Temperature swings and brewing

So this is not meant to be taken as a "new guy is afraid thread" more as a "new guy is curious and a search has not yielded anything" thread. Relax everyone, I'm not worried and I'm having a microbrew (from a brewery only 25 miles north of me that I just discovered after living here a year).

I'm assuming a constant fermenting temperature is ideal. I'm also assumign that having the fermenter temp change very gradually (as the surrounding air changes) would not shock the yeast. But how do temp swings affect the quality of the finished product? Do you risk the same off flavors as you do when just fermenting too hot or are temperature changes a whole new animal aside from just hot temps.

The kind of swing I am talking about is between 65-75 degrees F and I'm obviously brewing an ale.

you can use a bigger container to place your carboy or fermenter in; and then fill it with water - water takes temp changes better...meaning it holds temps more consistently.

If you think you're gonna be on the hot side; put a wet t-shirt on the fermenter with a fan blowing on it

Its not an issue of brewing hot. The current temp on the stick on thermometer is 70deg and for most of the time since sat night it has been between 68-70. The exceptions were when my thermostat went renegade and decided to heat our apartment to 80 degrees all night - then it jumped up to about 75 until I started sweating enough to wake up and open a window. With the window open the temp dropped down to about 64 and the heater decided it was sorry and did not kick on again.

Again, no worries and I'm sure the brew will come out fine. I'm just curious if anyone has experienced the same conditions and if there were any pronounced effects. I only ask because I'm curious now and don't want to have to wait a month for bottle conditioning to be complete and finally have my answer.

In short - you'll be fine.

I live in a place where we have extreme temperature swings. I try to keep the fermentation temps 70 or under for the ales, but sometimes a hot day or two will just jack up the house temp way above that.

You might sense some "off" flavors when you first taste the beer when it's green - but the flavors should mellow when it ages properly...

hope that helps...

post back and report...

Not sure if this helps, but on a side note, I just read that Duvel golden ale is fermented at 68 and the brewers slowly increase the temp to 84f until it's finished. So, it'll impart unique flavors but they are not necessarily negative.

Put the fermenter in a cooler with water in it. Add frozen 2 liter bottles of water as needed. If you make a foam lid to fit your fermenter it works even better.

I do lager primaries that way, with ales you usually don't even need the bottles, the water itself tends to equalize out the temperature.

Without looking up citations, my general understanding that temperature shifts of 10 degrees F will start shocking the yeast and slowing the process. Going to the high end of the yeast preferences will start producing off flavors, (esters, sulphur, basic things you don't want).
Lower just slows things down more.
Controlling the temp is easy with wet towels, Putting the fermenter into a larger container with water, ice, wet T-shirt/towel. Adding a Fan if the humidity is low really helps. You can do a search on "swamp coolers" for more information.
When you get paranoid about it, fermentation chambers, etc helps you control the temp, not just lower it. Not required until you want to make the best beer you can.

I wouldn't want this type of temperature swing to happen daily as I would imagine it would affect the finished beer but if you found it hot and lowered and kept the temp in the yeast range I don't think it would have a large impact.

In my experience fermentation temperature control is really important to making a quality beer.

mjn12 said:

But how do temp swings affect the quality of the finished product? I only ask because I'm curious now and don't want to have to wait a month for bottle conditioning to be complete and finally have my answer.

Click to expand...

IMO it depends a lot of factors and each situation can be different. One consideration is the range of temps you're dealing with...too cold and your yeast can shut down. Too warm and you have excessive esters, phenols w/ the possibility of diacetyl & fusels. If you're bouncing the yeast all over the place, your results can be unpredictable (if it doesn't just stall out).

Where is the yeast in the fermentation process? During the initial stages of fermentation, temp is more critical since this is where the bulk of those esters, phenols and fusels can be produced. During this part of the process, heat is actually being produced as a byproduct of fementation too. This relates to what jmo88 referred to where you initially ferment cool to minimize the ester & phenol production then gradually let the temp warm up so that the yeast can hit max attenuation.

The strain of yeast plays a role since different strains react differently to conditions. Yeast health and pitching rates prb also have a side effect too since unhealthy under-pitched yeast would likely be more susceptible to the effects of temp swings.

It seemed that the most active fermentation was during the first 24-36 hours after the yeast was pitched. I used the yeast that came with the kit (don't have the name right now). I rehydrated it per the instructions on the packet - lukewarm water (that had initially been boiled) for 14 minutes then pitched. There was visible (albeit small) bubbling in the yeast goo right before I pitched. The fermentation that occured didn't generate foam put putting your ear to the pail you could hear the bubbling. The temp was around 68 degrees at this time.

It was as fermentation was subsiding that the temp dropped to 63 (gradually as the apartment cooled). The heater went on and for 18 hours brought room temp back to 68-70 then later went renegade, bringing surrounding temp to 80, fermenter rose to 73 or so until someone caught the heater and room temp has stabilized around 68 for the past few days with very little bubbling from the air lock. Yeah I know bubbling isn't a sure fire indicator, but when it was practically percolating it was easy to see something was going on.

I'm just assuming fermentation happened as it should and taking my sg reading after its been in the primary for 10 days. Despite all temptation I'm not peeking in the pail until 10 days. Wish I had a better bottle so I could watch it all happen.

mjn12 said:

I'm just assuming fermentation happened as it should and taking my sg reading after its been in the primary for 10 days. Despite all temptation I'm not peeking in the pail until 10 days. Wish I had a better bottle so I could watch it all happen.

Click to expand...

Exactly!:fro:

You should be fine.

As a rule, you want consistant, comfortable temperatures for your yeast and if you're going to raise or lower the temp do it only a few degrees a day until you get to where you want to be (unless crash cooling). As mentioned above, too cold and it will shut down, too hot and you get weird flavors, to much flux and you get unpredictability. I share the opinion that good fermentation temp management is the single most improtant thing you can do to improve your beer and improve the repeatability of your recipes. That said...

It sounds like most of your fermentation was done so the most critical period had passed, which is good news. Also, your temp swings were all generally around ale ferm temps so I wouldn't expect anything real dynamic with your yeast. The short answer is that the heater going rogue wasn't ideal, but also isn't likely to effect your beer. Next time, rig up a water bath and wet shirt and admire your handiwork while knocking back a homebrew.

Gordie.

It seems to me that even with 5 to 10 degree temp. swings, it would take a longer time for 5 gallons of beer to change temp. In other words, if the beer was at 61 F overnight, and then the ambient temp. warmed up to say 67 F for the daytime, I don't think that the 5 gallons would warm all the way up to the 67 degrees all that quickly. So maybe the beer went from 61 F up to 65 F, but it doesn't seem like that big of a deal-especially at temps below 70 F (but at or above 60 F). Anyway, that's my $.02.

While I was brewing Holiday Cheer from Papazian's book I went ahead and took an sg measurement (since the thief was clean). At 7 days from pitching I'm at 1.023 for a recipe (http://www.crosby-baker.com/ipa.htm) which is supposed to have an F.G. of 1.014. Should I be concerned if this is where my brew stabilizes for the next two readings or should I just RDWHA(micro)B and bottle as long as its stable.

Waiting to bottle beyond ~12 days from pitching (this coming thurs) isn't so much of an option because I'll be gone for a while.

If you're concerned about your FG and potential bottle bombs, leave it in the primary. Chances are that it will sink slowly, a couple of points. If you're leaving for several weeks, I'd throw it in the secondary and wait for a slow fermentation to take it down a bit. Seven days is not necessarily time to bottle. Give it time for the yeasts to finish.

I won't bottle yet, 10 days was gonna be the soonest if the gravity was stabilized but I can push it a few more days, I don't really have a secondary - I do have a bottling bucket but I'm worried about the spigot leaking while I'm gone. If its still dropping by the time I leave then though, it'll just have to sit in the primary for 3.5 to 4 weeks - I know revvy commonly keeps his in the primary about this long.

Now if my holiday cheer would just cool enough for me to pitch the yeast. A wort chiller will be my next investment!