Underpitching lager yeast, what can go wrong?

[BruceBrews]

Yesterday i brewed my first ever lager, I'ts a maibock and I got an OG of 1.070. Prior to brewday I made a 2l yeast starter and I used one smack pack of wyest 2124 (bohemian lager). Only 5-6 hours after pitching the airlock had activity.
Now I have read that when makeing a lager you need to double the amount of yeast than when makeing an ale, but i went with my normal procedure.
What are the signs and symptoms of underpitching? The fermentation took right off, so did I dodge a bullet here, or do I still need to worry?

I pitched at 65f and plan to go down to 50 in two days, is that how you are supposed to do it, or do you ferment it cold form the beginning?

Cheers!

 

[McKnuckle]

You should ideally be fermenting cool from the beginning. At the very least, if one does pitch warm as you did, place the fermenter in a space with ambient temps in the 46-52F range (or control the wort temp directly). You may be able to limit esters if you chill it quickly, but don't wait two days, or you'll be past the prime opportunity for that.

Regarding yeast count, empirically it would seem that you pitched enough, judging by the short lag time.

 

[BruceBrews]

Ok, thanks.

I just took the advice from this artcile https://www.homebrewtalk.com/lagering-101-need-know-making-lagers.html , where it says to keep it 2 days at 65f, but i started to cool it down already. My plan is to cool it to 60f first and then down to 50f, probably over the coming night.

 

[Cavpilot2000]

If you can, get yourself a packet or two of a dry lager yeast like 34/70. Have it on hand in case your fermentation stalls, which is entirely possible if you are lowering your temp that quickly. I'm not saying you shouldn't lower it that quickly (ideally it should have never started that high to begin with) - you should, but it may shock the yeast into dormancy. If you experience that, just pour the pack of dry yeast right on top, close the fermenter back up and drive on.

There are people who do warm-fermented "lagers", and the guy who wrote that article seems to be taking a hybrid approach, but his whole fermentation profile is very contradictory to standard lager practices. The time spent at 65 degrees is going to create esters, which is exactly the opposite of what you want with a lager. Most people ferment their ales in that range (65-70).

Basically what he is describing is making a cold-fermented ale. It won't be terrible, and, in fact may be an excellent beer, but you may get a stalled fermentation, and you will likely have some degree of ester and diacetyl production with all that warm time.

But ride it out and see how it goes (just get yourself that dry yeast and keep it on hand - it could save your beer). ONly time will tell.

 

[dmtaylor]

If the yeast is very fresh, and fermentation takes off quickly within a few hours like it did for you, then there's not a great problem in "underpitching". Pitching additional yeast when starting out at relatively cooler temperatures is advisable for insurance. You'll know it's underpitched if it takes more than like 24 hours to take off. Potential effects of underpitching lagers include acetaldehyde (tastes like apple or latex) or contamination by wild beasts, increased sulfur and esters -- all sorts of stuff you don't want at all in a lager.

In this specific case, I think you'll be alright. But in future, as others have suggested, you should consider pitching larger starters, and starting at colder temperatures.

 

[Bassman2003]

Lagers have a lot of stigma around them but not too much to fear imho. Colder temos just slow the yeast down. So the proven methods are to pitch a lot of yeast to overcome the slow activity. This is with the goal of not having your beer in the primary fermenter for an extended period of time. This might be from a commercial point of view (move the beer on to make space for the next batch) or from a general it is better to get things over with as nothing good happens after midnight...

I agree that short lag is a big goal and you accomplished that. I often buy one pack of yeast, make a 2L starter at 50f than add another 2L, chill down lower, siphon away the wort and pitch. This usually gets me to transferring to a spunding keg in 5-7 days with a 48f ferment.

Bryan over at Low Oxygen Brewing makes a lot of lagers and he buys 5 packs at a time with a re-pitch approach that allows him to finish fermentation in 3-5 days. His approach really pitches a lot of yeast which allows for the suckers to really gang up on the wort and mow through it. Minimizing yeast stress and producing super clean flavors.

 

[McKnuckle]

The HBT article you linked to is interesting and not without merit, but have a look at some of the comments for a better perspective. Even a couple of the first ones:

1. Kharnynb on July 23rd, 2017 - 4:16pm
   while this is a way to make lager, a lot of these steps are not always needed to make good lager, starting colder and keeping a constant temperature will remove most steps including diacetyl rest or even cold crashing…
   
   
2. wobdee on July 24th, 2017 - 2:06pm
   I find my Lagers are much more crisp and clean tasting if I pitch a lot of yeast and ferment cold, less than 50°. Also haven’t seen a need for diacetyl rest with proper pitch rate. Only takes 8-9 days for my Lagers to reach FG then I drop a couple degrees per day, keg by day 14 then lager for 6 weeks.

And on it goes, worth reading.