View Full Version : Mold or yeast? The age old question

12-31-2011, 08:53 PM
Title says it all pretty much. Just got another batch of Ancient Orange that's about a week away from being done. Is that white stuff mold or just yeast deposit? Thanks guys.

12-31-2011, 10:20 PM
Hmm...I'm leaning towards yeast, but have a few questions.

Were the grapes/raisins golden when they went in? If not, I'm a little concerned with how white they look, but having only made true JAO once myself, I can't say if the dark raisins loose their color as well.

Second question is did you rinse the fruit in any way before adding? The orange in particular. It could be mold from the skin of the orange.

And finally, what does it smell/taste like? If it is noticeably bad or "off", it could well be mold.

All that said, it's probably yeast. Other microbes have a hard time living in such a harsh environments (high sugar, high ABV, low pH, some SO2 from the yeast...you get the idea. :p)

Chevette Girl
01-01-2012, 04:16 PM
Hee hee, those raisins do look kind of anaemic, don't they... but what I'd expect if they're golden.

Looks to me like yeast deposited on the orange peel... I'd suggest you give the carboy a gentle swirl, most of it will fall off, I've generally found that mold usually sticks to things and has to be scraped or scrubbed off and will stay together in a blob even once it's removed, yeast mostly doesn't stick to itself or anything else and will fall off once gravity isn't holding it on anymore (although sometimes it sticks to the carboy neck in funky patterns above the waterline).

01-02-2012, 09:26 AM
I mean, they're both fungi, so in general, especially considering the kinds of molds that enjoy growing on oranges, they will enjoy similar environments.

A decent way that i learned in microbiology to tell, probably even a magnifying glass would work, is that most fungi grow in what are called hyphae, little tree-like formations, which is what gives mold its fuzzy appearance, while yeast has a more linear, bacteria-like formation, and doesn't generally grow outward from the surface it spreads across. So you might be able to tell from appearance.

I hope this is at all informative.

01-02-2012, 03:13 PM
Thanks for this tips. Yes, they were golden raisins, and they always turn out white like that, so I don't think that's an issue. And I scrubbed the crap out of the orange too haha. I haven't tasted yet, I didn't want to void Joe Matiolli's warranty :P I guess I'll find out in a few weeks then when I bottle.