Wyeast 1968 London ESB and diacetyl rest

Discuss all aspects of fermentation
User avatar
Fr_Marc
Steady Drinker
Posts: 49
Joined: Sat Apr 10, 2021 10:09 am

Wyeast 1968 London ESB and diacetyl rest

Post by Fr_Marc » Thu Apr 15, 2021 4:30 pm

Dear fellow brewers,

my first ever all grain brew is currently in the fermenter happily bubbling away. I pitched the yeast (Wyeast 1968, London ESB) on April, 8th. The fermentation temperature has constantly been 18.5°C (65°F). I am expecting to hit final gravity this weekend.

The package of Wyeast 1968 states that “a thorough diacetyl rest is recommended after fermentation is complete”.

Being the newby I am, I wonder how I should proceed now. I was thinking about leaving the ale in the fermentation vessel for another week after hitting FG and rising the temperature to 21°C (70°F) during this time. The idea is “letting the yeast clean up after itself” before bottling. I would then bottle, using dextrose drops and let the bottled ale sit for another two weeks at 21°C for carbonation.

Would this procedure count as “a thorough diacetyl rest”? And would there be enough active yeast in the ale for carbonation? Or would you suggest bottling first and holding the diacetyl rest afterwards? Or another procedure altogether?

Thank you for your suggestions!

Marc

User avatar
Eric
Even further under the Table
Posts: 2873
Joined: Fri Mar 13, 2009 1:18 am
Location: Sunderland.

Re: Wyeast 1968 London ESB and diacetyl rest

Post by Eric » Thu Apr 15, 2021 5:20 pm

Diacetyl is a fault most noticeable in pale lagers from Pilsner malts.
British ales that are casked and served with a small amount of live yeast present and are both conditioned at cellar temperature will clean up while carbonating.
Diacetyl rests are not a must do procedure with British ales fermented with British ale yeasts. Some beers can be served with diacetyl at a level some drinkers might notice.
Without patience, life becomes difficult and the sooner it's finished, the better.

McMullan

Re: Wyeast 1968 London ESB and diacetyl rest

Post by McMullan » Thu Apr 15, 2021 5:31 pm

I think that kind of advice is aimed at Americans generally, whose expectations are being (mis)managed. It's perfectly normal to have yeast contribute flavour in English beers. The whole concept of a specific 'diacetyl rest' is a matter of opinion. Beer seems to mature to arrive at the same inevitable point regardless any any claimed rests.

User avatar
Fr_Marc
Steady Drinker
Posts: 49
Joined: Sat Apr 10, 2021 10:09 am

Re: Wyeast 1968 London ESB and diacetyl rest

Post by Fr_Marc » Thu Apr 15, 2021 5:38 pm

Great, thank you. Would you suggest to raise the temperature at the last days of fermentation nontheless, in order to bring out the flavour of the yeast?

McMullan

Re: Wyeast 1968 London ESB and diacetyl rest

Post by McMullan » Thu Apr 15, 2021 5:47 pm

Yes and no. Or kind of. The key is usually to pitch at 17-18℃ (wort temperature) then let the yeast do the rest. Temperature control mainly helps with keeping temperature above lower limits during cold spells. Inevitably, fermentation produces heat and you should not really need to intervene to increase it.

Edit: in warm spells, you might need to intervene to lower it, obviously.

User avatar
Eric
Even further under the Table
Posts: 2873
Joined: Fri Mar 13, 2009 1:18 am
Location: Sunderland.

Re: Wyeast 1968 London ESB and diacetyl rest

Post by Eric » Thu Apr 15, 2021 6:57 pm

McMullan wrote:
Thu Apr 15, 2021 5:47 pm
Yes and no. Or kind of. The key is usually to pitch at 17-18℃ (wort temperature) then let the yeast do the rest. Temperature control mainly helps with keeping temperature above lower limits during cold spells. Inevitably, fermentation produces heat and you should not really need to intervene to increase it.

Edit: in warm spells, you might need to intervene to lower it, obviously.
My brewery is in a garage that faces a cold North Sea. I will aim to pitch at 19C, but often it is colder. There is heating and insulation but mostly heat generated by the yeast means little external heat is needed once it gets started and will be allowed to rise to 23C maximum before any action will be taken. After 3 or 4 days fermentation will be mostly finished and the beer will be allowed to cool to cellar temperature and clear.
Without patience, life becomes difficult and the sooner it's finished, the better.

McMullan

Re: Wyeast 1968 London ESB and diacetyl rest

Post by McMullan » Thu Apr 15, 2021 7:08 pm

Exactly, Eric. Stringent temp 'control' during fermentation, at least the first day of two, merely risks temperature swings. We need to work with the yeast mainly, by letting them do their thing and allow them to 'free rise'.

User avatar
Fr_Marc
Steady Drinker
Posts: 49
Joined: Sat Apr 10, 2021 10:09 am

Re: Wyeast 1968 London ESB and diacetyl rest

Post by Fr_Marc » Fri Apr 16, 2021 11:01 am

That’s a lot of encouragement. Thank you all!

User avatar
Cobnut
Drunk as a Skunk
Posts: 758
Joined: Fri Aug 24, 2018 4:23 pm
Location: Ipswich
Contact:

Re: Wyeast 1968 London ESB and diacetyl rest

Post by Cobnut » Fri Apr 16, 2021 7:43 pm

I’ve read plenty about fermentation being exothermic, but I genuinely wonder whether at typical home brew batch sizes of c. 20-25L this really has much effect?

If I remember correctly (maybe from another forum), Eric brews batches around 40-50L typically where I think I’d expect the effect of the exothermic fermentation to have a greater impact on wort temperature.

Happy to be corrected if my premise is somewhat “off”.

FWIW, I set my inkbird with a tolerance of +/- 0.5C and generally leave it there unless I’ve planned a “lift” in temperature later in the process. Cooling when the fermentation seems largely complete is also part of my usual process.
Fermenting: nowt
Conditioning: English IPA/Bretted English IPA
Drinking: Sunshine Marmalade, Festbier, Helles Bock, Smokey lagery beer, Irish Export StoutCascade APA (homegrown hops), Orval clone, Impy stout, Duvel clone, Conestoga (American Barley wine)
Planning: Dark Mild, Kozel dark (ish), Simmonds Bitter, Bitter, Citra PA and more!

User avatar
Eric
Even further under the Table
Posts: 2873
Joined: Fri Mar 13, 2009 1:18 am
Location: Sunderland.

Re: Wyeast 1968 London ESB and diacetyl rest

Post by Eric » Fri Apr 16, 2021 9:42 pm

Cobnut wrote:
Fri Apr 16, 2021 7:43 pm
I’ve read plenty about fermentation being exothermic, but I genuinely wonder whether at typical home brew batch sizes of c. 20-25L this really has much effect?

If I remember correctly (maybe from another forum), Eric brews batches around 40-50L typically where I think I’d expect the effect of the exothermic fermentation to have a greater impact on wort temperature.

Happy to be corrected if my premise is somewhat “off”.

FWIW, I set my inkbird with a tolerance of +/- 0.5C and generally leave it there unless I’ve planned a “lift” in temperature later in the process. Cooling when the fermentation seems largely complete is also part of my usual process.
Not so limited, last November brewing Graham's recipe for Westmalle Doubbel was just 14 litres in plastic FV sat on bricks in gardening trug filled with water and an aquarium heater.

I don't have a fermentation fridge, only heat is applied during fermentation except in exceptional circumstances when attenuation is applied using mains water or a maxi if the mains water is too warm.

The fermentation bench holds a 50L, 70L and 100L stainless vessels. Heat is applied by insulated resistance wire wrapped around the vessel under a jacket of insulation. My aim is to replicate what has happened in commercial breweries for a century and more when brewing beers that Britain was famous for. Pitched yeast is plentiful in quantity, good in health and as close in temperature to the wort that is practical to achieve. Some heat is usually applied at the beginning to avoid the wort cooling in early stages as the yeast gets to work, but once it gets to about 21 or 22C, the generated heat is sufficiently significant to require insulation to be removed if there is a cover in place. Those with a fridge set at 18 or 19 may never experience this.
Without patience, life becomes difficult and the sooner it's finished, the better.

User avatar
Eric
Even further under the Table
Posts: 2873
Joined: Fri Mar 13, 2009 1:18 am
Location: Sunderland.

Re: Wyeast 1968 London ESB and diacetyl rest

Post by Eric » Fri Apr 16, 2021 10:19 pm

Further to the above, I wish to clarify my initial posts were in relation to brewing a special bitter or premium pale ale with an ale yeast. In brewing the Westmalle or similar 7% or stronger beer, different temperature control should be used to avoid hot alcohols and for other reasons.

British session beers do not benefit from long and cold fermentations, but this does not apply to all styles and similarly what produces a popular American beer will not necessarily improve a British beer.
Without patience, life becomes difficult and the sooner it's finished, the better.

McMullan

Re: Wyeast 1968 London ESB and diacetyl rest

Post by McMullan » Sat Apr 17, 2021 8:54 am

The problem with temperature controllers in fermentation fridges, if you’re not very careful, is they cause temperature swings as things ping back and forth, potentially extending fermentation. Pitching at 17℃ (for an English ale) works better for me. I do have a fermentation fridge with temperature control, and I do make good use of it, but I get better fermentations if I pitch at 17℃ (yeast and wort), set the temperature controller to 23℃ and unplug the heater so as to allow the temperature to free rise under the control of yeast, heat from their metabolism. Pitching at 17℃ is the temp control. Bearing in mind too that there is a school of thought that says temperature control is more important in the initial/early stage of fermentation when yeast cells are dividing at the highest rate. This is what we need to control mainly. My own observations seem to confirm this.

Worst-case scenario, and we’ve all been here I suspect. I know I have. Cool wort to nominal ‘pitching temperature’ of about 25℃*, aerate, pitch yeast that are slightly above fridge temperature or otherwise much cooler than the FV wort. Set temperature controller to something like 19℃ (the lower limit for the strain used) then slowly ramp up the temperature (towards the upper limit for the strain) very carefully, by a degree per day, pretending not to notice the temperature swings as the fridge and heater compete to compensate for overcompensating :? And sit back and convince yourself fermentation takes 2 weeks.

Wrong. Rather than respond favourably to the sweet aerated wort within several hours, grow and ferment, the yeast are mainly having a biochemical panic attack and hiding at the bottom of your FV.

*Know your wort (all of it, not just the little bit around a temperature probe) is x℃. My preference is the same temperature I’ve set for my fermentation fridge, where the yeast (under barely any spent wort, which was decanted off hours before) have been waiting several hours.

guypettigrew
Even further under the Table
Posts: 2626
Joined: Mon Mar 22, 2010 7:10 pm
Location: Christchurch, Dorset

Re: Wyeast 1968 London ESB and diacetyl rest

Post by guypettigrew » Sat Apr 17, 2021 2:51 pm

Really interesting thoughts. McM.

For today's brew, with WLP 002, I'll cool the wort to 17°C then pitch the yeast. I'll disconnect the heater and set the cooler to a maximum of 23°C, as you do. Usually it would be set a maximum of 19°C, the middle of the supposedly preferred range for WLP 002.

The FV is a SS Brewtech chronical with internal cooling coil and external heat pad.

I'm a bit worried about letting the fermentation get so far above the suggested 19°C, though. Your thoughts would be appreciated.

Guy

Edit: The ambient in the garage where the FV is drops to about11°C, so I've changed it so the heater comes on to maintain a temperature of 17°C and unplugged the cooler.

User avatar
Fr_Marc
Steady Drinker
Posts: 49
Joined: Sat Apr 10, 2021 10:09 am

Re: Wyeast 1968 London ESB and diacetyl rest

Post by Fr_Marc » Sun Apr 18, 2021 9:27 pm

Please allow me to come back to my original topic (kind of...).

The ale has been in the fermenter for 11 days now. Original gravity was 1.050 and is down to 1.013 now. The room temperature where the fermenter is placed has been constantly 18.5 C. The ale in the fermenter has a temperature of 23C by now. The airlock shows no activity by now (no bubbling) and the last sample I took for gravity reading came out pretty clear and bright.
My question is: Is it possible to leave the ale in the fermenter for another 7 days, before bottling (using carbonation drops). I am anxious that there won’t be enough active yeast cells to ensure carbonation by that time. A follow up question would be: If it is possible to wait 7 days before bottling, should I lower the surrounding temperature (i.e. put the fermenter in a 15C cool cellar) or would this be not a good idea?
Thank you again for helping a newbie brewer!

User avatar
Eric
Even further under the Table
Posts: 2873
Joined: Fri Mar 13, 2009 1:18 am
Location: Sunderland.

Re: Wyeast 1968 London ESB and diacetyl rest

Post by Eric » Sun Apr 18, 2021 10:16 pm

Well all I can say is that I've never left an ale in the FV for 11 days, so I can't advise from experience.

I brewed today, 1044 OG, yeast was pitched about 2 hours ago at 20C. It will probably near FG on Wednesday evening or Thursday morning when insulation will be removed and expect it will cool to 12 to 15 C. It will continue to ferment slowly and will be casked when convenient either Sunday or Monday. From about a week later it could be ready to drink.
Without patience, life becomes difficult and the sooner it's finished, the better.

Post Reply