Liquid yeast shelf life

[daphatgrant]

Hello everyone, I'm still relatively new to home brewing with about 20 batches under my belt but I've started to notice a consistent "issue" with my beers. I keep getting an odd lightly sweet aftertaste in my beers, especially noticable in IPAs and other light ales. I've tried lowering my fermentation temps and am still getting it, 62F for the last IPA I made. I've been using US-05 pretty much exclusively and want to try something else out to rule out the yeast. I'm thinking about trying either WY1056 or WLP001. I'm wondering how long on average you can keep a yeast pack in the fridge? I know it'll depend on how old it is when you get it but I'm assuming a couple months is good? I've got US-05 that's good till next year but I know that dry yeast is a different animal. Thanks for any input, I got discouraged on the last batch but want to get back into it.


TLDR:
Going to try different yeast to rule out flavor "issue"
On average how long do you keep liquid yeast in your fridge?

 

[VikeMan]

There is really no average for how long liquid yeast is "good." Best By dates are practically useless. It's all about how many viable cells are in the package and how many cells you need/want for a particular beer.

Some things that influence how many viable cells are in the package:
- starting cell count
- age of the pack
- how the pack was handled and stored

Some things that influence how many viable cells you need:
- Batch Size
- Original Gravity
- Beer Type (e.g. lager vs ale)
- Brewer's goals/preferences for the beer

Yeast Calculators are really, really helpful with most of the above.

 

[Fhizzicks]

Another thought is could this be oxidation? I've had NEIPA present a honey-like sweetness before turning purple before. What is your packaging procedure like, and could excess oxygen be getting in?

 

[1HW]

Yeast Calculators are really, really helpful with most of the above.

What @VikeMan said. Once you have your recipe planned out, you should use a yeast calculator to determine whether the yeast (given their current age) are up to the task of fermenting the batch as designed. Generally, what you will find is that the calculator recommends using a starter (i.e., a day or two before you brew, you pitch the yeast into a certain amount of dry malt extract (DME) mixed with sanitized water to allow the yeast a chance to reproduce).

 

[daphatgrant]

Thanks for the responses guys! I did end up ordering a couple vials of WLP001 for a couple IPA's I'm going to try making next week. The 3rd one I ordered as a back up/next batch.

There is really no average for how long liquid yeast is "good." Best By dates are practically useless. It's all about how many viable cells are in the package and how many cells you need/want for a particular beer. Yeast Calculators are really, really helpful with most of the above.

Haven't ever looked at them before, I'll be checking them out, thanks for the info!

Another thought is could this be oxidation? I've had NEIPA present a honey-like sweetness before turning purple before. What is your packaging procedure like, and could excess oxygen be getting in?

I wouldn't imagine so, I do oxygenate the wort with a wand just prior to pitching but beyond that the only other time it should see oxygen is if dry-hopping. I also use a CO2 harvester/airlock. I do a closed transfer to get it into my kegs and purge the keg with CO2 before the transfer. Color and clarity has always been what I expected as well. I had been fermenting at 70F which I was told was too high but the last batch was fermented at 62F and I had the same sweet flavor. I've got the same flavor across different IPA's with different grain/hop bills so I've been trying to narrow it down. I filter my water as well.

You should use a yeast calculator...

Thanks for the link! I do have a stir plate and flasks so I've got the equipment to do it. So far the US-05 has always taken off so I haven't felt a need to create a starter yet.