Yeast Starter?

[Eddie90]

Hi all

I am planning to make a relatively high ABV Double IPA. I'll also be using liquid yeast for the first time. The batch will, hopefully, be 23L in the fermenter with a target OG of 1.073. If I were to just add the standard smack pack into this would I be under-pitching? Or would this be ok?

Also, since this is my first go, would most people advise on getting dried yeast too? Or is it relatively straight forward?

Cheers,
Eddie

 

[Galena]

According to my calculator (Homebrew Dad's Yeast starter calculator) you will need 408 Bn cells for that. The standard pack is 100Bn so you would probably want to make a 2 step starter to get it somewhere in that region. So for example 150mls DME in 1.5 litres water for the first step will give 245 Bn, then step 2 with 200grams DME in 2 litres would build it up to 527 Bn. This would also give you 100Bn extra to store for the next time if you are so inclined.

 

[cushyno]

You could make a smaller batch to begin with, say, 15l of session strength ale with one pack. The yeast will be happy and not stressed. Then brew your DIPA and pitch the slurry from the first batch.
That way you get more beer and it acts like a starter.

 

[Eddie90]

Cheers guys. This is what I found quite confusing. If people use the slurry as their yeast, how do you know how many active cells are in there? Also, how many times can slurry be used again? Is it just the once?

 

[cushyno]

From what I've read it's fairly common practice when brewing a big beer that needs lots of healthy yeast to brew a lower ABV beer to grow enough yeast first.
Provided your first batch hasn't been dry hopped and the wort going into the FV was fairly clear of hop and grain debris, the yeast slurry will be very usable. You can estimate roughly the number of cells. It does vary from each yeast strain to the next, though a middle of the road guide is that yeast slurry with some trub (debris) will be around 1bn cells per 1ml of slurry.

I usually work on 750ml of slurry from a beer that had OG of 1.050, though it varies from yeast to yeast. Nottingham packs down tight so I get less slurry, maybe 600ml. CML Kolsch is much looser. SO4 is somewhere in between.

For me, 750ml gives approximately 750bn cells as a rough guide. Saving 1/3 of this in separate jars (complete with a little of the remaining beer) should give 250bn cells. By the time I re-pitch several weeks later I expect to have lost a few % as some of the yeast die off. However, 214bn cells is enough for a 1.050 23l batch. +/- 20% either way isn't going to make too much difference so I throw in one of my saved jars. If the yeast is older, like a couple of months older, I may put a jar into a 1l starter just to be sure.

So, my reasoning for building a lower ABV beer as your starter - 15L of 1.045 wort with a healthy and stress free fermentation should give you enough for around 400-480bn cells. Right in the ballpark that @Galena suggests and if you bottle the smaller batch the day before you need the yeast and leave the yeast sat in the FV for the next day it will be as healthy as can be. Just take care to keep the lid on the FV closed as much as possible as you don't want any bugs getting in.

The slurry can be re-pitched several times like this, but generally received wisdom is that 5-6 times is the safe limit before yeast starts deforming. Some brewers continue to use their slurry for many times more but the yeast may take on a different character. The other way is as Galena describes is to work with starters. Overbuild your starter and save a portion of it to build up next time. Because you take absolute care to be sanitary with your starter and the yeast never gets stressed, theoretically it's possible to continue to overbuild-save-overbuild-save indefinitely.

 

[RGeats]

From what I've read it's fairly common practice when brewing a big beer that needs lots of healthy yeast to brew a lower ABV beer to grow enough yeast first.
Provided your first batch hasn't been dry hopped and the wort going into the FV was fairly clear of hop and grain debris, the yeast slurry will be very usable. You can estimate roughly the number of cells. It does vary from each yeast strain to the next, though a middle of the road guide is that yeast slurry with some trub (debris) will be around 1bn cells per 1ml of slurry.

I usually work on 750ml of slurry from a beer that had OG of 1.050, though it varies from yeast to yeast. Nottingham packs down tight so I get less slurry, maybe 600ml. CML Kolsch is much looser. SO4 is somewhere in between.

For me, 750ml gives approximately 750bn cells as a rough guide. Saving 1/3 of this in separate jars (complete with a little of the remaining beer) should give 250bn cells. By the time I re-pitch several weeks later I expect to have lost a few % as some of the yeast die off. However, 214bn cells is enough for a 1.050 23l batch. +/- 20% either way isn't going to make too much difference so I throw in one of my saved jars. If the yeast is older, like a couple of months older, I may put a jar into a 1l starter just to be sure.

So, my reasoning for building a lower ABV beer as your starter - 15L of 1.045 wort with a healthy and stress free fermentation should give you enough for around 400-480bn cells. Right in the ballpark that @Galena suggests and if you bottle the smaller batch the day before you need the yeast and leave the yeast sat in the FV for the next day it will be as healthy as can be. Just take care to keep the lid on the FV closed as much as possible as you don't want any bugs getting in.

The slurry can be re-pitched several times like this, but generally received wisdom is that 5-6 times is the safe limit before yeast starts deforming. Some brewers continue to use their slurry for many times more but the yeast may take on a different character. The other way is as Galena describes is to work with starters. Overbuild your starter and save a portion of it to build up next time. Because you take absolute care to be sanitary with your starter and the yeast never gets stressed, theoretically it's possible to continue to overbuild-save-overbuild-save indefinitely.

I am planning on doing similar in a week or so, the first beer is fermenting happily at the moment. A question im not sure about is if you are putting a new wort right on top of the trub should you use all the trub or only about 1/3 of it as you suggest above?

 

[cushyno]

It depends on the second beer. I've done both in the past. Only pitched onto the whole yeast cake twice, once was fine, second time I had a sort of plasticky taste to the beer. Both first batches were best bitter style, both second batches were brown ales to the same recipe. From then on I've always only pitched 1/3 to 1/2 of the yeast cake and save the rest in a jar (or ditched it if I didn't want to save).

When re-pitching from a jar, or even straight onto the yeast cake, make sure the yeast is at the same temperature as the wort within a couple of degrees. For jars removed from the fridge, give them a few hours to stabilise at room temperature, same as you would with a sachet of dried yeast. Also it seems best to pitch most ale yeasts into wort a couple degrees lower than fermenting temperature and let them free rise to the correct temperature through their growth phase. I can't say about lagers as I've only brewed one and not read up enough on them.

 

[RGeats]

Great thanks that's really interesting information. I think I'll just use around a third of the yeast cake. I guess it's best to make sure the wort is well aerated when reusing yeast.

 

[cushyno]

Yes, well aerated. Sometime I'm going to try putting some of the old yeast in the boil too, it kills it off and then it apparently it acts as a nutrient.

 

[cushyno]

Just search for "Yeast nutrient" plenty of posts on this subject come up. Here's one: Yeast nutrient, needed?

 

[Eddie90]

Thanks @cushyno, much appreciated!