Classic 'what is this on top of my cider' post

[extremecarp]

I've been making batches of cider from my own homegrown apples. I have not used any sulfites in the fermentation process, but I am using additional yeast (specifically for this batch, Mangrove Jacks M02 Cider Yeast). (I might start using sulfites prior to primary after this!)

I am racking off post primary fermentation a couple of times to secondary vessels for gravity-based clarification (i.e., waiting a week or two) and then I move to capped bottles for secondary fermentation. I've had a couple of pellicles before on batches sitting in these secondary vessels and they looked like the fairly classic biofilm with the odd bubble that you see in pictures. Unfortunately most of them (the secondary vessels) have a fair bit of headspace, although I'm trying to reduce with modifications to my process.

This batch, however, has the developed the following on top. It might be a pellicle but I'm not experienced enough to know the range of appearances. Obviously, I am concerned about mould. Note that the SG of this batch when put into the vessel for clarification was around 1.000 so there's no ongoing fermentation to speak of to provide any bubbles. It doesn't smell strange (normal cidery smell). I've not tasted it yet.

Thoughts?

 

[Yooper]

The picture is really close up, and I can see the clumps. I can't tell if they are clumps of yeast or not though. But it does look like a film from the bottom pictures- is that what's happening? Are you also getting a film over the top?

It's NOT mold (which is fuzzy usually) but it does look like some sort of contamination. The lack of sulfites or other sanitizing of the must is the likely cause, but all of that headspace makes it worse.

 

[extremecarp]

Sorry, here is some better context. The photos were taken looking down onto the surface of the cider. This is the side of the container - you can see they are all floating on the surface and adhering to the sides, which is what made me think it's probably just a biofilm albeit of a type I've not witnessed before.

 

[Andreas Könberg]

I have that too! I have no idea what it is but it really sticks if you put a ladle into it right? I have had to scrub my one ones clean thoroughly afterwards.

It is safe to consume though, what I gather anyway, I have however problems with my cider being far too acidic, you might have the same issue?