What caused this?

It looks like you have an acetobacter or brett infection.

Yes, you can use it to make vinegar.

The prurle coating is most likey wine pigments that have bonded to the glass. I am not real sure of the chemistry involved there, but it should wash off.

Try a strong Clorox solution if the stain doesn't wash off with hot water. Lum Del Mar, California, USA

I would be a little hesitant to use this wine to make vinegar until you determine what is the problem with it.

What does the wine smell like? Acetobacter has a distinctive smell. If it smells like vinegar then you have a good chance. If it smells bad and tastes bad could it be infected with something else then it will not make a good vinegar.

Joe

I'm not concerned with cleaning the jug, in fact I just pitched it in the recycle bin this morning since I have way too many 1 gallon jugs already. (Btw, if someone is in need of 1 gallon glass jugs, Vitamin Cottage has organic apple juice on sale for $3.99/gallon)

Rather, I was wondering if this symptom might be indicative of what type of infection was present. I thought perhaps those of you who make vinegar might have seen this coating. I've never seen this happen with any of my wine before.

I'll try to compare the smell again next to some red wine vinegar. Any other way to identify the different infections besides a microscope?

I make a lot of vinegar and really don't get any coatings like you describe, but it's usually made from older wines too. My Syrah's drop a coating like this if not fined with Sparkalloid though.

I usually get rid of all that cellulose that builds up over the years; I make two or three batches and fight it out of the carboy. It can form a pretty thick 'clump'. There can be a film but it washes right off.

That sounded like mycoderma to me, I can't say whether it would make good vinegar or not. I'm pretty sure mycoderma converts alcohol to water among other things so it may not be the best idea to use it.

Joe

Hi Lum, Nice to hear from you on this forum. Best regards, Joe