Fermentation temp difference expectations

[Grott]

Temp control of fermentation is well documented but I was wondering about what differences in the end result could you expect from a basic Coopers kit where one batch is fermented at 18 degrees and another at 24 degrees? Both fermentation’s left for 14 days at those temps.
In other words with your basic kits like Coopers is it a big deal?

 

[manticle]

Yes

 

[TwoCrows]

Kit and kilo and allgrain still require temp. control. This will care for and assist the yeast and the rate that they consume and reproduce

 

[Grott]

Perhaps I haven’t expressed this well. The two fermentation’s are temp controlled, one at 18 and the other at 24 degrees. What difference would you expect at completion? Taste, smell, before/after carbonation?

 

[manticle]

Asking what the difference actually is and asking 'is it a big deal' are pretty different.

At the higher temps ( presuming that's actual wort temp during ferment, not ambient) - more pronounced esters, more fusel/solvent/hot alcohol and accelerated yeast breakdown.

 

[MHB]

If you used the yeast that came with the there wouldn't be a world of difference. What comes with the kit is -
Going to be a massive under pitch - some yeast stress is inevitable
Chosen to be as insensitive to temperature as possible - selected to work most anywhere in a big country with variable climate
18-24oC would represent a fairly small range for the yeast. Mostly its going to be Mauri 514 Yeast - Mauribrew Ale Yeast.pdf

Yeast is a living thing and it will respond in fairly predictable ways to a given set of conditions, with temp control you will at least get consistent results with less metabolic side issues cooler. For some yeast strains this may not be what you are looking for (think Heffe)
Cooler gives you cleaner with less fusels, esters... and flavour
Warmer gives more flavour, it might just be that not all the flavours are ones you want in your beer.

If your ferment isn't over in 5 days (hit FG) you have underpitched.
Mark

 

[Grott]

Thanks Mark, helpful. I normally control fermentation at 18 to 20 degrees but would be easier in our Adelaide hot temps/heatwaves to control at 22 to 24. (No I can’t have a fermenting fridge).
Just remembered good old John Palmer, looked up fermentation and up to 24 degrees would be “ok”. Mmmm

They say the “proof is in the pudding” so I going to ferment a Coopers English Bitter using dry malt and kit yeast at controlled 22-24 degrees (taking into account the warming up caused fermentation).

Anybody ferment at the higher temps?

 

[manticle]

Proof of the pudding is in the eating (of the pudding).

Most new kit users have likely fermented at that temp and can tell you about it. Will vary between 'it was fine' to ' tasted like cider and piss'.

Underpitching, as mentioned above, carries its own set of woes, including increased acetaldehyde levels.

 

[Grott]

Point taken.
The saying is about you can’t judge anything without trying it, thus I have a “liquid pudding” so to speak thus, “the proof is it in the drinking”.

 

[mtb]

There's a lot to be said about temperature fluctuation during fermentation as well. A constant temp of 24 would arguably be less stressful on the yeast than swinging between 18 and 24.

 

[Yuz]

Curious about this as well - is it true that temps for the initial three / four days are most important, whereas the rest of ferment - not as much?

 

[Lyrebird_Cycles]

Yes.

The most important aspect is growth rate, which generally increases with temperature*. Total amount of growth also has an impact: you need more growth to finish out the ferment if your pitch rate is lower.

Most of the yeast growth occurs in the first part of ferment, so it is more important.

In general, secondary metabolites accumulate more quickly at higher growth rates.

The classic example is ester formation: the fast the yeast grows, the greater the level of acetyl coA it needs to support growth. The greater the level of acetyl coA, the greater the level of acetate esters such as amyl acetate.


* Until it doesn't, most brewing yeasts top out around 30 oC.

 

[Shadime]

While we are on the subject of yeast. I have started to brew 12L batches. I use US-05 and rehydrate and O2.
Is the whole packet too much yeast or is 1/2 packet too little.

I only brew ales of around OG 1040-1045
Cheers

 

[mtb]

While we are on the subject of yeast. I have started to brew 12L batches. I use US-05 and rehydrate and O2.
Is the whole packet too much yeast or is 1/2 packet too little.

I only brew ales of around OG 1040-1045
Cheers

1pkt for 12L is just fine. I often pitch 2pkts for a 21L batch.

 

[Lyrebird_Cycles]

If you are happy where you are, stay there, but a half pack is certainly worth a try.

I routinely use a single 11g pack of Nottingham to pitch 28 litres or so of wort at about 13 oP and haven't experienced any problems.

 

[Shadime]

Thanks for the replies, and sorry for hijacking the thread.
I have been using 1/2 packet, might see how a whole packet goes.

 

[Grott]

No hijacking of thread, all interesting and related.
Now interested in temps for say the first 5 days of a 14 day ferment.