delicious infection?!?

[stevetree]

So the first time this happened was after bottling. The cider was crystal clear, but after a week or two in bottles it turned cloudy and developed a sour flavor. It was actually pretty good and we wondered how to replicate it. Fast forward a few weeks...Now its in our fermenters. Fermentation has slowed, the cider takes on a lighter, yellower color and does not clear. No strings, no goop, it's just yellowish, cloudy, and sour. Again, the flavor is pretty good, and it hasn't made us sick. After doing some research, my best guess is a Lacto infection. I know many people take advantage of a MLF to convert malic acid into a milder lactic acid, but I don't think that's what is going on. Lactobaccilus will supposedly convert sugar into lactic acid. I've also noticed white/cream colored stuff on the sides of the fermenter. It looks a lot like yeast, but I've never had yeast stick to the sides like that. It's happening in primary, so I doubt it is turning to vinegar. Plus the flavor is more like a strong lemonade, rather than like vinegar. Any thoughts?

P.S. After all these batches are finished I will be using bleach on all equipment, just in case, and going back to the iodine based sanitizer before starting new batches. We're usually pretty good about sanitizing, but something slipped by us. Oh, i think it may have had something to do with eating summer sausage while brewing, maybe some of its lactic acid cultures?Oops!

 

[gregbathurst]

The best test for whether it has turned a bit vinegary (acetic) is to take a sniff - vinegar has quite a distinctive smell. In spain the native yeasts used in cider produce a bit of acetic acid, they quite like their cider a bit acetic.
It isn't really possible for lactobacillis to make your cider more sour because there is already plenty of acid in cider. Malic acid tastes quite sour but lactic acid is much less sour. lactobacillis doesn't produce malic acid, only lactic so you are proposing that the lacto first consumes the malic than the sugar, but it doesn't happen that way, the yeast consumes the sugar.
The most likely thing is that there was a small amount of residual sugar, when yeast consumed this last bit of sugar it tasted sour because the sugar masks the sourness. perhaps your infection was brett.