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Mangrove Jack's M20 Yeast

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noshadow

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Yesterday I started an extract Hefeweizen recipe from the Cooper's website. It suggested to use Munich yeast so I've used a Mangrove Jack's M20 yeast. The fermentation range for the yeast is 18-30°C but I'm just wondering what temperature to leave the FV at. My wife is quite keen on the banana taste you get from wheat beers so to try to achieve that I'd originally planned to keep the temperature at about 24°C thinking that would be at the high end of the yeast. It wasn't until I opened the pack I saw it could be used as high as 30°C

Should I stick to 24°C or will I need to up it to try to get the banana flavours?

It also crept up to 26°C overnight and I got a bit of krausen through the airlock but it's back at 24 now and no more blow off since overnight. It's a 33 litre bucket with only 21 litres in it so I was surprised the krausen was enough to come through the airlock, especially in less than 24 hours. Should that be a concern if I up the temperature? I've rigged a blow off tube now to catch any more.
 

chthon

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Once the kraüsen has dropped, it won't appear again.

Since the temperature raised and then dropped, I suppose it will be better if you increase the temperature again for a couple of days to make it ferment out.

I hope you get the banana taste, because I haven't obtained it yet with this yeast, although I was able to obtain the cloves in a kristalweizen.

Ferment for a week, bottle, condition and carbonate for two weeks. I hope you have strong bottles, because you should normally bottle this with 3,5 to 4 volumes of CO2.

Good luck.
 

noshadow

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Thanks for the quick reply!

Was it a mistake to let it drop back to 24°C? I'll get the heat belt back on and get the temp up. I was planning on leaving it for 2 weeks to ferment (using the 2/2/2 rule that seems to be commonly advised here)

For carbonating Coopers advise up to 9g per litre but looking at brewers friend I'd need about 11-12g per litre for 3.5 to 4 volumes. Are Coopers under-priming at their rate? I'll just be using PET bottles for it.

Hopefully I can get some banana taste or my wife won't be best pleased 😬
 

chthon

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Was it a mistake to let it drop back to 24°C? I'll get the heat belt back on and get the temp up. I was planning on leaving it for 2 weeks to ferment (using the 2/2/2 rule that seems to be commonly advised here)
For most yeasts, MJ also recommends this, but for the M20 they recommend either one week of fermentation and two weeks carbonation, or two weeks fermentation and one week carbonation.

I think 24° C is good, it was more of "don't let it drop further", and let the yeast do its work at a stable temperature.
 

chthon

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For carbonating Coopers advise up to 9g per litre but looking at brewers friend I'd need about 11-12g per litre for 3.5 to 4 volumes. Are Coopers under-priming at their rate? I'll just be using PET bottles for it.
This discussion seems to indicate that higher is better, and that 9g/l might be a bit too low. FWIW, I have German weizen bottles, and I have carbonated at 4 volumes without problems.
 

Maxonian

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I brewed a Hefe with the M20 a few weeks ago. I pitched at 22C and it raised itself to 26C 24 hours later before dropping back to 22C. Mine ended up mega banana-ey with very little clove so I think you’re on to a winner on that front.

It finished at 1.020 down from 1.051 but it wasn’t overly sweet. It was very drinkable and I’ve only got 1 bottle left. Based on the flavour profile that you’re aiming for I think you’ll be pleased with your results.
 

Rossih2006

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Let us know how you go on with this. Ive currently got a hefe on brew that i started at around 18c for a couple of days and then ramped the temp up a degree a day until it hit 23c. Have dropped it back to 21c and will force carbonate in a corny keg prob on tuesday with the aim of being able to drink by the weekend.
 

PerthRod

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If it's banana flavour you're looking for - I can highly recommend this :


I've just done a couple of batches of wheat beer using this yeast and it does exactly what it says on the packet !
 

chthon

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In the meantime I have also used the last of my M20 to brew a weizen. I pitched at 22° C, and I put the fermenter in a place which is normally cool, but where the sun shines in on the longest days of the year. Most of the fermentation was done in two days, I noticed that on Saturday evening the temperature in the room was almost 30° C, but that was at the end of the second day.

Definitely smells like banana now, though. Bottled yesterday, and since it still warm, I will already try a bottle at the end of next week.
 

noshadow

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I've kept mine at about 24-26° C for 16 days. Took an SG at day 13 and it was only down to 1.014, took another today and it's down to 1.012. Blow off tube is still bubbling away every couple of minutes. I was hoping to bottle it this week but I'll leave it until late next week.

I am picking up some banana but not too strong, maybe that'll come out more after being bottled a few weeks?
 

chthon

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As reference, I got down from 1.046 to 1.012, probably in two days, but certainly in 7 days, which gives me an attenuation of 74%, which falls nicely into my statistics of brewing with this yeast.
 

chthon

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Further references from my brew with M20 this year. I bottled one week after fermentation (at reasonably high temperatures, between 22° C and 29° C), I let it carbonate and condition for one week before I put one in the fridge for 24 hours. Tasted yesterday, really nice beer, tastes like a weizen, only a bit of clove and banana, not even bubblegum. A very clean beer in fact.

Process parameters:
  • Added 100 g of glucose in the hope of getting banana
  • Fermented rather warm
  • Did not underpitch, because I wanted to clear the rest of sachet. According to my calculations, the pitch rate was 1, in this case 5g of yeast for 7l of beer.
  • Open fermentation for two days
 

Maxonian

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I think open fermentation might be the way forward for this yeast. I’ve used it twice and both times the beer finished at 1.020. I think it might be sensitive to CO2 pressure buildup in the headspace, similar to the way certain saison yeasts are.
 

noshadow

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I've realised I neglected to update this thread as to how it progressed after conditioning. It finished fermenting at 1.010 so an ABV of 4.5% and now it's been almost two months since it's been bottled. The banana has definitely come to the fore since being bottled so my wife is very happy with the results, as am I!

I would definitely use this yeast again but next time I think I'll try the WHC Banana Split yeast PerthRod recommended just to see if I can get even more banana.
 

UKSkydiver

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... and I got a bit of krausen through the airlock but it's back at 24 now and no more blow off since overnight. It's a 33 litre bucket with only 21 litres in it so I was surprised the krausen was enough to come through the airlock, especially in less than 24 hours.
Similar experience - I have ~10 litres in a 15 litre FV and I have a bit of krausen on the lid where it had clearly got a bit frisky at the start.
 
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