Yeast and kit temperature

[mikeyjay84]

Thanks for everyones input. Jai - sorry i kinda hijacked your thread, although its developed a bit. Lots of info.
My next brew will be a 9 litre, so given i dont have any crazy mishaps likes sliced fingers and busted can openers, i will be watching the temps VERY closely.

 

[graysalchemy]

Impressive amount of discussion in such a short time! Good stuff.

So basically whilst it's not ideal it should turn out ok. I did it last night and this morning it was 22deg, so not too high.

I would still aim to keep it a bit lower as Hawks says 1-2 degrees can make a hell of a difference to these little buggers. :thumb:

 

[anthonyUK]

For anyone wanting more detail I recommend the yeast book by Chris White and the man whose name I always forget ( starts with a Z though ) :thumb: It's a bit heavy going in places, but there is a lot of very good and detailed information in there including showing the different compounds created by fermenting at temperatures with just 5c difference.

It is a good book Hawks. I'm slogging through it still.
The other guy is Jamil Zhainasheff from the Brewing Network podcasts who has recently gone pro.

You are right that 5°c makes a difference when fermenting but not so much during the growth phase. I agree not to risk it though especially if you are relatively new to it :)

 

[graysalchemy]

You are right that 5°c makes a difference when fermenting but not so much during the growth phase.

The growth phase is the most critical period temp wise

 

[Hawks]

It is a good book Hawks. I'm slogging through it still.
The other guy is Jamil Zhainasheff from the Brewing Network podcasts who has recently gone pro.

You are right that 5°c makes a difference when fermenting but not so much during the growth phase. I agree not to risk it though especially if you are relatively new to it :)

That's the chap, I really should remember...

I would agree that 5c for growing up a starter for example where you don't care about the taste of the resulting 'beer' is fine - in fact to get the healthiest yeast doing this at around 25c is optimum.
However, when you are pitching to ferment and you do care about the taste of the finished product the temps are key and you want to be aiming for that 20c. The flavours are in that initial 48 - 72 hours

 

[graysalchemy]

Growing on yeast at 25c and then pitching is likely to make have made the yeast choose a different metabolic path and thus the resulting growth in the wort will also be the same ie fusal.

 

[anthonyUK]

Growing on yeast at 25c and then pitching is likely to make have made the yeast choose a different metabolic path and thus the resulting growth in the wort will also be the same ie fusal.

I don't think it works like that. Current doctrine indicates 25°c is good for stepping up.

One example -

http://www.maltosefalcons.com/tech/yeas ... -practices

Temperature.  Another important factor which influences yeast growth and metabolism is temperature.  Temperature is somewhat neglected in terms of its role in influencing growth rate and fermentation performance.  Most brewing yeasts will actually grow and ferment at temperatures up to 98 °F (37 °C).  These high temperatures are not optimal for yeast propagation or fermentation, since they produce numerous esters and affect the overall viability and stability of the yeast.  86 °F (30 °C) is the usual temperature for the growth and propagation of laboratory yeast but this is still too high for brewing yeast.  Room temperature or 77°F (25 °F) is the recommended temperature for propagating brewing yeasts.   At this temperature rapid growth and fermentation occurs without any adverse affects on subsequent fermentation performance.  Although ale yeast will grow just fine up to near 90 °F, lager yeasts start to lose viability at high temperatures.  The mid 70s are optimal for growing lager yeasts and higher temperatures should be avoided.

 

[graysalchemy]

Fair enough :thumb: :thumb:

I was always lead to believe it had similar consequences as using simple sugars, the resulting yeast.

 

[anthonyUK]

Anyone can see why there are so many discussions regarding yeast

It is great that we are able to maintain this level of discussion without reducing ourselves to the level of the aussies :thumb:

 

[Hawks]

Fair enough :thumb: :thumb:

I was always lead to believe it had similar consequences as using simple sugars, the resulting yeast.

I was surprised as well when I read it... as it stands I don't usually have somewhere to increase to 25c, so it gets left around 20c still - but nice to know it's not an issue for propagating.

 

[graysalchemy]

That is why brewing is such a complex thing and why consistency is difficult without some element of temp control throughout the brewing. :thumb:

 

[Hawks]

That is why brewing is such a complex thing and why consistency is difficult without some element of temp control throughout the brewing. :thumb:

Yep - looks like I need a 4th fridge / heating cupboard

 

[mikeyjay84]

Wow, i have learnt so much this morning. I've been more productive here than at work! :whistle: oops :thumb:

So a quick noob question: propagation is essentially breeding right? i.e. initial stages before yeast start to eat sugar and the fermentation starts?

 

[anthonyUK]

So a quick noob question: propagation is essentially breeding right? i.e. initial stages before yeast start to eat sugar and the fermentation starts?

Yeah. Within limits, the more you can oxygenate the starter, the more yeast you'll grow which is why a stir plate is used.
Yeast during the aerobic stage tend to multiply without creating too many unwanted compounds.
A starter grown on a stir plate will yield multiple times the amount of non-stirred.
For more details have a read of the article I linked to. It is a decent overview and for a much more in depth look, try the Yeast book mentioned earlier.

 

[anthonyUK]

The growth phase is the most critical period temp wise

Just for clarity if anyone should read this in the future.

I wanted to check the Yeast book beforehand but the above statement is incorrect despite the emoticons :lol:

Page 67 of the Yeast book covers this quite comprehensively.

To reiterate though, unless you are confident using yeast it is best to stick to the recommended temperatures.

 

[jonnymorris]

I don't have my copy to hand. Would you care to enlighten us on the main points of p.67?

 

[anthonyUK]

It does say that at higher temperatures the yeast will not create off flavours but will create precursors so you should raise the temp at the end of the ferment to clean up.
Other than these precursors yeast produce minimal flavour compounds or ethanol so esters are also not a concern.
Rapidity of growth will however affect flavours later on. To what degree and with what it doesn't say at this point but does go on to say it is acceptable to do so with a small but acceptably sized pitch but should not be a panacea for an inappropriate sized pitch.

 

[jonnymorris]

If rapidity of growth affects favours and is linked directly to temperature (higher temp, faster growth) how is GA's comment incorrect?

Not trying to be funny, just trying to understand. Does the book suggest which is the most temperature critical phase?

 

[graysalchemy]

That is assuming that you pitch correctly though. I still stand by the fact that the precursors of Fusels and esters are produced in the early stages and the higher the temp the more likely that you will get fusels.

 

[anthonyUK]

That is assuming that you pitch correctly though. I still stand by the fact that the precursors of Fusels and esters are produced in the early stages and the higher the temp the more likely that you will get fusels.

No probs and I think we all just want as much clarity as possible for anybody else reading this.

There is an online Chris White article which is pretty much what his book contains.
Well worth a read - http://www.brewgeeks.com/the-life-cycle-of-yeast.html