I recently traded for Heady Topper in hopes of brewing a clone. Long story short I found fruit flies in the starter. I purchased all the hops and grains for the beer which I planned to do next week. What do?
fruit flies are a great carrier of things that should never be introduced to beer. sadly, I would say sayonara starter.
I voted for use, but did it mistakenly. No I would not use that starter. A fruit fly in the mash, however, is something I would not worry about.
I don't have a recipe in front of me, but IPAs are typically pretty expensive beers because of all the hops. You can get yourself some wyeast/white labs/dry yeast and still have a nice ipa, or you can risk something awful. Think of it as opportunity: (1) to make a different IPA and (2) to trade for another Heady Topper.
I've had fruit flies get into fermenting beer, leaving a white, bubbly film on top. I've never dumped the beer, and luckily always finished drinking all of the batches before they go south. I'm not sure how those fuckers find a way into the carboy/bucket, but they do, and I hate them for it.
Timing is everything here. If they get into a fermenting beer, the yeast population probably was big enough to swamp out the effects of the bugs by outcompeting them for sugars and by making a hostile beery environment through pH and alcohol effects. On the other hand, if they made it into a starter that was made from bottle dregs, there could easily have been a time when the yeast to wild bugs ratio was not so skewed, and the bugs end up playing a much greater role in the beer's destiny. There are some cool microbial ecology studies this could inspire for the true experimentalist, but if one is just after some decent homebrew, I say better safe than sorry.
Interesting username to be commenting on a fruit fly problem A lot of interesting and unknown things can be riding along with fruit flies, some of which can take a good amount of time to produce any sort of off-smell/flavor into a starter, especially with no hop presence in said starter. I would a) toss the starter if you're only looking to do a clean IIPA or b) brew a small, 1-2gallon, wheat sort of beer to pitch the peachy-forward Conan yeast into with the hopes in it becoming a wild ale...maybe even toss some peaches in it down the road. In option b's case, you will eventually find out if that starter was OK from the get-go and then you'll have a good sized cake to move forward. If it turns out smelling horrible, toss it...we are all guilty of an experiment gone bad once in awhile.
I don't have good data, but based on forum anecdotes, the risk of infection from a fruit fly incursion seems to be the risk that most often turns into actual infections vs. other risks. Well, that and Starsan dipped garden rocks.
I would select an available yeast and get a new starter going. Try for the dregs again another time, or get more Heady Topper. If you want to clone it, I am sure you could live with having to drink a few more cans of it. Call it continuing research...
The starter was covered with foil and had a small hole poked in it. Probably not the best idea to leave it that exposed, esp right next to a fruited berliner going. Looks like I am going to take the communities advice and use the yeast for a very small batch for experimental purposes but not waste the $70 Northern Brewer bill on that experiment. Also VikeMan ISO garden rocks
The beer MIGHT turn out okay, but why risk it? Fruit Flies are carriers of acetobacter. Acetobacter won't turn sugar to vinegar. It won't compete with yeast for the available sugars. The issue is that acetobacter take the already fermented beer and converts the alcohol into acetic acid, making vinegar. Alcohol and pH don't impact acetobacter as this is where it flourishes. Ever notice how all RR sours taste like vinegar, even at 8+% ABV? It requires oxygen to do this though. If you are able to make the beer in an O2 free environment post yeast, flush everything with CO2, rack via force with CO2, keg and purge more, DH in a keg fully purged, and don't open that keg, drink it fast, you MIGHT be able to keep from it becoming vinegar. But why risk it? IPA is an expensive beer to make, lots of premium hops are hard to come by. You could end up with some really bitter and aromatic malt vinegar. It might be good on fish? I hit the same problem once, had a fruit fly get in my starter of 3F Gueze, expensive beer, couldn't go get another one to build up. Had to dump it. Granted, this was going in a beer that was to age in bulk for over a year, and I would be getting into it every month or so to taste it (introducing O2), and then bottle condition for years. Better safe than sorry.
