# Bohemian Lager Yeast (Mangrove Jack's M84)



## AzfromOz

Hi,

Am brewing a Kolsch from a recipe. The recipe called for specific Wyeast or Whitelabs kolsch yeast strains that aren't available near me, so I decided to go for a German ale type yeast, also without luck. Settled on a Bohemian lager yeast, given that Kolsch beers are similar to lagers. That yeast wants to ferment at the 10 - 15 degree temperature range. The recipe wants the wort to ferment at 21 degrees, which to me seems high for the yeast type even if I had the recommended yeast. Anyway, fermentation started within 6 hours at 21 degrees and is still happily bubbling away near 48 hours.

Question: given the yeast type, should I drop the temp to, say, 15 degrees after say, day four, and then lager it for a couple of weeks, or just let it ride it out at 21 degrees and bottle and condition once fermentation has stopped. Pros and cons of either?

cheers


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## goid

I haven't used bohemain lager yeast, but I would bring it down to the recommend range for the yeast now. Leave it within that range for 3 weeks than lager for a couple.


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## earle

Go with the temp recommended for the yeast. The recipe yeast instructions aren't really valid for you anymore as you have changed the yeast.

On Kolsch yeasts though - I usually start off at about 14 for a week, then increase to above 20 for another week for a yeast clean up before cold crashing. Sounds like your recipe might have just gone with a recommended temp for a single temp ferment.


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## Drewski

Would drop the temp ASAP, Instructions you read are for a top fermenting Ale yeast not a lager.. Also with a dry lager yeast usually two packets are suggested to get the initial yeast count. You did start high temp wise which some people do to get yeast kicking with lagers, but would drop to recommended temp which would be between 12-15deg.


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## AzfromOz

Thanks, everyone, for the tips. Have dropped to 15 degrees now as per yeast instructions. Will sit for one week at that temp and then see what the beer is doing. 

Cheers!


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## Bribie G

It's a really good yeast that attenuates and cleans up well, I used it with their Pilsner kit and a pack of brew enhancer with dark dried extract to make a sort of Vienna Lager, and it was hard to pick as a kit n kilo.


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## fraser_john

Bribie G said:


> It's a really good yeast that attenuates and cleans up well
> <snip>


I use it in a large variety of lagers and it is an excellent, clean yeast. So good in fact I bought the soon to be expired 500gm pack($35 from memory!) from Craftbrewer and repackaged into 25gm vac sealed bags. Though soon to expire, I have not seen any difference in its quality.


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## Bribie G

Off topic but I reckon that if a company such as Mangrove Jacks, any company, had introduced a full range of specialists dried yeasts ten years ago, then Wyeast and Whitelabs would have been really up against it.

Liquid yeasts are great, but I think most of their attraction until now is that the dried yeast market was almost in a fossilized state until recently. Notto. US-05. S04.Three lager yeasts and a German ale or whatever, end of story.

To my surprise I've been having great results with their Northern Brown, Burton Union and Bo Lager.

Go Mangrove


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## AzfromOz

Now to selfishly put the focus back on me, I realise I just did something stupid. I turned the temperature control down to 15 in one hit, rather than stepping it down, meaning the temperature crashed to 15 and all of the yeast, presumably, died. Within an hour, when I first checked, all fermentation had ceased. So.... should I try to salvage the beer by putting another packet of dried yeast into the fermenter? It was fermenting happily until I dropped the temperature, so I assume there's still sugars in there for the yeast to convert. Or should I just let it sit for two tot three weeks at 15 degrees and see what happens?

Any advice appreciated!

cheers


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## Rocker1986

What is the size of your batch? It probably wouldn't have dropped the liquid (wort) temp that far in only an hour. It takes a few hours normally, if it's a 'normal' ~23 litre batch.


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## verysupple

The yeast won't be dead, it would have just floccuated and dropped to the bottom. If you keep the temp. constant and keep rousing the yeast then eventually (I dunno, maybe half a day, a day...) they should start fermenting again. You just put 'em to sleep, that's all.


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## AzfromOz

It's a 21l batch. Maybe one hour after was a stretch but definitely within two hours. 

How does one go about rousting yeast? Temperature will remain constant due to the keg king regulator and my grandma's fridge.


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## Bribie G

Lager yeasts at their normal operating temperature don't produce much krausen and appear to be inactive. Give it a few more days and you should see activity, such as a growing layer of yeast on the bottom of the fermentor.


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## indica86

verysupple said:


> The yeast won't be dead, it would have just floccuated and dropped to the bottom.


Lager yeasts are bottom fermenting so that is where they should be.


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## indica86

Bribie G said:


> To my surprise I've been having great results with their Northern Brown, Burton Union and Bo Lager.
> 
> Go Mangrove


The British Ale is brilliant, I am a big fan.


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## AzfromOz

Bribie G said:


> Lager yeasts at their normal operating temperature don't produce much krausen and appear to be inactive. Give it a few more days and you should see activity, such as a growing layer of yeast on the bottom of the fermentor.


Even with no activity in the airlock? Been a while since I checked as I'm offsite, but the airlock went from happy activity to nothing last time I checked.

Will check the yeast cake when I get back for reference purposes. 

Cheers


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## Barge

I don't want to be a party pooper but...

I brewed a BoPils late last year with the m84 and buggered up the settings on the fridge. Pitched it warm (19/20) then tried to bring it down quickly. Long story short, I now have a batch that is almost undrinkable. Ethyl acetate like nobody's business. I'm hoping it will clear up but it's been 2 months now and it isn't getting much better.

Hopefully your experience is better. My advice is to make sure you taste it before racking off the yeast cake as I may not have left it long enough to absorb the off flavour.


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## Rocker1986

Airlock activity doesn't really mean much... it probably stopped due to the change in pressure inside the FV from the temperature drop. However, look for signs of activity in the brew itself such as a small krausen, or condensation on the inside of the lid etc. or even take a quick SG sample to see if it's dropped.


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## AzfromOz

Barge said:


> I don't want to be a party pooper but...
> 
> I brewed a BoPils late last year with the m84 and buggered up the settings on the fridge. Pitched it warm (19/20) then tried to bring it down quickly. Long story short, I now have a batch that is almost undrinkable. Ethyl acetate like nobody's business. I'm hoping it will clear up but it's been 2 months now and it isn't getting much better.
> 
> Hopefully your experience is better. My advice is to make sure you taste it before racking off the yeast cake as I may not have left it long enough to absorb the off flavour.


Thanks. How long did you let it sit on the yeast cake before racking? Mine's only at day three now so I intend to leave it for at least another couple of weeks. Long time to wait just to see if you've stuffed your beer!




Rocker1986 said:


> Airlock activity doesn't really mean much... it probably stopped due to the change in pressure inside the FV from the temperature drop. However, look for signs of activity in the brew itself such as a small krausen, or condensation on the inside of the lid etc. or even take a quick SG sample to see if it's dropped.


No krausen yet, but possibly the smallest amount of movement in the airlock - both sides now no longer dead even....

Will take a gravity sample in a couple of days.

Cheers!


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## Barge

I can't remember how long exactly but it was only in primary for around 7-10 days. I did a diacetyl rest and figured that lagering in secondary would be enough to clean it up.


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## goid

Lagering is more to drop proteins and other stuff from the beer to produce clearer beer. For clearing up undesirable by products it is better to keep at fermentation temp so the yeast can convert them to better by products. Once the yeast run out of sugars for food they can get there energy from the undesirable by products.


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## AzfromOz

Goid said:


> Lagering is more to drop proteins and other stuff from the beer to produce clearer beer. For clearing up undesirable by products it is better to keep at fermentation temp so the yeast can convert them to better by products. Once the yeast run out of sugars for food they can get there energy from the undesirable by products.


Ok, thanks.

No krausen, no airlock, no condensation. Will rouse the yeast tomorrow and see what happen, keeping the fermenter at 15 degrees.

cheers!


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## Bribie G

Let cling wrap be your friend.
Airlocks are a hangover from the day when home brewers were the poor cousins of wine makers and used similar equipment. 

Cling wrap has the main advantage that you can get a good view of what is going on. 
In most cases with a bottom fermenting yeast, even if there is no krausen you can look across the top of the brew and see fizzy pinpoints of gas escaping.


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## verysupple

indica86 said:


> Lager yeasts are bottom fermenting so that is where they should be.


My lagers always have a small krausen for a few days even at 9 degrees, but that's beside the point. Even if there is no krausen, there should be yeast in suspension, not just sitting at the bottom.


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## AzfromOz

Happy to report that gravity readings, condensation and, finally, some airlock activity, means I am well down the route of making beer. Taste test from the gravity reading came up with no off flavours that my untrained palate could detect. In fact I drank the entire sample, which is a first, and now that I think about it, one of the benefits of fermenting a cold temperatures!

Will lager for three weeks before bottle conditioning.

cheers, and thanks for all the advice.


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## Randai

So after having done three lagers with this, two marzen's and a pilsner. It has a real sort of grapey tart flavour that I was picking up in it. Not a lot of sulfur in the finished product that I could detect.
Honestly it was quite nice, but yeah definite flavour that I can't describe better than a sort of mild grape + tartish sort of flavour.


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## rude

Just wondering if there any good reviews on this yeast
Saw pic of Fletchers Pils in whats in a glass & has me wanting to use it
What are crew doing for 4.5% to 5% beers 23 litres ?
2pkts rehydrated at 13 degrees ?
Any pressure ferments with this yeast ?
Cheers Rude


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## goatchop41

rude said:


> Just wondering if there any good reviews on this yeast
> Saw pic of Fletchers Pils in whats in a glass & has me wanting to use it
> What are crew doing for 4.5% to 5% beers 23 litres ?
> 2pkts rehydrated at 13 degrees ?
> Any pressure ferments with this yeast ?
> Cheers Rude



Rehydrate a bit warmer - fermentis recommend 20-25oC for lager yeast. That's obviously just for the rehydration, not fermentation. And yes, I know that it's an MJ yeast, not Fermentis. But dry yeast is dry yeast


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## fletcher

rude said:


> Just wondering if there any good reviews on this yeast
> Saw pic of Fletchers Pils in whats in a glass & has me wanting to use it
> What are crew doing for 4.5% to 5% beers 23 litres ?
> 2pkts rehydrated at 13 degrees ?
> Any pressure ferments with this yeast ?
> Cheers Rude



overpitch in my opinion. super clean, and fast, ferment. 60-90 seconds of o2 if you can.

incidentally, that pils was made using slurry from my previous lager made with m84. it was a no-chilled beer i had sitting at about 4-5c. i rehydrated 3 packs and pitched at about 8c and let it free rise to ~11c where it stayed for about 2 weeks.

the pils was then pitched with a HEAP of that slurry (about 5 or so times the required pitching rate) and finished within about 5-6 days. never made a cleaner lager.

i don't mind the yeast. it's not my favourite of lager yeasts, but i prefer it over w34/70. i haven't tried s-189 but i'll be doing a similar beer using it and seeing how it fares.


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## BJB

My guess is M84 and S-189 are the same yeast.


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## TheSumOfAllBeers

Fletcher what don't you like about 34:70 ?


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## peteru

I used M84 in a dark Czech lager and it worked really well. It allowed the malt to come through really well. I used a 2L active starter and O2.


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## rude

goatchop41 said:


> Rehydrate a bit warmer - fermentis recommend 20-25oC for lager yeast. That's obviously just for the rehydration, not fermentation. And yes, I know that it's an MJ yeast, not Fermentis. But dry yeast is dry yeast



No worries goat
I new rehydrate at higher temp but was asking about ferment temp my bad
Looked around a bit will go for 3 pkts for say a 4.5% first then pitch a 5% wort on top of the slurry
No o2 though  so will try to ferment at the top end of the scale recomendations for the first one
Sounds like the s189 fermentis is the same yeast so might go with either one depending on LHBS availability


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## Batz

Hard to beat IMO.
I love this yeast for lagers and pilsners, prefer it 34/70 myself.

https://www.craftbrewer.com.au/shop/details.asp?PID=842


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## goatchop41

rude said:


> No o2 though



Get yourself a metal paint stirrer from the big green shed and stick it in to end of a drill. Doesn't get as much O2 in to solution as pure O2 injection/diffusion stone, but it's much, much better than just shaking the fermenter/pouring back and forth a few times.


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## rude

no worries 
I no chill so pour in from height
Will get an o2 kit next year though as it has to be the way


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## goatchop41

rude said:


> no worries
> I no chill so pour in from height
> Will get an o2 kit next year though as it has to be the way



As I said, the paint stirrer gets much more O2 in than just pouring from a height (which is actually a piss poor excuse for oxygenation), and is much cheaper than an O2 kit - it'll get in enough O2 for all but the biggest beers


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