Yeast Question

[VaNewbieWRB]

I ordered a vial of WLP039 Midlands Ale Yeast. I'm going to use it in a 2 gallon extract stout. I made it last year and it was good, but I think it can be better with a top shelf yeast. My questions are these.

1. For a 2 gallon batch, can I just pitch 1/2 of the vial as opposed to all of it? It says to pitch 1 vial for a 5 gallon batch.

2. If I do only use 1/2 of the vial, can I just cap the vial and keep the unused portion in my fridge?

As always, thanks for your help.

 

[bransona]

If you make a starter, half of that pack will absolutely be enough. I'm generally one to use dry yeast though (broke college student life), so I'm unsure about shelf-life.

https://www.homebrewtalk.com/showthread.php?t=86725

That thread mentions people splitting the pack, starting all of it, and just hanging on to the other starter. Also mentions shelf life is usually 6 months, but I don't know how that will change after it's been exposed to open air.

Good luck!

 

[brew_darrymore]

I ordered a vial of WLP039 Midlands Ale Yeast. I'm going to use it in a 2 gallon extract stout. I made it last year and it was good, but I think it can be better with a top shelf yeast. My questions are these.

1. For a 2 gallon batch, can I just pitch 1/2 of the vial as opposed to all of it? It says to pitch 1 vial for a 5 gallon batch.

2. If I do only use 1/2 of the vial, can I just cap the vial and keep the unused portion in my fridge?

As always, thanks for your help.

I would make a starter with the full vial. Once the starter is done, cold crash the starter by leaving it in the fridge for 24-48 hours. Decant the spent wort, and use a small part for your brew and keep the rest of the yeast for future use.

Using http://www.brewunited.com/yeast_calculator.php and assuming you're making a 2-gallon average gravity ale (OG 1.055) and being conservative assuming your vial is not that fresh (September 2015), I came up with the following figures: Make a 1.5 litre starter of 1.04 gravity. You'll end up with 278 billion cells. Your 2-gallon batch needs 77 billion, and you'll have 200 billion leftover for future use. According to the calculator, use 420ml (77 billion cells) of your starter for your batch, and the remaining 1079ml (200 billion cells) you can save for future use.

 

[slym2none]

I get the feeling he is talking about not making a starter at all...

 

[Qhrumphf]

Don't make a starter. But pitch the whole vial.

That'll put you about where you need to be. 1 vial per 5 gallons is almost always a substantial underpitch, often requiring twice that amount of yeast.

If the yeast is super, super old, or if your stout is incredibly high gravity, that may still not be enough though.

 

[IslandLizard]

Use the yeast calculator and you'll see how many cells you need vs. how many cells are in your vial. Depending on the freshness of the yeast, for a 2 gallon batch the whole or a partial vial may suffice. If it's over 3 months old, one vial may still be barely enough.

There are a few good reasons to make a starter a few days ahead. One is to grow a larger starter than you need, and save the leftover in a mason jar in the fridge for a next brew. When that day comes, make a new starter with what you saved, also a bit larger, save the excess, and so on. That's called yeast ranching. Good sanitation practices are needed of course.

 

[Calder]

Assuming it is not old yeast, just use the whole vial and you should be good.

If you wish to use some off the yeast for another batch, collect the slurry in a sanitized mason jar and store until needed. Then use about a third for a batch of the same size and gravity.