Idetifying a gone off yeast starter

[MrN]

I'd harvested some Wyeast 1469 from a previous brew, a few months ago, from the bottom of my mini keg. I built it up with small starter in a mason jar and then stored it in the fridge. I'm hoping to reuse it next week in a Landlord clone and have just decanted the old starter off the top of the refrigerated yeast to start building it up again.

I've kept some of the decanted old starter to taste if it's still ok. Is it normally quite easy to tell if yeast has gone off? Are there any tastes or smells I should be looking for? I don't want a ruined batch!

[BrannigansLove]

I've never bothered tasting old starters for yeast viability. My suggestion would be to build a small starter, and if it takes off, I'd say you're good.

[AnthonyUK]

Do you know what a good yeast starter will taste like?
As you are getting the yeast to multiply at temperatures around 25°c the result is going to be much different than when fermenting.

[MrN]

Do you know what a good yeast starter will taste like?
As you are getting the yeast to multiply at temperatures around 25°c the result is going to be much different than when fermenting.

I guess this is why I was asking. I did taste the starter when I used the yeast first time round, just tasted like unhopped beer, except a bit more fruity/yeasty.

What I poured off after taking it out of storage was similar, quite light but with a stronger yeast flavour than normal beer. What I'm wondering is if it's normally obvious when a batch of yeast has gone bad (e.g. like when you taste gone off milk, you know straight away)?

[Fil]

The yeast wont go off as such, and as long as they revive from dormancy you should be good to go. the risk your taking is that the yeast you stored may have been stressed and may have undergone a viable dominating mutation, and if so the mutated yeast may not behave as the original strain did.

im no bioligist/chemist so only have a lay understanding of the subject, but 1x harvest/store/regrow cycle may stress the yeast enough to stimulate a viable mutation but its not very likely, If the yeast had undergone 10x such cycles then perhaps the chance of a viable dominant mutation MIght be high enough to warrant caution, But Imho your probably on a safe bet with it for now.

Folk who bank yeast on slants will take the time to streak a plate of yeast to isolate colonies of yeast so visual checks on colony symmetry and colour can be used to eliminate some mutated colonies which is about the limit we can achieve at home..

brewing is a gamble, just a gamble where we stack the odds in our favour as much we can

[Bad 'Ed]

FYI, a vinegary smell is not an indication of an infection in a starter. The first time I used WLP002 I made a starter but ended up chucking it and pitching dry because it smelt so strongly of vinegar. The second time I used WLP002 it smelt again (although less strongly) but I used it anyway and everything turned out well.