Yeast Starter Question

[Beerlust]

Hi guys.

 

Rather than start a new thread, I thought I'd post this question here.

 

I've had a successful starter of US-05 sitting out on my kitchen benchtop under ambient conditions for almost two weeks now. It's sealed with foil & has been wrapped in a towel the whole time. It looks fine & smells ok. No noticeable signs of any infections or bacteria present.

 

I never normally do this with a starter, but for a number of reasons my next brewday just kept getting pushed back further & further.

 

Can anyone see a reason or does anyone know of a reason why I shouldn't pitch this into a brew?

 

All thoughts welcomed.

 

Cheers,

 

Lusty.

[Otto Von Blotto]

It probably would have been better to keep it in the fridge after the first few days rather than leaving it at ambient, but, if it smells fine then it should be ok. You could tip a small amount into a glass and taste it too if you like.

 

Given this is the case I can't see why you couldn't pitch it into a brew... in effect it's not a lot different to storing a harvested portion and pitching that into a starter.

[dragit]

Sorry to bump an old thread, just had a quick question about this…

 

I did a brew yesterday, but today realised that I had probably underpitched using only one satchet of yeast… so I wanted to try some of the yeast that I had collected from a brew from around 6 weeks back, but after some reading I chickened out as a few articles suggested that two weeks should be the maximum length that yeast can be kept before it becomes ineffective.

 

After spending half a day brewing I really didn't want to screw it up by using dud or infected yeast for the sake of $5… so I threw in a second sachet this time around.

 

So, my question…

 

How long do you keep recycled yeast before re-pitching?

 

How long is too long?

[ChristinaS1]

There is no hard and fast rule about that. Wyeast says seven to ten generations, but a lot depends on sanitation. Before using slurry, smell it to make sure it has not become infected / smell off. Always have some dry yeast on hand that you can use instead, just in case it does (Plan B).

 

Kit brewers don't do a full volume boil, so contamination is more likely to creep in at an earlier stage, especially if you own pets, or brew outdoors, or with the windows open, or with a fan blowing, and in your kitchen. I own pets and brew in my kitchen, sometimes the windows open, or the central heating blowing in winter. As a result I have never ventured beyond three generations (= two repitches), and so far so good; but I am not a risk taker.

 

Edit: just realized I misunderstood your question. Personally I always re-pitch within a day or two, but I have also read the two week thing. That being said, there are plenty of people who store slurry much longer and pitch it without making a starter, with apparently good results. Again, that is probably safer if you have done a full wort boil and are starting out with a sterile wort, in which case a long lag time is not so much of an issue.

 

Cheers,

 

Christina.

[Otto Von Blotto]

A full volume boil doesn't guarantee a sterile wort. If it did then this stupid botulism with no-chilling nonsense wouldn't still be doing the rounds... , and besides if it is exposed to air before pitching the yeast which it always is, then that alone renders it contaminated even though it's to an extremely small degree which the yeast can easily take over.

 

If you're harvesting yeast from starters rather than fermenter trub then it doesn't matter how the batch wort is created either because the harvest isn't coming from there. Starters are usually boiled before being cooled down to pitch the yeast, much like a full size batch in that regard.

 

Anyway, you can keep yeast in the fridge as short or as long as you like. Bear in mind that it will lose viability over time (i.e. some of the cells die), but it is *probably* at a lesser rate than the yeast calculators would suggest. In fact, while they probably suggest that the yeast lose viability more quickly than they do, they actually suggest that the yeast never completely dies either, because they work off a calculation of it losing 20% or so viability every month. It's not done like 80% at one month and 60% at two etc., it's 20% of what's left... so after one month it's 80%, but then the next month it loses 20% of that 80%, and so on, and if you keep going down at that rate you'll never actually hit zero.

 

I'm going to be doing some testing on this viability myself now that I have a microscope and viability stain set up. I did a practice run last week with some yeast from the batch that was in there and measured about 85-90% viable cells. My next one will be with a 1469 culture that has been in the fridge since February. I'm also ordering some Trypan Blue to use with it as it is considered a more accurate stain than the widely used methylene blue stain.

 

Cheers

 

Kelsey