One more: is this contamination?

[Dabrew]

Hi guys,
First of, I am new on this forum, looking forward to expand my knowledge about brewing and getting some light shed on some of my issues
So I brew this white IPA the other day (half of the grain bill was unmalted wheat) and I used two different dry wheat beer yeast strains for it. The OG was 1.070. The fermentation seemed to have stopped with a high final gravity of 1.024 after only a few days but after adding the second dry hopping addition in a hop cylinder (about 12 days after brew day), fermentation started again. It seemed like a new Krausen developed which pushed a lot of small particle of hops from the dry hopping to the surface (in total about 100g of hops were used for dry hopping). I took a reading yesterday after 9 days since the fermentation started again and the gravity has dropped down to 1.004. Also, there is still a very very small activity in the airlock even though the brew day is now about 24 days ago. The yeasts used were medium flocculation strains. To me, the only explanation is a contamination. For the taste, it is obviously bitter and hoppy but I cannot taste any bad flavour or sour taste. The beer is definitely drinkable but does this look like a contamination to you guys? Thanks for your time!

 

[Miraculix]

Which yeasts did you use? How did you take the gravity reading?

 

[Dabrew]

I first pitched the mangrove jack’s Belgian wit yeast M21 after the normal brew day and then I pitched the SafAle s-33 after about 12hrs. Both yeast were first rehydrated using Goferm.
The gravity readings were taken using two hydrometers which gave me the same readings. The beer was about 21c.

 

[davidabcd]

Welcome to the forum!
If your FG reached 1.004, it's not the method of measuring gravity. What was your FG supposed to be? If you overshot it by a lot, that could be a bad indicator.
I don't know what the effects of un-malted wheat would be.
As far as I can see, that's a lot of hops on top and not an infection. I would have said the second foaming and whatnot was due to the dry hopping and not fermentation but gravity dropped a lot afterward. You can confirm what caused what if you kept track of gravity.
Normally, I say never open the fermenter for three weeks but since you have, it would be good to know the full trek of the gravity.

 

[GoodTruble]

Nothing in the photos looks like infection to me (and 97% of the time, it's not an infection). That looks like a beer in the latter stages of fermentation.

1.004 is pretty low, but there can be other, more likely explanations. 24 days is a long fermentation, but also not unheard of (I've had them go 30).

My advice - just ride it out and see. Shut the lid. Wait two weeks. If it then has calmed down and smells/tastes okay, bottle or keg it. There is very little chance anything harmful could be in there that smell or a small taste wouldn't catch. If it is infected, it should just become more obvious in 2 weeks (but I would definitely guess it's not infected).

One of the most enduring pieces of homebrew advice you will see is - give it more time. Only about 1 in 50 batches people are worried about actually wind up having a problem. The rest turn out fine(ish).

 

[Miraculix]

I first pitched the mangrove jack’s Belgian wit yeast M21 after the normal brew day and then I pitched the SafAle s-33 after about 12hrs. Both yeast were first rehydrated using Goferm.
The gravity readings were taken using two hydrometers which gave me the same readings. The beer was about 21c.

M21 might be a diastatic yeast. That would explain the low fg. After all, it does not look like a typical infection, which still could have happened. My bet would be on M21 being a diastatic yeast.

 

[Dabrew]

Thanks for the reply guys.
I thought about M21 or s-33 being diastatic but after some research, I can confirm that both are non diastatic.

One more question: in case of infection, the decrease of density means more alcohol or the sugar is being used by the wild yeast to only produce other compounds than alcohol? Can I still use the FG reading to calculate the ABV?

 

[Miraculix]

Thanks for the reply guys.
I thought about M21 or s-33 being diastatic but after some research, I can confirm that both are non diastatic.

One more question: in case of infection, the decrease of density means more alcohol or the sugar is being used by the wild yeast to only produce other compounds than alcohol? Can I still use the FG reading to calculate the ABV?

Yes you can. The wild yeast also makes alcohol.

 

[GoodTruble]

Sure. You're using a hydrometer? -If so, check it in plain water while you're at it. It should read 1.000 in water, but it's possible the calibration is off and shows under 1.000 (happens fairly often).