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Like the title says, after I chilled my wort I realized the kit I ordered did not come with yeast, an error on the packers fault. Because of my work schedule I wasn't able to pitch the yeast for about 6 days. When I did finally go to pitch the yeast there was what looked like mold growing on top in the shape of bubbles over the wort. I scraped it all off with a spoon, but I'm not sure if the beer is still good. I went ahead and added the yeast anyways, but I'm wondering if I should even bother continuing the process?

EDIT: Checked the wort today, looks like its beginning to ferment. This is three days after adding yeast, 9 days after the boil. maybe good, who knows It did not appear to be Lactobacillus but I obviously can't say for sure. It seemed a bit more blue in color.

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If you can visibly see mold on it, but still want to try fermenting it, just throw it back on the stove, heat it to a boil, and chill it again. It won't do anything for the flavor that was imparted on the wort, but it'll at least kill off any bad bacteria that has settled in. –  Scott Jan 11 at 2:04
I'm interested to see how this comes out. Do please share updates. –  CDspace Jan 11 at 3:55
"there was what looked like mold growing on top in the shape of bubbles over the wort". Mold doesn't look like bubbles; it looks more like scum on the surface of the wort. Yeast creates krausen -- a creamy layer of foam. Since there's no activity after pitching yeast, I wonder if the beer has actually fermented spontaneously from wild yeast. Have you checked the gravity? –  Tobias Patton Jan 13 at 19:17
It was definitely mold spores on top of bubbles. They had a a white a blue color (almost like blue cheese) –  user6269 Jan 14 at 0:37
Did it look similar to this? That's a pellicle formed from Lactobacillus, and not mold. –  Scott Jan 14 at 17:55

3 Answers 3

Sorry, but your beer is probably not going to be drinkable. If you're lucky, the wort was infected by a wild yeast. In this case, it may taste a little funky but will still be beer. The more likely scenario is that your beer was infected by bacteria or mold, and will be unpleasant or undrinkable.

Since you've already pitched the yeast, you might as well wait until fermentation is complete and judge the results then. Give the finished beer a sniff, and unless the smell indicates that it's obviously ruined, have a taste. Maybe you'll get lucky.

In the future, if you have to wait days between cooling and pitching, try to keep the wort as cold as possible. Since it's winter, keeping it outside is a good option. The cold temperature will suppress the metabolism of yeasts, molds and bacteria.

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Great suggestion with putting it outside in the winter. If you can freeze it, all the better. Chest freezer would work just as well, just bring it inside the morning of when you expect the yeast to arrive to allow it to warm up to pitching temperature. –  Scott Jan 11 at 2:03
I was going to ask if it's okay to freeze the wort, but I guess it is. –  CDspace Jan 11 at 3:56
In the case of preserving the wort before pitching yeast, you have two options: freeze it, or boil it. Freezing is often more energy efficient, therefor it is the cheaper option to go with, plus you won't have to continually dilute with water due to evaporation. –  Scott Jan 11 at 4:49

If it's a style suited to souring, maybe it'll end up interesting… :S

But you left un-sterilized sugar-water alone for 6 days. Bacteria reproduce really fast, much faster than yeast actually, but the side-effects of a healthy pitch of yeast usually crowd them out.

I don't have high hopes.

If you're limited on fermenter space, dump it and get the next batch going. If you're not, let it ride and see if you get lucky.

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I would add the yeast and see what happens. Hopefully the fermenter was sanitized before you added the wort. In any case the wort would have been in contact with the air since it's been in there. Once you add the yeast and it starts fermenting (and creating c02), that will push the air (and whatever's in it) out of the fermenter.

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