Yeast Starter

[Yob]

Hello all, Im going put down my third CPA Kit brew (this time after the hot weather has passed)... this time I want to use a Yeast starter made from CPA Stubie dregs to get the right flavour.

My questions are:

How much liquid do I need for the starter? - (Ive got about half a stubie collected thus far)
How long do I leave the yeast in - (about half an hour I believe? using a US-05 type)
Any other tips?

Cheers all!

 

[Wolfy]

You should get enough yeast to grow a starter from 1 longneck or 2-3 stubbies.
Let the bottles sit for a while so that the yeast settles to the bottom, sanitize everything you'll use, then collect just the dregs from the bottom each bottle after carefully pouring out (and drinking) the rest. You only need to collect the last little bit where you should even see the settled yeast.
Once you have collected the small amount of yeast from the bottle, you can then grow it and step it up (read other threads on how to do that).

I'm not sure what you mean or are asking about leaving the yeast in or using a US-05 type - but I'd suggest you use the search function and follow the suggestions made in the very detailed threads about cultivating your own starter from Coopers bottles.

 

[BjornJ]

As Wolfy says, you don't need a lot to start with, then you let this yeast grow/multiply in a starter bottle.

You boil dried malt extract in water to create the wort to let the yeast grow in.
Boil 100 gr of Dried Malt Extract in 1 litre of water for 15 min in a glass bottle of some sort with some alu foil over the top of the bottle.
Spray the outside with sanitiser and let it cool down.

When at room temperature, you want your yeast to grow into this wort, but probably not start with the whole litre. So you need another bottle, say a 1.5 litre soda bottle (sanitised) with half a dl of the sanitised, cooled wort. Tip the yeast from the Coopes stubbies in the bottle with the fresh wort and shake the shit out of it. Now you shake it as often as possible and add sanitised wort whenever you have time. Over 1.5-2 days you want to step up to the whole litre. This allows the yeast to grow nice and steady, and the shaking add oxygen which will allow them to grow better, but make the beer in the bottle smell sour.

When you are ready to brew, you simply leave the bottle of starter on the kitchen bench for several hours. When ready to pitch the yeast you pour off most of the "beer" and keep the yeast slurry in the bottom of the bottle, give it another good shake and pitch this in your fermenter.

If you want to get fancy, you build your own magnetic stirrer from old computer parts, this creates literally 10-15 times the amount of yeast cells..

stir plate: http://www.stirstarters.com/instructions.html


If you want to read more about what really goes on and why you should be making starters, this is a loong but very educational read:
http://www.maltosefalcons.com/tech/yeast-p...s-and-practices

thanks
Bjorn

 

[manticle]

Sounds odd. You are soaking a yeast strain in a second yeast strain to get the flavour of the second yeast strain in the first. Why not just use the second yeast strain? What you are doing with the bowls and water is 75% of the way towards having a proper starter with the cooper's yeast. All you need to do is add dried malt extract and wait a bit longer.

 

[Yob]

AAAAAhhhhh!! My cloud of confusion lifts!! Cheers will get that going, 1 Question remains, when stepping up the yeast.. all done at room temperature I presume?
I must say my last one was a joy.. but I just think it could be better yet... trying to refine/improve methods is a challenging task.. as is perfection!!

 

[Yob]

Not until Manticle put it like that the penny dropped, I hope this is the point.

The yeast collected from the dregs is not ALL dead, and the trick is in fact GROWING the survivors back into significant numbers to go again? and therefore getting more of the original taste...

S@#T I hope this is the theory otherwise I shall be very much confused.

 

[Melthar]

Sort of.

It's not so much that some of the yeast is dead in the bottles, it's that there's not enough of it for a full batch.

So yes, you're growing numbers up so you have enough. (hence the malt, and the oxygenation)

 

[manticle]

Not until Manticle put it like that the penny dropped, I hope this is the point.

The yeast collected from the dregs is not ALL dead, and the trick is in fact GROWING the survivors back into significant numbers to go again? and therefore getting more of the original taste...

S@#T I hope this is the theory otherwise I shall be very much confused.

You're understanding is correct.

As for temperature - well you can do it a number of ways.

You can ferment hot to make it quicker. In that case ferment it right out, pour off the fermented beer and use some boiled cooled water to mix up the slurry (will look like your fermenter at the end of a brew). Whisk/aerate your wort, pour in the yeast slurry and seal her up. You can use a stir plate - I'm assuming you don't have one (me neither). The reason you would discard the beer at the top is because the warm ferment will bring the associated flavours to your brew.

Or you can do as I do - ferment at fermentation temp and when you see a good amount of krausen, pitch the lot into the brew. However you may need to step up the yeast which involves making a 1 litre wort (1 litre water, 100g DME), letting that ferment right out, then adding another litre and 100g DME, letting that ferment etc until you have the number of cells you need. Mr Malty pitching calculator will let you know how much you need. 1 Litre should be enough for an average 1040 brew but if you are making strong beer you will need more.

My understanding is that no matter what you start with, the amount of cells left at the end of fermenting 1 litre of 1040 wort (regardless of what was there to begin with will be within a certain range and therefore calculable. I hope I have that correct.

I realise some of that may seem technical and complex and it is worth reading and developing a better undertsanding of what's happening (I still am) but making a coopers starter is really quite simple. Good article found here: http://www.aussiehomebrewer.com/forum/inde...;showarticle=40

 

[JestersDarts]

My understanding is that no matter what you start with, the amount of cells left at the end of fermenting 1 litre of 1040 wort (regardless of what was there to begin with will be within a certain range and therefore calculable. I hope I have that correct.

I hope so too... for my understanding-sakes!
can someone confirm this?

 

[[email protected]]

I hope so too... for my understanding-sakes!
can someone confirm this?

Essentially yes. But not quite. If the starter is well oxyenated the yeast will feed aerobically and reproduce at a constant rate. The more sugar the more they grow. However if you fail to keep your starter oxygenated then you will get anaerobic fermentation which will lead to yeast consuming sugars without reproduction and less yeast in your starter.

 

[Dazza_devil]

What's the real deal with post-fermentation oxidation as far as yeast health is concerned?
From what I've read, oxidation of the wort post-fermentation can stimulate the yeast into using up any particular food reserves it has stored, is this true? What are the consequences?

 

[[email protected]]

What's the real deal with post-fermentation oxidation as far as yeast health is concerned?
From what I've read, oxidation of the wort post-fermentation can stimulate the yeast into using up any particular food reserves it has stored, is this true? What are the consequences?

I'm not an expert on this and this is a partially guessing answer ... but here goes

After fermentation you have only complex unfermentable sugars left. Yeast with oxygen (aerobic fermentation) are more efficiant at breaking up sugars then yeast without oxygen (anaerobic fermentation). So if you add oxygen to the beer after fermentation it encourages the yeast to ferment what they couldn't ferment before. The complex sugars when fermented through aerobic fermentation produce more off flavours when fermented than the simple sugars.

So you have a bunch of yeast swimming round with oxygen ready to reproduce, they eat what ever sugars they can as well as their own energy stores to do this and add some off flavours in the process.

 

[Dazza_devil]

I'm not an expert on this and this is a partially guessing answer ... but here goes

After fermentation you have only complex unfermentable sugars left. Yeast with oxygen (aerobic fermentation) are more efficiant at breaking up sugars then yeast without oxygen (anaerobic fermentation). So if you add oxygen to the beer after fermentation it encourages the yeast to ferment what they couldn't ferment before. The complex sugars when fermented through aerobic fermentation produce more off flavours when fermented than the simple sugars.

So you have a bunch of yeast swimming round with oxygen ready to reproduce, they eat what ever sugars they can as well as their own energy stores to do this and add some off flavours in the process.

So if this is the case, post-fermentation airation will diminish the starter yeast's potential health when pitched into an airated, unfermented wort by using up the yeast's food stores?
Other than that, if you decant off the airated beer from the starter, inclusive of it's off flavours, it poses no other problems?

 

[mjp]

I always use cultured CPA yeast when I make an ale--I do 120g ldme in 1.2 litres water. I boil for 10 mins and then crash cool(sink of ice water around saucepan)til around 22-24C(room temp)I then add the dregs(last inch) of 2-3 stubbies-(Drink from a glass-not bottle).I put this in a sanitised swing top bottle(2$ at your local bargain shop) and leave it in my pantry for 6-7 days. I dont do a small batch first and then step up-I find this gets a 23-25litre batch cracking within 24 hours of pitching.

 

[[email protected]]

I don't really think post-fermentation oxidation to a starter is going to cause much of a problem. I guess it depends on the starter size, and how much off flavour you create. I suppose that if the yeast use up all their energy supplies you could create a selective process for survival of the yeast with the lowest metabolism which may alter the strain of the yeast.

mjp do the swing top bottles act as air locks? thats a good idea. I've been using specially made lids called oztops which have a little oneway valve in them for doing my starters.

 

[felten]

You can just use al foil over the top, not having any top pressure is probably better for growing yeast

 

[Banshee]

Does anybody know if the yeast used in the bottle condition stage is the same strain as the fermenting strain?
I have heard of breweries using a different strain in the bottle conditioning stage. Probably to protect their yeast as it may be unique to them (Coopers).
Anyone?

 

[manticle]

Well documented that coopers bottle yeast is primary strain and if you've ever tasted a beer brewed with it you'd have no doubt.

 

[[email protected]]

Well documented that coopers bottle yeast is primary strain and if you've ever tasted a beer brewed with it you'd have no doubt.

Is there a list of what bottles can be cultured and what cannot? Would be pretty easy to compile from everyones experiance here. I have succesfully brewed with Leffe and Duvel thats all I can remember off the top of my head.

 

[Bizier]

Here is a post by Zwickel on hefes