Stuck fermentation?

[mauri_sarasvuo]

I am using mangrove jack's M21 for my witbier. OG was 1.050 and now 2 weeks later SG was 1.020. It has been in room temperature for the whole time except in the last week my room temperature has fallen a bit due to fall.

Should I just wait a few more days with this or is it safe to bottle already? Or do I have to restart the yeast somehow?

 

[BrewnWKopperKat]

Pro tip: sharing a complete recipe helps with troubleshooting.

While we wait for the recipe, SG 1.020 is worth exploring.

What is the estimated FG for the recipe?

What are you using to measure FG? If you are using a refractometer, are you adjusting the measured value appropriately (e.g. alcohol has an impact on the measurement)?

 

[mauri_sarasvuo]

Pro tip: sharing a complete recipe helps with troubleshooting.

While we wait for the recipe, SG 1.020 is worth exploring.

What is the estimated FG for the recipe?

What are you using to measure FG? If you are using a refractometer, are you adjusting the measured value appropriately (e.g. alcohol has an impact on the measurement)?

Recipe:
- 1.3kg Flaked wheat
- 1.3kg Pilsen malt
- 0.35kg Flaked oats
- 25g strisselstpalt
- Mangrove jack's M21

I am using hydrometer for measuring and according to brewersfriend recipe creator the FG should be around 1.013

 

[BrewnWKopperKat]

brewersfriend recipe creator

@mauri_sarasvuo : can you share

1. the link to the BrewersFriend recipe?
2. notes that you have about water adjustments?
3. notes that you have about measurements you took during the mash?

 

[BrewnWKopperKat]

also ...

It has been in room temperature for the whole time except in the last week my room temperature has fallen a bit due to fall.

... time & temperature measurements would be helpful to determine if the yeast may have gone dormant.

 

[mauri_sarasvuo]

@mauri_sarasvuo : can you share

1. the link to the BrewersFriend recipe?
2. notes that you have about water adjustments?
3. notes that you have about measurements you took during the mash?

https://www.brewersfriend.com/homebrew/recipe/view/1304944/witbier-v2
I don't have any notes about water adjustments or fermentation temperatures.

 

[MikeCo]

What was your mash temperature? If you mashed significantly higher than the recipe assumed, the FG will be high.

 

[hottpeper13]

I'm assuming you know to mash a Wit at a low temp to get around a 1.010 FG. That said M21 is a finicky yeast and mine always take 21 days to finish with a rising step fermentation. I pitch at 64* and set to 68*. when the krausen falls a little(3-5 days) I bump it to 72*. On day 14 it's 1.020 , on day 21- 1.010. It's worth the time since for the flavor it gives.

 

[Calder]

Mash temp?

What was the batch size. Seems a pretty efficient conversion to get 1.050 for a 5 US gallon batch. Since you are using metric units (I think most on here are in the US ..... but not all), you probably are doing a different size batch.

 

[bracconiere]

kinda an unorthodox question on my part, but that's a lot of unmalted grain....how long are you letting the hydro settle in the cylinder?

 

[Zambezi Special]

Let it sit and measure FG again in a couple of days to see if it is stable or still moving

 

[mauri_sarasvuo]

What was your mash temperature? If you mashed significantly higher than the recipe assumed, the FG will be high.

I'm assuming you know to mash a Wit at a low temp to get around a 1.010 FG. That said M21 is a finicky yeast and mine always take 21 days to finish with a rising step fermentation. I pitch at 64* and set to 68*. when the krausen falls a little(3-5 days) I bump it to 72*. On day 14 it's 1.020 , on day 21- 1.010. It's worth the time since for the flavor it gives.

Mash temp?

What was the batch size. Seems a pretty efficient conversion to get 1.050 for a 5 US gallon batch. Since you are using metric units (I think most on here are in the US ..... but not all), you probably are doing a different size batch.

I believe that the mash temperature was fairly high. Possibly around 155F. Could it have such a noticable effect on the FG?

This was a small batch of about 3 gallons.

 

[hottpeper13]

When using a high % of flaked grains the mash needs to be low. If done at 155* for 60 min you might be done. Raise the temp to 72-74* and give it a gentle swirl,check at 21 days.

 

[Calder]

I have never mashed at 155 F. I'm usually around 150, or less, so I really don't know how temp affects attenuation. 60% attenuation seems low, and it could be due to high mash temp. How accurate is your thermometer, and where did you take the temperature (6.5 lbs of grain is a sizeable mash, and unless everything was well mixed, the temp measurement could be off). I;m asking of you really think the temp was representative of the whole mash?

155 is high and could explain the low attenuation.

If it is really sweet, you could add some plain sugar to reduce the FG (sugar will fully ferment and lower the FG ....... but will increase the alcohol. Another option (if the brew needs any work - it may be fine as is), is to boil some sugar with additional water (increase volume, reduce FG, and also increase overall alcohol). This would dilute the flavor, so take any step like this knowing what the result will be.

 

[bracconiere]

kinda an unorthodox question on my part, but that's a lot of unmalted grain....how long are you letting the hydro settle in the cylinder?

the reason i asked, gelatinized un converted starch in the liquid will make the reading happen slower....might want to let the hydro sit for 15-20 minutes....

edit: something else to try would be to do an iodine test on it...put a bit on a plate them give it a couple drops of 'titratable' iodine...if it's blue then there's unconverted starch in it, if clear you're good....

 

[zbynek]

Hi, something similar is currently happening to me with M21, OG=1.065, after two days it was 1.032, after six days it's 1.024... Slowest fermentation with MJ yeast so far for me. Constant temp 70°F whole time, yeast rehydrated with piece of wort before pitching. Will wait few days more and keep on measuring.