot do the same with ale yeast; you certainly can, you just run a higher risk of collecting less healthy yeast cultures.  In ale yeast re-pitching, brewers traditionally would top crop and collect the krausen.  Thus, when lager beer production really picked up… the brewers came up with a new term and a new way to collect.

Why can lager yeast perform at lower temperatures?

Why not?

… I am kidding. 

Lager yeast produce the flavors that the brewers want at lower temperatures because of the genetics.  It is difficult to explain because people have talked about the characteristics of the yeast as what they do for the brewer, not what they do as an organism.  I think I may have stated this before but I will repeat… yeast don’t ferment wort to make beer, they don’t ferment must to make wine and they don’t ferment apply juice to make hard cider nor do they ferment mash to make the base for distillates.  All that yeast is doing is attempting to survive and reproduce so that their genetics are passed on to their daughters and subsequent generations. 

So, to get back to your question, yeast perform (the way the brewer wants it to) in certain environmental conditions, simply because of the genetics

Will Lager yeast work at higher temperatures?

It depends.  Some of the strains will work at higher temperatures and others will struggle.  I guess the real answer is yes, they will.  But the more complete answer is, yes, they will but they may not successfully finish the fermentation and could produce some flavors that are unwanted. 

Some yeast strains are capable of the same fermentation characteristics at lager (low) and ale (high) temperatures.  There is a lot of research that Fermentis is currently involved with, to bring these answers to you more definitively.

So it will ferment, but it will put off some off flavors?

Yes, the yeast will ferment.  There is a higher possibility for the yeast to produce unwanted flavors.

What are the flavors produced by lager yeast?  

Lager yeast will produce a lot of the same flavors that ale strains will, just in lesser amounts.  Typically, lager yeast will produce the same ester profile as ale strains, just in low enough concentrations that humans either don’t detect it (below the flavor threshold) or just slightly detect it.  Typically, lager yeast are POF- (phenolic off flavor negative) and will not produce the flavor complexities that are common in some Belgian and German beers. 

Typical ester production would include ethyl acetate (apple), isoamyl actetate (banana), ethyl hexanoate (tropical fruit), etc.

 So it still produces esters, just different esters than ale yeast?

ester forms naturally in fermentation.

The difference in the ester production isn’t the molecules that the yeast are producing but rather the concentrations and ratios of one to the others.  This will develop the differing characteristics in the beers and in a way the styles that lager yeast is used in.  Due to the fact that esters are combinations of organic acids and alcohols, the elevated levels in ales could also be perceived as a harsher beer, compared to the delicate profile of lagers.

What causes lager yeast to produce more or less of these esters?

The best way to think about this is the principle of mass conservation: nothing can ever be created or destroyed. The reason I say that is the best way to think about it is because esters are produced from different alcohols and organic acids.  If the yeast is in cooler temperatures and there is a higher pitch rate (general characteristics of lager production), the yeast will be less stressed and thus produce less of the variety of alcohols and acids.  With less of the “building blocks” available, less of the esters will be produced.

So stress and temperature have an impact, but what about pitch rate?

Pitch rate can be thought of as another environmental condition, in a way.  If there is a higher concentration of cells in the wort at pitching, the yeast will be less stressed to reproduce to build the correct concentrations.  Essentially, all of the flavors and all of the characteristics of the yeast come back to stress levels. 

If a brewer wants to make extremely "clean" lager with very little ester, what advice would you give him or her?

There are a couple of things the brewer can do, but I don’t know the application ability.  There are a couple of things that are easy to apply to make beer more “clean”, as well.  The easy applications are lower temperatures and higher pitch rates.  If the brewer has temperature control and are able to ferment in the upper 40’s, the lager yeast will produce a very neutral flavor.  Likewise, the brewer can also pitch at elevated pitch rates, nearing 200g/hL or roughly 4 x 11.5g sachets of Fermentis lager yeast (some other producers have differing viability and pitch rates, so I can’t speak for them).

Practically speaking if you want to make lagers, you have
to be able to control fermentation temperatures. 

The difficult aspects to change about the fermentation would be to increase the back pressure on the fermenter.  This can be done with most any pressure release valves connected to the fermenters blow off port.  The other important thing to remember is you don’t want to build a “bomb”, so you need to make sure your fermenter is capable of holding back pressure.  Not easily done, but will increase the neutrality.

   

So practically, to make a great lager you need to ferment cold?

To make a great lager, it is strongly recommended to ferment cold.  It doesn’t mean that you can’t make a great lager at elevated temperatures, but it is much easier to do so at lower temps.  Yeast will act according to what you do to them.  If brewers know that lager type flavors are produced (or not produced) at lower temperatures, then I would suggest that you apply that to the lager fermentation.

Are there sugars that lager yeast can process that ale yeast cannot process?

No… well… it depends on what strains you are comparing.  Lager yeast typically will ferment maltotriose to near completion.  Some ale strains will ferment maltotriose to completion while others will hardly touch it, if at all.  The important thing for the brewer is to understand the capabilities of the yeast they are using and apply the correct environment to allow the yeast to produce the beer that the brewer wants.

 So wort composition is important?

Wort composition is always important.  I cannot say it enough, “Brewers don’t actually make beer.  They make wort.  Yeast make beer.  If yeast don’t have what they need, they won’t do what you expect.”

 What unwanted off flavors can lager yeast produce?   and how do you limit them?

The most common off flavors are sulfurs, meaty notes and other internal yeast component release.  Most of these are caused by time and temperature, but can also be caused by lack of nutrition, in some cases.  If you are attempting to make an American Light Lager (very difficult), there is a need to supplement nutrition for the adjunct addition.  Adjuncts will not bring any nutritional components other than carbohydrates (food).  Yeast will need the mineral and vitamin cocktail that malt brings to the table (plus a little Zn and Mn). 

What general advice would you give new and intermediate brewers about brewing a lager?

General advice: make mistakes and learn.  It is a much different practice brewing lagers and the best results come from paying complete attention to the brew.  Since I spent 5 years of my life as a Pilot Brewer at one of the big guys, I have a bit of experience with lager brewing.  I can say that it is a very difficult range of beer styles to master.  The fermentation is one aspect of it that, in particular, needs to be done right. 

home roasted grains .. lager... continued crazy from the kitchen

So I brew a lot.  I brew a lot with my brew crew, but we also all brew some on our own.   This brew day was on my own.  An all grain standard american lager with home roasted grains.   I have been reading recently on barleypopmaker's blog about roasting your own grains and about making specialty grains right at home.   It is a great read.   I have also been reading on makingbeerthehardway about malting.  But we are experiencing a richness of malt right now due in part to the support of BSG and Rahr.  So malting will have to wait for another day.   I want to encourage you again if you haven't checked out BSG, you should.  They are the premier wholesaler of products to your local home brew store.  But if you know what they carry you can encourage your local homebrew store to order it for you... and they carry everything.

So, back to home roasting grains.   I believe that fresh ingredients make a huge deal...kinda...  here is what I mean.   Fresher hops are always better, fresher specialty grains are always better,  fresher base malt... doesn't matter that much.  After all, kilning, and drying grains were originally methods of preserving grains.  They last for years, when properly stored.   Or so I have heard... I brew so much I wouldn't know.  a 50 lbs sack of grains lasts about 2 months around here.  inspired by barley pop maker I decided to follow his process for making golden roasted malt, I took .5 lbs of two row and paved it on a cookie sheet.  I put it in the oven for 20 minutes at 300 f.  The whole house smelled amazing.

No flavor or aroma can truly describe the snell.  Bread and nuts and roast.  Amazing. 

It should have been a 20 lovibond grain.  I thought it looked like 20.  But i was way off.  It had to be closer to 60 lovibond.    My oven must be a beast.   Because my standatd lager looks like a bock.  But I am undeterred, I will be roasting more grains myself. But I will add them to the mash differently, later in the mash to control color.   And I will be using an oven thermometer when I roast.     Making adjustments and learning is essential to getting better. 

I followed my standard brew in a bag with sparge rinse procedures.    I mashed at 152 for 60 minutes, then sparged to volume.  I then began the boil as normal. Added noble hops 3xs, chilled with 50 l ft of dual coil action. 


The brew came out way darker than anticipated.   So what to call it... it isn't technically high enough to be a bock, but it is clearly way way to dark to call a standard american lager.   So Im open to suggestions.

By the way, I hope you when you chill your stuff, you save as much of your water as you can.   I use the water from chilling to clean my gear.  To sanitize the fermenter,  to clean other brew gear. I'm not exactly a big environmentalist but... one planet, one chance...

Our Saturday Double Brew Session 8 hours of brewing fun...

8 hours is a long brew day.  If you have ever dreamed of being a professional brewer... try a double batch day.   Not a partigyle.  A true double batch day.   We have been double batching for a while now, in an effort to build up stock.  But with 16 gallons fermenting, I think we're in pretty good shape.  So next weekend a single 5.5 gallon batch of beer, partial mash style.   The team understands all grain.  Now I'm going to teach them a more reliable, and in my honest opinion, better method.

On saturday we were at it again. This time two beers, a standard american lager (just for learning about lagers) and another improv pale ale.   Each week I try to add another element to our brew day. These guys are beer fanatics.  I may have finally found my championship team.  And finally, after weeks of anticipation, Jake joined the team.   It was a welcome addition.   His pallet is excellent.   He can taste a beer and describe accurately what it needs to go to the next level.   With my experience, John's passion, MA's exotic beer knowledge and Jake's pallet I think some medals are in our future.   Who knows, a medal here, a medal there, a small microbrewery... then world domination and the fall of the MBC conglomerate...(insert maniacal laughter here).

We milled our own grains this week.  There was a slight snafu in terms of grain volumes, but fortunately we have plenty of grains, so we were able to adjust.  We grind our grist fine.   We set the mill gap to the size of a credit card.  Yes this creates some flour.  But we use a brew bag so we don't care.  I haven't had a stuck sparge in years.   If you're not using a brew bag, you need to be.   Even if you are a 3 vessel guy.  It completely eliminates the need for vorlauf.
And because you can grind your grain bill smaller, your efficiency will improve. Please don't argue about this point, it is so well established.  Physics is Physics everywhere in the known universe.  More surface are = more starch in contact with more enzymes more quickly...   You can see in the photo just how fine we mill the grains. On this day, in this kitchen... we hit 91.2% efficiency... yes 91.2%.

We were brewing on this day with RAHR 2 row base malt.   If you don't know RAHR they are a major producer of brewing malts.  A lot of guys think of Rahr as the affordable choice, but affordable does not mean lower quality.   I love 2 row base malt for general all purpose brewing.  It is incredibly consistent and extracts like a champion every time.   Special thanks to RAHR and BSG for their advice and support.  If you have any questions about malt, or brewing that you can't get answered locally.   Reach out to the maltsters, and suppliers.  You think you love beer?  These guys really love beer, and they are happy to help.

We followed our normal taste and test procedure for the mash.   Tasting occasionally and testing for conversion with iodine. When it passes the iodine test and tastes right, we're done with the mash.   If we need more melanoidal malty flavors, we remove some of the mash and we decoct... oooh fancy... not really. This is just the old school stuff we used to have to do to get the flavors we wanted.

When the mash was over we drained the bag, and Jake squeezed it like it owed him money.  Then off to the boil.   The hops?  all saaz.   So this will be an americanized version of a czech saaz lager.   (we didn't use pilsner malt).  We chilled, aerated like crazy (30 minutes with an aquarium pump) and we pitched rehydrated Fermentis 34/70, my workhorse lager yeast.

Temperatures are perfect in the garage right now for lagering.  The batch is holding steady at 52 F.   Should be a great clean, american lager.

Then like crazy fools... we did the entire process all over again...

REAL LAGER AT ALE TEMPERATURE - FERMENTIS 34/70 The Method, and 2 additional methods.

Crazy Weekend.  But Sunday, I found time to brew a batch of beer.  Just good ol simple beer.  Shooting for 1.032 post mash... Got 1.030, I'll take it.  Shooting for 1.042 post boil and nailed it. Small batch has slightly higher boil off rate percentage.

This Batch is a light american lager.   And that is a key you have to understand with lagers.  There are hundreds of lager yeasts.   Some attenuate out great, posting impressive 83% to even 88% attenuation.   But many, if not most lager yeasts feature fairly low apparent attenuation, in the home brew realm. So unlike an ale yeast that can handle huge OG. Many lager yeasts can not, they would leave the beer too sweet.  And that is not what you want from most lagers.  Certainly not what you want from a Light American Lager. (of course you can adjust your pitch rate to accommodate higher OG, I find attenuation has way more to do with the brewer and the pitch rate than the yeast) (NOTE: I am aware that commercial lagers under, commercial brewing conditions can and will attenuate out at avery high rate.  But most lager yeast, Saccharomyces pastorianus (( S.Carlsbergenus)) can not break apart one of the carbon links in a Maltotriose trisaccharide. )

This batch is pretty straight forward
2.25 gallon batch.
Water adjustments to get to 5.2 pH
4# lager malt
.3# carapils
.7# flaked rice (or minute rice)
Mash at 152 for 75 Minutes, no mash out (got about 72.3%) not bad
Hallertauer at 60,15,0 ... .33 oz.  each addition
Hard boil to break up proteins.
No Whirlfloc
Will use Gelatin to fine this before packaging.

And now for the shocker... I'm fermenting with Fermentis Saflager 34/70.  And I'm doing the primary fermentation at 65F.   After about 10 days I will move the fermentation vessel into the garage fridge at about 36 F for 3 to 5 weeks.
Now before you get all up in arms, and start firing me comments about how this will never work.  Take a breath and ask yourself the following questions.

1. Why not? Why in the world won't Saccharomyces pastorianus ferment at 65F?  What could possibly prevent this yeast from converting sugar to alcohol and carbon dioxide at this temperature?   What part of the metabolic transformation will be inhibited?  I think you know the answer is nothing.   It works fine I have been doing it for over 20 years.
2. Have you ever tried it? are you open to new techniques?  No this is not the classic, or even best way to make a lager.  But it works.  It works just fine.   
3. Have you confirmed your point of view with the yeast manufacturer?  I have.  I have had extensive conversations with Fermentis about this technique.  They say it should work fine. Fermentis is amazing to deal with, I encourage you to check out all of their yeasts.  
   

This is how lagering was invented.
Ferment as normal then store cold.

Now I know this isn't conventional,  But give it a shot.  All you need is a fermenter that can fit in your fridge, or even your keezer.   This is not at all what the Brulosopher did with his recent xbeeriment.  Where he displayed that you can ferment lagers at 66F and not even trained judges can tell the difference.   (And by the way if you're not reading and supporting Marshal's work, start now.  He is advancing home brewing.  So buy a dang Tshirt, we need his work to continue.)  Of course, you have to choose the right lager strain to pull this off.

This is a tried and true old school method for making a lager at home.  It is how we did it in the dark ages of home brewing.

Alternate method #1.  Choose a clean lager strain and just ferment the beer at ale temperatures.  It will be fine.   If you don't believe me read the Brulosophy post above.

Alternate method #2.   Ferment it at ale temperatures, and then lager it in the bottles or keg, cold for a month or two.  We used to call this bottle lagering.

It is Tuesday morning.  I brewed on Sunday.  There is a beautiful Krausen on the beer.   Cant wait to drink this one in 6 to 8 weeks. Wednesday morning nice 1/2" creamy lager krausen on the beer.

IMPORTANT NOTE.  AERATE YOUR LAGERS LIKE CRAZY