Banana in my Pilsner?

[jonheather2010]

Hello all,

First post here. Brewed a Bohemian style Pilsner using Weyerman’s floor malted Bohemian pilsner malt recently and am a little disappointed to find a detectable amount of banana-like esters (also possibly DMS… I don’t think I’m very adept yet at picking out DMS) nearly 3 weeks into lagering. I pitched a pretty healthy amount of yeast into fermentation (probably could’ve been a bit bigger) and fermented at about 50-52 degrees (yeast used was WLP802). I let it go through a diacetyl rest for about 2 days when it was 2 Plato away from FG. OG was 1.050 and FG ended up at 1.012 (expected was 1.010). I’m trying to figure out what might have gone wrong. My theories:

1. I boiled pretty vigorously for 60 minutes. I’ve read that it's common to do 90 minutes or more… maybe the DMS prone pilsner malt should’ve been boiled longer?

2. I pitched the yeast in the low 50’s, but accidentally let the wort drop to the low 40’s overnight before correcting the set temp on my temperature controller. The temp slowly climbed to the high 40’s over the next day and fermentation began within less than 48 hours. Could the cooling to the very low 40’s after pitching flocculated some of the yeast and caused a pseudo-underpitching? I know that underpitching could contribute to diacetyl but could it also cause my issue?

3. I raised the temp to about 66-68 during the diacetyl rest, but was this temp to high? The rise was also pretty quick… less than 18 hours…. and the SG was still at 1.018 when I raised the temp. Could any of these factors have coaxed the yeast into producing a lot more esters? Should I have started the diacetyl rest when I was closer to FG and rested at a lower temp (say 60 degrees)?

4. Could the slight under-attenuation (1.012 instead of 1.010) be responsible for any of this?


Input is appreciated. Thanks!

 

[friarsmith]

Here are some thoughts related to each number in your post:

1: 75-90 mins is probably best practice w/ pils malt as it contains a lot of DMS precursor. I use Wey Bo Pils & Best Malz Pils for most of my lagers. Anything less than 75 min vigorous boil usually results in some detectable corn/peas DMS aroma, in my experience. Especially in a pale lager. I've also noted (after prompting from judges) some sweet nougat-like flavor/aroma from Bo Pils (esp w/ a decoction mash), so maybe you're mistaking this desirable sweet and bready malty aroma for banana... just a thought.

2: Well done for pitching in the low-50's. I wouldn't stress too much about the "low 40's" temp. It's likely the wort was a bit warmer than your ferm chamber thermostat setting anyway. Potential underpitching is a bigger issue, however. How many cells (roughly) went into your 1.050 wort?

3: D-Rest ideally should be 6-10* above fermentation temp. Sounds like your timing in terms of attenuation was ok, but perhaps a bit too warm for the D-rest.

Let's talk about an easy fix... Assuming the beer is in secondary in "lager mode," you might consider pitching an actively fermenting half-liter yeast starter into the vessel and let it sit around 50* for a few weeks. Then crash cool for a few days and rack to a keg or bottling bucket. This "krausening" technique should clean up the beer and resolve many of the issues.

Lagers are all about process and patience and it sounds like you are on the right track, so take heart. Once you've heard the siren song of the lager, you never go back

 

[passedpawn]

I made a pilsener that had banana in it. I made it mostly the same way I've always made pilseners (I make them often). I used a yeast (not my favorite) that I use a lot, W34/70. Because it's such a familiar process, and the ingredients are all familiar, I conclude that the flavor must have come from some sort of infection. No idea. I've made the same beer since, with that yeast, without any issue.

 

[jonheather2010]

Thanks so much for the input! I cant remember exactly how many cells... it was in the 350 billion range for a 5 gal batch that ended up being just over 4. I did do a single decoction on this so it is very possible that some of the flavors I'm getting are expected.... maybe what's throwing me off is I was expecting a super clean beer, where as I've read that Czech pilsners specifically are not usually as super crisp and tight as their German cousins. I'll probably implement all of your suggestions next time and see what that gives me. Thanks again!

 

[friarsmith]

FWIW, 34/70 is the Weihenstephan strain from Bavaria. I had one of their pilsners a few months ago and tasted very subtle banana-- almost to the point where I did a double-take on the six pack carton and bottle label to be sure I hadn't picked up their hefe by mistake. Perhaps under certain conditions it throws some ester that is reminiscent of banana. And that Bo Pils definitely gives some sweet nougat which might (when combined w/ other factors) come across sweet, like banana.

I brew w/ 34/70 a lot and it definitely brings out more malt character (vs hops), but I have never gotten any banana. I also really like WLP850 for German or generic pilsners when crispness and hops are desired.

I'm still working on two kegs of German Pils from a split 10 gallon batch (Jever-ish clone) between 34/70 and WLP850. They are very, very different beers but each delicious in their own way. The 850 batch was clear, clean and ready to drink around day 40 with very prominent hops. The 34/70 batch needed 3 more weeks to fully clear out (even w/ gelatin) and certainly was more balanced or malt-fwd.

 

[passedpawn]

Thanks so much for the input! I cant remember exactly how many cells... it was in the 350 billion range for a 5 gal batch that ended up being just over 4. I did do a single decoction on this so it is very possible that some of the flavors I'm getting are expected.... maybe what's throwing me off is I was expecting a super clean beer, where as I've read that Czech pilsners specifically are not usually as super crisp and tight as their German cousins. I'll probably implement all of your suggestions next time and see what that gives me. Thanks again!

I've been working at making the perfect CRISP german pilsener for years. Here's a few hints (I think I've got it down). I'm drinking a glass right now

• Pitch yeast at cold temps (50F), and hold them for 2 weeks. After 2 weeks, I raise it up to 60F to make sure it finishes completely. Don't worry if it takes 3 or 4 days to see signs of fermentation.
• Pitch lots of yeast. Starter, or 2 packets of dry, rehydrated.
• Keep the OG LOW!!! I keep my OG under 1.050. This is critical.
• Mash under 150F for at least an hour. 90m is even better (you'll get a couple extra points of attenuation from yeast).
• Only pilsener malt. Nothing else except the hops. After trying all nobles, I prefer tettnang.
• Cold crash and use gelatin, if possible. Kegging preferred. Yeast stays in suspension for a long time, and it has a flavor that you don't want in a pilsener. If you bottle, make sure to refrigerate your bottles for days before drinking, and pour carefully.
• If you keg, consider filtering. It's a hassle, and I rarely do it, but man you can really strip the beer of all suspended particles and make a stellar pilsener this way. I use a plate filter with 5um filters.

 

[passedpawn]

FWIW, 34/70 is the Weihenstephan strain from Bavaria. I had one of their pilsners a few months ago and tasted very subtle banana-- almost to the point where I did a double-take on the six pack carton and bottle label to be sure I hadn't picked up their hefe by mistake. Perhaps under certain conditions it throws some ester that is reminiscent of banana. And that Bo Pils definitely gives some sweet nougat which might (when combined w/ other factors) come across as banana.

I brew w/ 34/70 a lot and it definitely brings out more malt character (vs hops), but I have never gotten any banana. I also really like WLP850 for German or generic pilsners when crispness and hops are desired.

I'm still working on two kegs of German Pils from a split 10 gallon batch between 34/70 and WLP850. They are very, very different beers but each delicious in their own way.

I only use Wyeast Munich Lager (can't remember the number) for my pilseners now.

 

[schematix]

I practice the low oxygen procedure on my pretty much all my beers now. One of the suggested processes is to only do a gentle boil for no more than 60 minutes. I've done it many times now, and there is 0 detectable DMS so i wouldn't go down that route.

You may need to wait longer. I find lagers take minimum 4 weeks from pitching before the flavor is cleaned up enough, and 6-8 weeks is usually where they peak.