Fruit fly on side wall of yeast starter bottle

[luckybeagle]

I have been stepping up a starter of Wyeast 1056 American Ale in a 1 gallon glass jar and found a dead fruit fly on the inside wall of it. It was not submersed in the starter. I wiped it out with a starsan-soaked paper towel as soon as I noticed it. I'm pretty sure it got in at a higher fermentation stage. I proceeded with letting the starter ferment, cold crash and decant, and add more boiled and cooled DME+water. I do not detect any off-smells or flavors. Did I get lucky? I'd really hate to toss this big starter as I've been building it up for a large batch of high gravity Scottish ale that I hope to brew this weekend.

 

[Jayjay1976]

Acetobacter, which fruit flies carry, is a slow-growing bacteria so you might not taste its effects in a starter. But pitch that starter into a batch of fresh wort, and as yeast fermentation is winding down the acetobacter will be winding up to turn all of the ethanol into acetic acid, aka vinegar. If you let it sit around long enough you will eventually end up with a bunch of malt vinegar. I think you should make a fresh starter and this time use a foam stopper instead of tinfoil to keep fruit flies out. Sorry man.

 

[VVbrewery]

I dunno "Do you feel lucky punk?" Otherwise toss it.

 

[NeoBrew]

I stopped using foam stoppers early on and switched to foil. I was never very confident that I was able to clean the foam stopper. Especially after a blow off (Before I built my stir plate) What is the proper procedure for cleaning a foam stopper? Or are they meant to be disposable?

 

[Jayjay1976]

I stopped using foam stoppers early on and switched to foil. I was never very confident that I was able to clean the foam stopper. Especially after a blow off (Before I built my stir plate) What is the proper procedure for cleaning a foam stopper? Or are they meant to be disposable?

If it gets loaded up with kraeusen, a good soak in pbw, squeeze it out thoroughly, rinse in hot water and let air dry before storing. Then soak in star san for a little while before using again. No big deal, the foam is typically not all that dense. I use a stir plate though so my foam stoppers have never gotten very dirty, so YMMV.

The instructor at my lhbs soaks them in iodophore, they have developed a dark yellow/orange color and look to have a LOT of miles on them.

 

[luckybeagle]

Gah... I was afraid that'd be your guys' answer.

I'm all but certain it didn't make it into the starter/wort. It was about 6" from it, clinged to a bit of moisture on the sidewall, which I wiped down when removing it. Really bummed. The yeast cake is huge. If I ferment wort and throw it in a bottle and carb it with some simple sugar, and it tastes fine in a couple weeks do you still think my yeast could be infected?

 

[RPh_Guy]

I think you could use the yeast. There's obviously higher risk of contamination with the insect in there, but when making so many steps you have to expect the additional risk of contamination.
Personally I probably would not take the risk and toss it, but I'm also a big fan of vitality starters to avoid some of the contamination risk among other things

I sincerely doubt all fruit flies have acetobacter and all fruit flies only have acetobacter. That's like saying all mosquitoes carry malaria (Plasmodium falciparum) or all ticks carry lyme (Borrelia burgdorferi)... Not quite.

Also, acetic acid bacteria require 4 things to make vinegar: Warm temperature, Time, Alcohol, and Oxygen. Hopefully any acetobacter in your beer will be deprived of at least one of those things, or you're doing it wrong.

It's the other things the fly may have carried in that are concerning, wild yeast specifically. There's no easy way to know if it's contaminated.

Hope this helps.

 

[Jayjay1976]

I think you could use the yeast. There's obviously higher risk of contamination with the insect in there, but when making so many steps you have to expect the additional risk of contamination.
Personally I probably would not take the risk and toss it, but I'm also a big fan of vitality starters to avoid some of the contamination risk among other things

I sincerely doubt all fruit flies have acetobacter and all fruit flies only have acetobacter. That's like saying all mosquitoes carry malaria (Plasmodium falciparum) or all ticks carry lyme (Borrelia burgdorferi)... no.

Also, acetic acid bacteria require 4 things to make vinegar: Warm temperature, Time, Alcohol, and Oxygen. Hopefully any acetobacter in your beer will be deprived of at least one of those things, or you're doing it wrong.

It's the other things the fly may have carried in that are concerning, wild yeast specifically. There's no easy way to know if it's contaminated.

Hope this helps.

This actually makes a lot of sense to me, thanks for the tune-up!

 

[George MacDonald]

I stopped using foam stoppers early on and switched to foil. I was never very confident that I was able to clean the foam stopper. Especially after a blow off (Before I built my stir plate) What is the proper procedure for cleaning a foam stopper? Or are they meant to be disposable?

time flies like the wind, fruit flies like a yeast starter...