Fermentation Translation

Discuss all aspects of fermentation
Post Reply
benchharp
Sober
Posts: 5
Joined: Thu Aug 22, 2019 4:29 pm

Fermentation Translation

Post by benchharp » Wed Nov 27, 2019 11:20 pm

Hi, I've done several simple brews now and am looking to pay more attention to fermentation temperature control.

I thought it would be as simple as fermenting at x degrees but the recipe i have has lots of fermentation steps and i'm looking for a little help in translating them if possible.

Here are the instructions:

Fermentation Profile

Collect 15ºC
Trim 17ºC
1045º 22ºC
Diac Rest 22ºC
Condition 18/12ºC
Dry hop 18ºC
Stabilise -2ºC

If anyone could talk me through the steps and roughly how long these steps are for. I know it would only be a rough guide.

Appreciate any help.

Thanks

McMullan
Drunk as a Skunk
Posts: 882
Joined: Tue Jul 14, 2015 7:48 pm
Location: Here

Re: Fermentation Translation

Post by McMullan » Thu Nov 28, 2019 7:30 am

Chill wort to 15; pitch yeast @ 17; after a day or two let it free rise to 22 or heat slowly; leave at 22 for a few days after primary fermentation; cool to 15 for conditioning. That's my interpretation. I'd dry hop before conditioning. Minus 2 should probably be +2, but fridge temp should be fine - just takes a bit longer.

Edit: Thought I'd add a note on 'conditioning' as it seems to cause some confusion. Generally, it simply means reaching your desired CO2 volume, in a bottle or a keg. If you use kegs you can dry hop when you like. If you don't you can't. I'm assuming you're not using kegs yet. Also I'm assuming you're fermenting an ale. Here you don't really need to do a 'diacetyl rest'. Which recipe are you following exactly?
Last edited by McMullan on Thu Nov 28, 2019 11:32 am, edited 1 time in total.

User avatar
Kev888
So far gone I'm on the way back again!
Posts: 7629
Joined: Fri Mar 19, 2010 6:22 pm
Location: Derbyshire, UK

Re: Fermentation Translation

Post by Kev888 » Thu Nov 28, 2019 11:27 am

That seems quite a rigorous programme! Yes, I broadly agree with McMullan. Though I must admit that I don't always do all these things, in particular I rarely collect chilled wort much cooler than the pitching temperature, though in some systems doing so can make it easier to then adjust to the exact pitching temperature wished for.

The reason generally given for then pitching below the main fermentation temperature (at 17ºC in this case) is to restrain the yeast's initial enthusiasm. Growing too fast is said to produce less desirable by-products in some cases and also use up more of the available nutrients. I have a suspicion that it might also be a carry-over from days before good temperature regulation, which may have struggled to prevent temperature rising too quickly. If one has pitched cool like this, the main fermentation temperature should then be reached over a day or two.

The 22ºC is then the main fermentation temperature. Generally it is moderated to levels that give best flavour (rather than what the yeast like best) so is different for different yeast and brewer's wishes. Warmer tends to give more character from the yeast, so it depends on what degree is wanted.

The diacetyl rest is done towards the end of fermentation (and/or at the end). In this case it just entails leaving things as they are for a couple of days, and probably isn't even necessary as it has been there already. But had the fermentation been cooler (especially at lager yeast temperatures) then temperature would need raising to the 22ºC first. The warmth helps the yeast clean up diacetyl (often described as a butterscotch flavour), which isn't desirable in large quantities in many styles of beer.

Conditioning can simply mean priming the beer to generate some carbonation, and 18ºC is pretty typical for that. However, there are other post-fermentation processes, during which the yeast convert undesirable by-products of both the primary fermentation and the priming fermentation (and I believe there are also chemical changes). So whilst some people may instantly chill once fermentation completes, if time allows it can be better (and sometimes ultimately faster) to let the beer just cool a bit to sit (or bulk mature) at cellar temperatures (about 12ºC) for a couple of weeks to a month - though much more is also fine.

The chilling to or just above -2ºC is generally done to help clarify the beer; essentially as cold as possible without freezing (the alcohol helps there). Chill haze forms and then settles out quicker, as does other fine matter. The removal of such things is potentially more than cosmetic, in that the beer can be less affected (more stable) in storage without some of them present. However, given more time most will also settle out at cellar temperatures so chilling isn't an actual requirement.

The order of these latter stages may depend on your process; for example if bottling it may best to bulk mature at twelve degrees and then chill to clear before bottling and conditioning at eighteen degrees.

...There are of course differences in opinion on the best way and even the reasons for things, so not sure if this is precisely what the author of that fermentation profile was thinking. And I omitted even talking about dry hopping because these days people do it at all sorts of stages from very early in fermentation right through to afterwards or later, and dry-hopping can also be done in the cask. So maybe treat that as a subject in itself.
Kev

benchharp
Sober
Posts: 5
Joined: Thu Aug 22, 2019 4:29 pm

Re: Fermentation Translation

Post by benchharp » Sun Dec 01, 2019 10:35 pm

[quote=McMullan post_id=846768 time=1574922621 user_id=15744]
Chill wort to 15; pitch yeast @ 17; after a day or two let it free rise to 22 or heat slowly; leave at 22 for a few days after primary fermentation; cool to 15 for conditioning. That's my interpretation. I'd dry hop before conditioning. Minus 2 should probably be +2, but fridge temp should be fine - just takes a bit longer.

Edit: Thought I'd add a note on 'conditioning' as it seems to cause some confusion. Generally, it simply means reaching your desired CO2 volume, in a bottle or a keg. If you use kegs you can dry hop when you like. If you don't you can't. I'm assuming you're not using kegs yet. Also I'm assuming you're fermenting an ale. Here you don't really need to do a 'diacetyl rest'. Which recipe are you following exactly?
[/quote]

Hey thanks, that makes a lot more sense. Its a cloudwater dipa. https://docs.google.com/spreadsheets/d/ ... w/htmlview

So, if i chill to 15, do i then heat back up to 17 before pitching? Yeah, not using kegs, just bottling and carbonating with sugar.

benchharp
Sober
Posts: 5
Joined: Thu Aug 22, 2019 4:29 pm

Re: Fermentation Translation

Post by benchharp » Sun Dec 01, 2019 10:38 pm

[quote=Kev888 post_id=846771 time=1574936857 user_id=5506]
That seems quite a rigorous programme! Yes, I broadly agree with McMullan. Though I must admit that I don't always do all these things, in particular I rarely collect chilled wort much cooler than the pitching temperature, though in some systems doing so can make it easier to then adjust to the exact pitching temperature wished for.

The reason generally given for then pitching below the main fermentation temperature (at 17ºC in this case) is to restrain the yeast's initial enthusiasm. Growing too fast is said to produce less desirable by-products in some cases and also use up more of the available nutrients. I have a suspicion that it might also be a carry-over from days before good temperature regulation, which may have struggled to prevent temperature rising too quickly. If one has pitched cool like this, the main fermentation temperature should then be reached over a day or two.

The 22ºC is then the main fermentation temperature. Generally it is moderated to levels that give best flavour (rather than what the yeast like best) so is different for different yeast and brewer's wishes. Warmer tends to give more character from the yeast, so it depends on what degree is wanted.

The diacetyl rest is done towards the end of fermentation (and/or at the end). In this case it just entails leaving things as they are for a couple of days, and probably isn't even necessary as it has been there already. But had the fermentation been cooler (especially at lager yeast temperatures) then temperature would need raising to the 22ºC first. The warmth helps the yeast clean up diacetyl (often described as a butterscotch flavour), which isn't desirable in large quantities in many styles of beer.

Conditioning can simply mean priming the beer to generate some carbonation, and 18ºC is pretty typical for that. However, there are other post-fermentation processes, during which the yeast convert undesirable by-products of both the primary fermentation and the priming fermentation (and I believe there are also chemical changes). So whilst some people may instantly chill once fermentation completes, if time allows it can be better (and sometimes ultimately faster) to let the beer just cool a bit to sit (or bulk mature) at cellar temperatures (about 12ºC) for a couple of weeks to a month - though much more is also fine.

The chilling to or just above -2ºC is generally done to help clarify the beer; essentially as cold as possible without freezing (the alcohol helps there). Chill haze forms and then settles out quicker, as does other fine matter. The removal of such things is potentially more than cosmetic, in that the beer can be less affected (more stable) in storage without some of them present. However, given more time most will also settle out at cellar temperatures so chilling isn't an actual requirement.

The order of these latter stages may depend on your process; for example if bottling it may best to bulk mature at twelve degrees and then chill to clear before bottling and conditioning at eighteen degrees.

...There are of course differences in opinion on the best way and even the reasons for things, so not sure if this is precisely what the author of that fermentation profile was thinking. And I omitted even talking about dry hopping because these days people do it at all sorts of stages from very early in fermentation right through to afterwards or later, and dry-hopping can also be done in the cask. So maybe treat that as a subject in itself.
[/quote]

This is great, i think i have a much clearer picture. It's my first brew that i'm going to control the fermentation temperatures so all this is new to me.

Really appreciate your feedback.

User avatar
Kev888
So far gone I'm on the way back again!
Posts: 7629
Joined: Fri Mar 19, 2010 6:22 pm
Location: Derbyshire, UK

Re: Fermentation Translation

Post by Kev888 » Sun Dec 01, 2019 11:42 pm

If it is all new, then the key thing to concentrate on is the main fermentation temperature (plus if you prime then that stage also needs to be warm enough for the yeast to work). Many of the other steps are relative subtleties that people may choose to bother with or not, according to the situation and their preferences.
Kev

Robwalkeragain
Hollow Legs
Posts: 372
Joined: Tue Jun 05, 2018 9:19 am

Re: Fermentation Translation

Post by Robwalkeragain » Mon Dec 02, 2019 6:00 pm

That looks over complicated for standard ale tbh.

Collect a few degrees below target - free rise to fermentation temp and hold it there - diacetyl rest varies by yeast but it’s usually around 15c? - gradually cool once free from diacetyl and sulfur to as close to freezing as possible.

Dry hop varies but i find 3-4 days warm, 3-4 days cool works well.

benchharp
Sober
Posts: 5
Joined: Thu Aug 22, 2019 4:29 pm

Re: Fermentation Translation

Post by benchharp » Wed Dec 04, 2019 7:19 pm

[quote=Kev888 post_id=846818 time=1575240137 user_id=5506]
If it is all new, then the key thing to concentrate on is the main fermentation temperature (plus if you prime then that stage also needs to be warm enough for the yeast to work). Many of the other steps are relative subtleties that people may choose to bother with or not, according to the situation and their preferences.
[/quote]

So to keep it simple it sounds like i can initially cool the wort to 17ºC
Pitch the yeast and wait for the gravity hits 1045º (should i take Gravity readings daily?)
Then raise the temperature to 22ºC
Then Dry Hop at 18ºC
Before Cold Crashing at as close to 0ºC as my fridge will go.

I can then bottle and add sugar to carbonate - this will need to be in a warmer environment so that the yeast reacts with the sugar, if i've understood correctly?

Thanks for all your help.

User avatar
Kev888
So far gone I'm on the way back again!
Posts: 7629
Joined: Fri Mar 19, 2010 6:22 pm
Location: Derbyshire, UK

Re: Fermentation Translation

Post by Kev888 » Wed Dec 04, 2019 9:29 pm

That general kind of thing seems reasonable to me. However, I must admit that monitoring the gravity for the initial temperature rise is a step beyond what I bother to do, and I suspect that is so for most homebrewers and many micros.

Once the yeast start to multiply/grow you will usually see signs of CO2 being produced, visible on the wort's surface, and this is also when many of the flavour and aroma compounds (and alcohol) start to be produced. The yeast will generate heat, which causes the wort to naturally rise in temperature until it reaches the main fermentation temperature, whereupon it should be regulated. Though small batches in cool environments may sometimes need a bit of added warmth to help them along.

If you want more such yeast-derived character then you may allow (or help) the wort to rise in temperature sooner and to a higher main fermentation temperature, or in fact start it off there (as a great many brewers routinely do). If you want less then let (or make) it rise more slowly, perhaps over three or four days, to a modest main/final fermentation temperature.

The 'sooner' or 'slowly' might best be judged by the wort's gravity, but for me if the yeast are progressing normally ( e.g.no unusual lag times) then I'm happy to guestimate and just use time (I would not do so for judging other things, such as final gravity being reached).
Kev

McMullan
Drunk as a Skunk
Posts: 882
Joined: Tue Jul 14, 2015 7:48 pm
Location: Here

Re: Fermentation Translation

Post by McMullan » Wed Dec 04, 2019 10:23 pm

benchharp wrote:
Sun Dec 01, 2019 10:35 pm
So, if i chill to 15, do i then heat back up to 17 before pitching?
It's what I do generally. By the time the wort is transferred to an FV and aerated - at room temperature - it's close to 17℃.

Post Reply