Yeast Stores Gone Vinegary

[floppinab]

I've been keeping yeast stores pretty much following this method

http://www.aussiehomebrewer.com/forum/inde...?showtopic=1434

for the last six or so months. I haven't gotten around to using one yet but cracked one open this morning.

There is a mild but signficant vinegar odour coming from the bottle. They've been stored in old 600 ml Gatorade bottles in the fridge since decanting off the original starter. I checked a few of the other bottles I've got stored and they have a similar odour. The bottles had a good soack in napisan and a decent sit in iodophor no rinse. I've got no reason to suspect any infection issues.

Anybody had similar experience and more important will the yeast be OK to use???

 

[DJR]

How old are the yeasts Gav? Might just be a little too old really, i reckon once you've split they're only really good for a couple of months, then you have to reculture them.

Good yeast samples should have a slightly sweet smell i find, just like a freshly opened Wyeast packet.

 

[Batz]

I've been keeping yeast stores pretty much following this method

http://www.aussiehomebrewer.com/forum/inde...?showtopic=1434

for the last six or so months. I haven't gotten around to using one yet but cracked one open this morning.

There is a mild but signficant vinegar odour coming from the bottle. They've been stored in old 600 ml Gatorade bottles in the fridge since decanting off the original starter. I checked a few of the other bottles I've got stored and they have a similar odour. The bottles had a good soack in napisan and a decent sit in iodophor no rinse. I've got no reason to suspect any infection issues.

Anybody had similar experience and more important will the yeast be OK to use???

Have a sip of one,that'll tell you all you need to know.

Batz

 

[floppinab]

They're around 6 months old, but I was under the impression that they should be OK for a good 12 months.

Hmmm, let's say if something has got into the liquid, the yeast that had settled out earlier should still be OK??.......maybe!!!!!! Then the main issue would be to try and isolate the yeast as much as possible when starting her up again???

 

[pint of lager]

Hmmm, let's say if something has got into the liquid, the yeast that had settled out earlier should still be OK??.......maybe!!!!!! Then the main issue would be to try and isolate the yeast as much as possible when starting her up again???

If the vinegary aroma is due to decomposition of the yeast, then you are fine to use the yeast slurry and step up again.

If the vinegary aroma is due to an infection, you are 100% gauranteed to infect the next batch. The only way to separate the infection from the yeast is via plating on agar.

 

[floppinab]

Thanks pol. I'll try culturing one up. My guess is I'll know pretty quickly if there's an infection in there that I can't get rid of.

 

[floppinab]

Thanks pol. I'll try culturing one up. My guess is I'll know pretty quickly if there's an infection in there that I can't get rid of.

OK, Yuck I've got a nice little Acetobacter culture if anyone wants one

 

[NRB]

You picked that in 3 hours?!

 

[andreic]

Hi,

I've followed a similar method with liquid yeasts. I have tried a few Whitelabs yeasts, grown them up in 2L of dme wort at 1.040 and bottled 5 stubbies worth and put them in the fridge and then stepped up the remainder for the first batch. This was very successful until recently... I had a few WLP008 East Coast Ale yeast starters from 9-12 monthold stubbies that had a distinct cidery/vinegary taste. I used one in a kit beer, but for one of my first few AG brews I decided not to take the risk and chucked the starter and used US-05 american ale instead. The kit beer tastes pretty ordinary, but I'm not sure its entirely due to the yeast. I've also done a couple of AG hefeweizens with WLP300 yeast starters from yeast stubbies of this method. They are good beers, but the starters also had a hint of vinegar and I'm starting to think the yeast was not in optimal condition and the beers could be better...

I am considering alternate methods of storing yeast in future. There are a few discussions on this site which describe simply splitting the liquid yeast into vials and storing these in the fridge. I will do this next time I get a liquid yeast and see if it is better.

cheers,

Andrei

 

[pint of lager]

No matter what method you use to split and store yeast, there are risks of infections.

The smaller the amount of yeast, the greater the risk.

Infections and wild bacteria multilpy at 10 times the rate of our wanted brewing yeast. So if you start with very few live yeast cells, it can be quickly over run by an infection.

Also, many of the bye products produced by infections and wild yeast are readily detectable, meaning that only a very small amount is needed to spoil your beer.

Yeast stored, dies off quickly. So you may have originally stored a few desertspoons of prime yeast, after 6 months, you may have a pinhead of live yeast left. This small quanity has to be very carefully stepped up to quantities that will successfully start a brew.

A common problem with infected brews, they taste fine after the final sg is reached, then over a few weeks/months, they start becoming overcarbonated and taste sour and dry. This is because you have a minor infection that is slowly working through the long chain sachaarides (brewing malts) not utilised by your pitched yeast.

There are some excellent dried yeasts available. Keep a few sachets in your fridge. With your starter, if in doubt chuck it out. Pitch your dried yeast.