Temp fluctuations during lagering?

[Asta]

I just put an Oktoberfest in to lager at 36F (as cold as my fridge will get). I plan on keeping it there for as long as I can stand it, maybe six months. In the meantime, I don't want to be without my fridge which I want to use for other brews.

So the question is whether there is any downside to allowing the lager temp to fluctuate over time? I can put the carboy outside or a cold place in the house, where the temp might go as high as 50F and remain there for a couple weeks before I can get it back in the fridge at 36F.

I can't imagine this will enliven the yeast since fermentation was done prior to dropping it to lager temps.

Will this cause any off flavors?

 

[duboman]

Well, my first question is why would you lager an Oktoberfest for 6 months? Not sure of your recipe but my Oktoberfest lagers for about 5-6 weeks. I'm not saying you can't lager for 6 months, I just don't think it's necessary.

Maybe that will help you decide

Ideally once the beer is lagering near freezing you keep it there until you are ready to package.

 

[Asta]

I believe Oktoberfests were traditionally lagered from March to October.

 

[duboman]

I believe Oktoberfests were traditionally lagered from March to October.

Yes but keep in mind that was before the days of technology and temperature control, today we have refrigeration, back then they brewed by season and took advantage of nature's temp swings and cellaring

 

[Asta]

Let's assume I want to do this beer the old fashioned way, what sort of temp variation is permissible during lagering?

 

[duboman]

Let's assume I want to do this beer the old fashioned way, what sort of temp variation is permissible during lagering?

I would suggest a range of 35-40 degrees as acceptable

 

[ajdelange]

You can make a passable lager in a couple weeks by using techniques like the diacetyl rest or you can do them the traditional way without a diacetyl rest and long lagering. Which do you think makes a better beer? I'll leave that to the individual reader to decide but as you can't buy beers made in the traditional way any more (that I know of) you'll have to brew some in the traditional way if you want to be able to answer the question. SWMBO takes me off to Canada for the summer every year so I brew a batch in May and it sits in the cooler until late October. When I get back the beer is well lagered. No doubt about that. And its pretty good too. If I didn't have this lagering period imposed would I wait 5 mos? No, I wouldn't because the beer is pretty good after about 8 weeks (but it keeps getting better for a year and a bit more).

Philosophy aside, the man asked about allowable temperature variations. I really can't answer that question but given that the best beers are (were) lagered for extended periods at temperatures as close to freezing as could be attained we might conclude that perhaps the key consideration is keeping the beer cold or, put another way, the fact that the temperature varies somewhat may not be so important as that it is kept as low as possible for as long as possible. Back when PU was made in the traditional way we would occasionally order a keg of same. Some kegs were definitely noticeably better than others and, rightly or wrongly, I attributed that to how the kegs were treated between Plzen and chez moi.

 

[m00ps]

I'm not sure why you would want to lager for that long...I don't think you'd see any difference between 6-8 weeks and 6 months. All it would do is tie up another fermentor from making more delicious beer.

But I would guess as the beer gets older, temperature variations are much less harmful to it. Considering you can have temperature swings near the end of primary fermentation without much effect, I'm guessing it could swing up to the 50s for lagering without any noticeable effect on flavor. It's just dropping out particulate matter, so going warmer will only make it take more time

 

[ajdelange]

I'm not sure why you would want to lager for that long...

As I noted in my post if I want beer to be available to me when I get home in the fall I have to make it in the spring.

I don't think you'd see any difference between 6-8 weeks and 6 months.

Ah, but you do see change and pretty dramatic change too. Lager beer has a life cycle and a long one too. Just to give you an example in comparing pils made with Weyermanns floor malt and Weyermanns pneumatic malt the beer made with the former is much better than the beer made with the latter when the beers are young - i.e. younger than the full lagering period of 3 mos. Then they begin to change places. At the end of 6 months the floor pils is the better beer. Both of them hang in there for over a year. I am currently enjoying the last of a Vienna I brewed a year and a half ago. It is very, very smooth.

All it would do is tie up another fermentor from making more delicious beer.

Yes, I would if you lagered in your fermenter which is why you don't do that. I lager in Sanke kegs. Part of the secret of the long, long 'shelf' life is that the beer is on the yeast the whole time. This relates, I suppose, to the temperature discussion. Cold storage on the yeast keeps them just alive but metabolizing so slowly that the energy sources available to them in the finished beer prolongs the life span. They don't die and they don't, therefore, autolyze. They are able to keep the beer in the reduced state so that diacetyl never becomes a problem. It is interesting to note in this regard that as two years are approached and the yeast are finally giving up the ghost the diacetyl does begin to creep up a bit. That is the signal that one ought to finish off the batch. I don't mean to imply that the diacetyl is objectionable at this point by any means. It's at the synergism with caramel flavors level. If I kept it still longer I doubt the diacetyl would increase much more because there can't be much acetolactate left in beer this old.

But I would guess as the beer gets older, temperature variations are much less harmful to it. Considering you can have temperature swings near the end of primary fermentation without much effect, I'm guessing it could swing up to the 50s for lagering without any noticeable effect on flavor. It's just dropping out particulate matter, so going warmer will only make it take more time

There is a lot more that goes on during lagering than just dropping out particulate matter! See Noonan or some other text. I expect that if cold were not an important part of producing the best beer people would not bother to hold it cold. Certainly lagered beer can tolerate some temperature increase or it would be impossible to get it from brewery to consumer but I think it is also pretty clear that the colder the distribution system keeps it the more enjoyable the product turns out to be. You ought to be able to do some simple experiments in which you buy some fresh beer and store half of it warm and half of it cold and then compare (after attemperating both to serving temperature). The QC departments of breweries often do exactly this in order to detect problems in the stability of their beers.

There is no question that higher temperatures accelerate degradation of finished beer and thus presumably also finishing (lagering) beers. Beer lagered at a constant 33 °F is going to be better than beer that is allowed to rise to 50 even for a few days. But is it going to be that much better? That's what the guy wants to know and I can't answer that question.

 

[duboman]

Aj, thanks for the great insight