Ale character development in lager after packaging

[ntillemans]

I had a very clean Munich Helles. It tasted great upon transferring it to the secondary and then after lagering it for 1 month. I was proud of myself that I had produced a very good lager. But, now, just a few weeks after kegging, I'm picking up imperfections, which are becoming increasingly pronounced. Mainly, the characteristics that are coming to the fore are ones I would expect from an ale (not a lager).

I keep my kegged beer at 45F. I am diligent about sanitation; and I did a 3-day diacetyl rest at around 62F. I kept primary fermentation under 50F.

It seems to keep getting fruitier like an ale, but maybe slightly oxidized with slight/faint sherry notes...certainly inappropriate for a lager.

I produced a second Munich Helles...and am detecting similar flaws (subtle) at the time I was racking to the secondary (after a 3-day diacetyl rest at around 62F).

Where is the most likely hole in my process? Should I be purging the carboy/keg with CO2 prior to transfer (i.e, is it oxidation)? I'm not splashing into the carboy. Is it that touchy with lagers? Or is there something more glaring?

Thanks for your thoughts on this. I have a lot of control over my process. But lagers have been a real tease.

Nick

[hotrod38]

Next time you brew the Helles, try pitching the yeast at 46F and holding the temp at 48F...Let this go for 2-3 weeks or when you have reached terminal gravity. Skip the D rest and go straight to the keg and lager it for 4-6 weeks at 34F... I do this and never have off flavors.

[Elbone]

Should I be purging the carboy/keg with CO2 prior to transfer?

Absolutely! Any exposure to oxygen after primary fermentation is bad. Eliminate all you can. Also- do you completely disassemble your kegs for cleaning/sanitizing between every filling? I had a few sanitation issues before I started doing this.

[Crackin]

I have been struggling with the exact same problem. Some of my lagers have a fruity ester flavor, while some are perfect. After much troubleshooting, I think I have narrowed it down to not pitching enought yeast. Every time I "overpitch" they turn out great. When I try to pitch the "correct" amount, they have some fruitiness. I have found that usually, those fruity ester flavors dissapear with more cold storage time, between 1 and 4 months. I have messed around with diffenrent amounts of O2 for fermentation, but, although maybe related, I don't think this was causing the problem.

[ntillemans]

Thanks for your advice.

I do pitch a 4L starter which I step up from 1L to 4L. I understand this should provide more than enough yeast...but, THEN, how big are your starters for your 5 Gal batches? Are they bigger than THAT?

I do take the keg apart and put it back together again after sanitizing the parts. So, I really don't think it's sanitation, though I did just clean my gas lines today.

I think oxidation is a possible problem. Ales have been very forgiving...but maybe lagers, not so much. So, I might be more careful with lagers.

I do understand that doing a diacetyl rest at a temp that's too high for too long can produce esters. But I didn't think 60F for 2-3 days would cause much of a problem. Everything I've read so far has indicated that would be okay. And it didn't cause any problems in the first lager, only after kegging....

I do let the beer sit in the primary for 2 weeks plus. I don't want ale notes...but diacectyl is worse. Maybe letting it sit in the primary for 4 weeks would be a good thing.I've heard that a diacetyl rest could be avoided altogether with adequate patience. But, then, I've heard it could be problematic for a diacetyl rest if you wait too long.

I'VE had miserable buttery beer, which I think is worse than the problems I'm having now. So diacetyl rest or more time in the primary with no rest? Which is best?

Thanks again.

[ntillemans]

I got some firsthand feedback from a couple of senior MHBA members who sampled it. Guess I'm picking up on residual sweetness; and I should have mashed at a lower temp. Neither thought it had anything to do with fermentation.

Guess my suspicions were wrong.

Thanks for your advice.

Good to take all these factors into account regardless.

It all helps.

Thanks again,

Nick

[ajdelange]

Esters (fruity flavors) are formed primarily when the yeast are in growth phase and at higher temperatures. Thus to keep them at bay in a lager you pitch lots and lots of yeast and supply them with a good bit of oxygen. There are 2 rules of thumb. One says 1 million cells per mL per °P. To tell whether you hit this or not you obviously need a cytometer and microscope. The other is to pitch a 10% starter (half a gallon in a 5 gallon batch). Obviously you want to use a lager strain. To minimize formation of esters (and fusels) pitch cold and ferment cold (in the 40's). The starter needs to have been properly managed (i.e. supplied with nutrient as the extracts from which most of us make starters are notoriously low in FAN and given plenty of oxygen. Properly managed a diacetyl rest should not be necessary but you do need to be sure that yeast go into the lagering vessel as diacetyl will be formed by oxidation of residual acetolactate in the beer and you want yeast there to vacuum this up. Note that we said "oxidation of residual...". It is essential to protect the beer from oxygen once it goes to the "package" be that keg or bottle for this reason. Oxygen also produces other staling flavors like wet cardboard, sherry, vinous....