Importance of maintaining wort temperature

[yoboseyo]

From all I've heard temperature control is everything, but what are the actual effects temperature fluctuation within the recommended range of the yeast?

I left the fermenter at a constant ambient temperature of 18C after pitching the yeast at 21C. Now the wort has gone up to 21C 40 hours into the primary. I'm not sure what temperature the wort cooled down to before the fermentation went active, but should I be trying to cool the wort to counteract the wort heating itself due to yeast activity?

If so, what's the best way of doing this? I don't have a fridge or anything fanciful. I can put it in a colder place for the next day or two and keep and eye on the wort temperature. What temperature do you think the wort will reach at its peak?

BTW I'm using US-05 that I pitched dry. First signs of fermentation was after 20 hours.

 

[Alex.Tas]

Not all commercial breweries can heat their fermenters effectively to get to a certain ferment temperature. They use big heat exchangers (such as plate chillers) to cool the wort down post boil, which gets them to thier target pitch temperature.
The fermenting vats may have a "jacket" which is effectively a second skin around the fermenter, with a space between the fermenter wall and the outside of the jacket. They can pump cold water, or really cold water through this jacket to chill the beer from the outside, to counteract the exothermic nature of sugar digestion by the yeast. These bigger brewies actually rely solely on the yeast to generate the heat they need to maintain the ideal temperature for their fermentation profile.

So there are many ways you can keep the wort cold enough during the fermentation stage. you can replicate this on a small scale via a number of ways.
Putting the fermenter in a cupboard is a good start, as it will insulate to some degree. You can:

• use frozen PET bottles either strapped to the fermenter
• add ice/frozen PET bottles added to a water bath around the fermenter
• stick the fermenter in a larger bucket (those flexible tubs from bunnings would work), half fill the bucket with water then drape a wet towel over the fermenter. make sure the towel is partly submerged in the water still
• Move the fermenter to a cooler part of the house
• sit it on a concrete floor

heaps of ways to skin a cat.

What are some of the negative effects you can get form swings in temperature?

1. inconsistent results - one batch may taste great, another batch made to the same recipe fermented at a different temperature may taste awful (usually too high)
2. fusel alcohol production at higher ferment temps (give you a nasty headache and beer tastes rubbish)
3. changing ester and other byproduct production (sulphur, acetaldehyde, diacetyl just to name a couple)
4. loads more,

Difficult to say what the max temp will be sorry. but I'm not too surprised to see it jump the 3° you mention.

 

[GalBrew]

The best way is to get a fridge or freezer, temp controller and heat belt.

 

[Yob]

Get a fridge.. An stc or similar and never have to **** about or worry again.

 

[yoboseyo]

I dropped the wort temperature to 19C and I'll try to keep it between 19-20 for the rest of active fermentation. I hope the quick 2C drop didn't shock the yeast too much

 

[Benn]

Beersmith Podcast #128 (most recent)
https://itunes.apple.com/au/podcast/beersmith-home-beer-brewing/id398500515?mt=2&i=371470525
John Palmer puts into layman's terms some of the intricacies of fermentation. Worth a listen for the novice to intermediate brewer. I listened to it 3 times yesterday whilst driving in my automobile.

 

[peteru]

No good posting links to iTunes content - it requires way too much effort to listen. If there's a link to an MP3 or AAC file, fine, but not something that requires you sign up to Apple and install their software (which isn't available for my operating system anyway)

 

[pos]

Get a fridge.. An stc or similar and never have to **** about or worry again.

Word.

 

[yankinoz]

If you don't want to shell out for a fridge, thermostat and heat belt, you can make do with a junked fridge even if it doesn't work. A makeshift arrangement like that can give you good temperature control if you're vigilant or experienced. Been there. I have a thermostat and never use it

Alex Tas gave a good list of possible bad effects of poor control. Fusel alcohols and excessive esters result from going too high, sulphur from low temps. In addition, drops in temperature can cause premature flocculation and a stuck fermentation.

During the first few days of the active phase, the challenge is to dissipate the heat produced by fermentation. That is also when most fermentation off-flavours are produced. Blue ice does that quite well. With experience you'd learn how much (and what sizes) to put in at your bedtime, but until then you need to get up once in the night and check temps.

On US brew forums you'll find that a lot of people use "swamp coolers," the towel and blanket arrangement described by Alex Tas. But most US brewers outside the warmest states ferment beer in basements that have fairly constant temperatures suitable for ales; the swamp cooler is pretty effective in preventing overheating . If you have a house like that, fine, but obviously on the first floor of most Australian houses temperatures vary by quite a few degrees.

Once fermentation slows, a fermenter inside a non-running fridge will stay close to the house's average temperature day and night. Or you can wrap insulation around the fermenter. Just be sure you don't insulate until fermentation slows way down.

Some yeasts are more tolerant of wide swings than other. I believe Coopers includes Mauribrew ale yeast with their kits for that reason. Some people say US-05 is good over a wide range, but I haven't tested it that way.

 

[yoboseyo]

My mistake was insulating on the first night, which is probably why it shot up to 3C higher than ambient temp. I brought it down 2C the following day and it's been sitting at 20C for the last day or so. I can put the bucket in a bigger bucket with some water, but I don't need to do this anymore as this batch is past the most active stage. I think it will be a good idea next batch to get past the most active stage

 

[Matplat]

Seriously, you can get second hand fridges CHEAP! I got mine from a user on here for free... they're on gumtree all the time for $50 or less. Possibly the best value bit of brewing kit you will ever acquire.

 

[GalBrew]

Seriously, you can get second hand fridges CHEAP! I got mine from a user on here for free... they're on gumtree all the time for $50 or less. Possibly the best value bit of brewing kit you will ever acquire.

Agreed, I got my original fermenting freezer for $50 off eBay 5 years ago. Still going strong. It doesn't have to break the bank, and is a lot less dicking around than swamp coolers, ice bricks and the like.

 

[Mardoo]

The most I've ever paid for a second-hand fridge was $50, and a couple were free from Freecycle/Trash Nothing. I got a free freezer from there 4 years ago and it's going strong.

 

[MastersBrewery]

Yep fridges are cheap! We had I think 7 at my old place. The current kitchen fridge was a throw out from one of the neighbours, they had it out on the front lawn, I asked if I could take it, replaced a fan that cost me $20 hasn't skipped a beat in 3 years.

 

[yoboseyo]

Problem here is space, not cost. Apartment living

 

[droid]

If you are in an apartment with temperature control ~ ie constant temp of 18-20C or thereabouts then pitch US05 a coupe of degrees under your apartments ambient temperature and let it rise.
Yeasts have a range and you can choose what temp within that range best suits your circumstances but I think the idea is then to leave it at your chosen temp and not let it fluctuate if possible.

 

[GalBrew]

A small bar fridge should be able to fit a
single fermenter. If you are serious about brewing you really need temp control.

 

[stilvia]

No good posting links to iTunes content - it requires way too much effort to listen. If there's a link to an MP3 or AAC file, fine, but not something that requires you sign up to Apple and install their software (which isn't available for my operating system anyway)

https://www.youtube.com/watch?v=rFk5MRAmApQ

 

[peteru]

Thanks for the working link. The way yeast propagation was explained has left me with a question about building up a starter. My interpretation of what John had to say (combined with some extra information gathered here) is as follows...

After the yeast cell has gone through the adaptation phase and has built enough reserves to subdivide, it ought to be able to split about 4 times, at which stage the reserves are more or less depleted and the yeast needs rest to maintain optimum health. If you use the right quantity of starter wort, you should be able to achieve that by running out of fermentables at about the right time. My understanding is that approximately 2L-3L of wort in the 1.020-1.030 range should be the ball-park quantity for stepping up one test tube of Wyeast.

Would that understanding then translate into the following process?

1. Prepare 2L of 1.025 unhopped wort.
2. Cool to 20-22C and add yeast.
3. Place on stirplate for 12-24 hours and maintain temperature.
4. Remove from stirplate and maintain temperature until yeast starts settling at the bottom.
5. Once yeast has settled, decant the liquid on top.
6. When ready to pitch, top up to 2L mark with the wort you are actually going to brew.
7. Put starter on the stirplate and spin as fast as you can for half an hour or so.
8. Pitch entire starter into the fermenter.

The idea being that steps 1-5 take the yeast through a whole propagation life-cycle and return the population to a healthy and dormant state. Steps 6-8 then take the yeast through the first part of the adaptation phase and the stirplate agitation facilitates the introduction of oxygen right at the start where it matters the most.

How does that sound?

And when is Yeast Forge going to be back in stock?

 

[Reman]

I'm not sure why people don't want to use hopped wort for starters, when im making starter wort I always throw in a few pellets for the 10min boil. The anti-bacterial properties of hops means that you are so much less likely to introduce contamination via a starter.