fermentation temperature

[Robert W Leicht]

After active fermentation stops, is it necessary to maintain constant temperature for the balance of fermentation time (one month)?

 

[Jag75]

Depends on what your brewing . Lager or an Ale. If your doing an Ale it's best to ferment at certain temp and hold that temp for roughly 5 days . Then you can let it come up to room temp (70f) for clean up

 

[thehaze]

I don't think any beers would benefit from sitting in the fermenter for a month ( except specific styles that require a longer time - Brett, mixed, wild, sour, etc. ). The bulk of fermentation - where esters, phenols, off-flavours will be created - would be over in 3-7 days for any yeast. Some yeast require a diacetyl rest, so you will need to raise the temp. and hold for a few days, in order for the yeast to finish and possible clean after itself. Sulphur - some yeast produce it during fermentation - can also dissipate with time, so in the end it varies how long each beer needs to sit in the fermenter, but one month is too long. Raising the temp. after fermentation will not harm your beer.

 

[pc_trott]

Some yeast require a diacetyl rest, so you will need to raise the temp. and hold for a few days, in order for the yeast to finish and possible clean after itself.

As a rank newb, I'm wondering; do only some yeasts require the diacetyl rest? Has anyone put together a list of which ones do?

 

[OnePlate]

As a rank newb, I'm wondering; do only some yeasts require the diacetyl rest? Has anyone put together a list of which ones do?

I know White Labs and Wyeast both add notes to yeast descriptions when they need a good diacetyl rest but for most traditional strains of yeast a short rest is commonly used. Kveik strains as a whole do not usually produce any diacetyl or much else and don't usually need the same resting time.

 

[ReaperOnefour]

If you are brewing a lager yes. For an ale no. I usually pitch between 67-69 degrees. I use US-05 95% of the time. During fermentation the temp usually shoots up to between 71-73. I keep my fermenter in the hall bathtub. ( the coolest room in the house) After fermentation i just let it sit. The temp usually drops to around 68-70. ( depending on ambient temp.) I've never had any problems with this method.

 

[RM-MN]

I don't think any beers would benefit from sitting in the fermenter for a month ( except specific styles that require a longer time - Brett, mixed, wild, sour, etc. ). The bulk of fermentation - where esters, phenols, off-flavours will be created - would be over in 3-7 days for any yeast. Some yeast require a diacetyl rest, so you will need to raise the temp. and hold for a few days, in order for the yeast to finish and possible clean after itself. Sulphur - some yeast produce it during fermentation - can also dissipate with time, so in the end it varies how long each beer needs to sit in the fermenter, but one month is too long. Raising the temp. after fermentation will not harm your beer.

Most beers benefit from being in the fermenter for a month. Much more yeast and trub settle out and the beer starts to mature there. Keep the airlock filled and the fermenter closed. The only beers that do not benefit from the longer time are those that are intended to be drunk young and IPA's where they lose their aroma. Try a few, you'll see.

 

[TurnipGreen]

If you plan on keeping you beer in the primary for an extra month a constant temp is important. From my experience, it’s more about keeping oxygen out of the fermenter more than any thing. When the beer warms up and expands it pushes co2 our of your fermenter and when it chills and contracts is sucks air (with oxygen) back in. The the oxygen make your beer taste like a wet cardboard box.

 

[KookyBrewsky]

I've bottled all my beers after 3 weeks in primary. I have no intentions of doing secondary. I live in Florida where it's always hot; I have a large storage tub with a small layer of water on the bottom and holes cut in the top to fit two fermenters. Then I just place cold items in the water and wrap the fermenter in a cold towel. After 5 days or so I just take it out and leave it at room temperature (74*F) here and don't bother it. On bottling day I test gravity and taste it before adding the priming sugar. I did taste it once after adding the sugar and it's quite funky.

During fermentation, it inevitably fluctuates depending on activity. It averages often at 70*F but I've seen it at 67*F and the towel wrapped around it up to 72*F. I think after 5 days, room temperature from 70-75*F should be fine based on what I've ready, leaving it there for however long you feel. But... I can't even taste the first beer I ever brewed for about another week and a half... Some sort of fermentation chamber is next on my list. I want to be able to brew lagers and maintain a steady temp for the yeasty bois. I've tasted them all before bottling and so far, none have skunked, they've all been perfectly tasty, green, flat beers.

 

[Nubiwan]

I ferment in my basement which is around 60 degrees in winter and a tropical 68 in summer. Temps stay reasonably steady. My latest Irish Cream and Amber Ales were both pitched around 58 degrees. I did put my yeast in a warm starter for 10 minutes. They both took off, bubbling within 12 - 20 hours. They will be at FG in 5 days I reckon. Got to dry hop my Amber. Will bottle in 10.

Point is, I do nothing to affect temperature while pitching and I've never had an issue. I might cold crash or rest (heat up) a batch, when complete, or near complete, but since I don't keep accurate notes, I will never know the difference. All my beer has been top notch imho.

As opposed to evidence suggested many times on here, I have never seen my ferment temps higher than my room temps. Both my current batches sit at 60 degrees. Room temp.

 

[eric19312]

If you plan on keeping you beer in the primary for an extra month a constant temp is important. From my experience, it’s more about keeping oxygen out of the fermenter more than any thing. When the beer warms up and expands it pushes co2 our of your fermenter and when it chills and contracts is sucks air (with oxygen) back in. The the oxygen make your beer taste like a wet cardboard box.

This is good to consider. Partly depends on your head space and the amount of temperature fluctuation. As head space warms the gas expands and it will blow out some gas from the headspace. If the gas in the headspace then cools back down it will contract, and pull air in through your air lock.

In addition, at end of fermentation your beer has some CO2 dissolved in the beer. Right after end of active fermentation there is actually quite a bit of CO2 dissolved in the beer. Some of this will come out of solution over time, into the headspace. If the beer warms up, even for s short time, even more CO2 comes out of solution. You know this because priming sugar calculators use this "highest temperature after fermentation was complete" to estimate how much CO2 is still in solution.

Small temperature fluctuations are not a big deal, if you are keeping the fermentor in a room that changes 2-3 degrees (I am guessing) the impact is probably very small. But if say you are using a smart thermostat in that room and driving big temperature swings for different times of day (I do that cause I like to sleep in cold house but like it comfortable during the day) and you have a decent sized headspace in the fermentor (worst case might be a plastic bucket) you could likely be pulling in significant amount of air every temperature cycle. Its why the whole secondary fermentor idea which I think came to brewing via the wine making guys has you start fermentation in a container with a large headspace and then transfer to smaller container with near zero headspace for secondary (I still have several 5 gallon glass carboys I used for this purpose many batches ago). My family are home winemakers and they always secondary and always top up their secondaries with finished bottled wine up into the neck of the secondary carboy (other wine makers use sanitized marbles for this purpose). The wine is degassed at this point so no gas coming out of solution and with almost no headspace almost no expansion/contraction of the headspace due to temperature changes.

 

[LittleRiver]

It's easy to rig a balloon to take care of the suck back issue. Here's how I did mine. I got the little elbow fittings from Ace Hardware, the tubing clamp came from a nurse friend.

If you bottle, route the second hose into a jar of Starsan, like this:


If you keg, route the hose to the beer post of your empty keg, and put an airlock on the gas post. Fermentation gas will purge the keg.


When the beer is ready, do a gravity powered closed transfer by connecting the fermenter spigot to the keg beer post, and the gas post to the top of the fermenter. I use this filter on the beer line to catch trub.


Keep the clamp going to the balloon closed for the first day or two of fermentation. This gives the yeast time to purge the fermenter headspace. You want the balloon to fill with fermentation gas, not the air that is initially in the headspace. Once you open the clamp, leave it open. During cold crashing (or temp swings during bulk aging) gas will be pulled from the balloon as needed.

Use a mylar balloon with a volume of 1-2 litres. Don't use an elastic balloon. They're oxygen permeable, and if you need to briefly open the fermenter to drop in additions, you don't want the balloon to deflate.

 

[ncbrewer]

I'm probably over thinking it, but I try to keep the temp pretty constant so the yeast stays in suspension as long as possible. I figure letting it cool a little might get the yeast to floc out sooner, and I want it to keep fermenting until it's really finished. Also to clean up any undesirable compounds. Depending on the season, I find a temperature that I can maintain and keep it there. Like I said - probably over thinking it.