Help detecting infection

[PedroAugusto]

Hi,

This year, I have brewed apple cider from fresh apples for the second time. The first time, it went great. This time, I have come across some issues that have been discussed here before, but, just to be certain, I would really appreciate if you could give me an opinion based on the photos.
The fermentation took a while to become audible. The airlock wasn't bubbling. As I was afraid I had underpitched my last year's dry yeast, I bought a fresh one and opened the lid. There were, however, a few white spots on top, but it smelled like the fermentation was slowly going. Within a few hours of pitching this new yeast, it bubbled intensely for a week.
Eventually, the bubbling stopped, I left it to rest for a bit more than a month, and prepared for bottling. When I opened the lid to bottle, those white spots were still there and in greater number. As you can see in the picture, there are two kinds of formations: the white spots, and these cloudy yellow clutters. I have read around here that these might be yeast. Can you confirm that it's not ruined? Why does this happen? I decided to bottle the cider anyway, siphoning the middle clear part as it smelled and seemed to taste normal cider.
Thanks

 

[myndflyte]

Well for one, the airlock not bubbling could be because fermentation didn't start, or because the lid wasn't fully sealed. By taking it off, and putting it back on, it could have been the yeast you pitched, or the resealing of the lid that finally gave you those bubbles. Really the only way to tell if fermentation isn't happening is a gravity reading.

All that being said, if it tasted fine, then it probably will be fine. You didn't mention if you carbonated or not but one thing that might tip you off to an infection is if the cider becomes a little carbonated (if you didn't carb it) or you get gushers (if you did carb).

 

[PedroAugusto]

Actually, that's true. When bottling the cider, it was very carbonated - that is, it was carbonated before doing the second fermentation in the bottle....

 

[RPh_Guy]

Fresh-pressed unpasteurized apple juice is full of wild yeast and bacteria.

The film on top is simply a visual indicator that they are active in there.
They're not dangerous and nothing to worry about since the flavor is fine.
However, there are strategies you can use to avoid wild growth and minimize chance of off-flavor.

Since fermentation produces CO2, it's totally normal and expected for it to be fizzy after fermentation.

one thing that might tip you off to an infection is if the cider becomes a little carbonated (if you didn't carb it) or you get gushers (if you did carb).

Cider isn't like beer. Beer MAY become overcarbonated from a wild yeast contamination because SOME wild yeast can ferment dextrins that brewer's yeast leave behind.
In cider, all the sugar is simple, so the yeast he pitched will ferment it dry, leaving nothing left to ferment by wild yeast. There will never be gushing bottles from a dry cider (with appropriate amount of priming sugar).
Also, even in beer, certainly not everything that forms a pellicle will super attenuate, and not everything that super attenuates forms a pellicle.

Cheers