Making more yeast

[Cadbury]

G'day men,
I have a packet of ale yeast and was wondering if I can turn that amount of yeast into more yeast(say 3 times as much) I've farmed the yeast from the fermenter before, but I was wondering if I can multiply what I have from the dried stage?
Cadbury

[warra48]

Technically it can be done.

I think all you need to do is to re-hydrate your dried yeast, and then pitch it into a starter of say 2.5 to 3 litres.
Aerate it well, or use a stir plate.

I don't have a stir plate, but I aerate my yeast starters for about 3 to 4 hours with an aquarium pump (I use just the silicon hose, not the airstone).

Here's a picture of the end result of one of my yeast growing starters, although admittedly it was from a Wyeast smackpak:

[Bum]

I'm looking into splitting my next Wyeast smack pack and have been reading up on the process but can't find any pics of what each final amount should look like. Going from your picture as a starting point for the question - should I be draining off the beer above and dividing up the yeast cake below? Or should I be mixing that cake up with a small amount of the beer and just bottling that?

[warra48]

The batch I photographed is from a smackpak of WY1469 I built up into a starter, and decanted into several splits.

The brown stubby is one of those splits. I used the slurry from that to build up the starter in the 3 litre bottle. I normally do it in two or three stages. I first add the slurry from the stubby to ½ litre of wort, ferment it out, chill and decant the beer, add another 1½ to 2 litres of wort to the slurry residue in the 3 litre bottle. That's the result for an ale yeast, and is what's pictured in the photo. I pitched the entire amount of the slurry into my 23 litre batch.

For a lager beer, I do yet another step by chilling and decanting the starter beer, and adding 2 to 2½ litres more wort. I like to pitch my lagers cold, so I make sure I have sufficient yeast to do that.

I never pitch the starter beer itself, only the slurry into the actual beer.

[Bum]

Excellent! That does clear up some questions I had. Thanks.

I'm still slightly unsure about the first split of the original pack, however. The last step in all tutorials I've found so far just end with something like "Divide into stubbies and refrigerate". I'm planing on pitching the wyeast into 2lt-ish of 1040 wort in a 3lt bottle, fermenting out, then splitting but I can't work out if the yeast needs beer on top as some sort of protection for longer-term storage or not or if I need to be bottling the yeast as purely as possible.

Sorry for the derail, Cadbury, but I hope these answers end up being useful for you too.

[warra48]

This is what I do. It is not necessarily the only or the best way, but it works for me.

I decant enough of the starter beer to leave me sufficient volume to fill 4 or 5 250 mil stubbies. I then swirl the starter bottle to suspend all the yeast, and pour that into my stubbies to about 80 % capacity. I cap them with a crown seal, and store in the fridge until needed.

Alternatively, you could pour off all the starter beer, and add some boiled and cooled water back and swirl the starter bottle. Pour this into your required number of starter stubbies in equal volume (or tubes etc, whatever you use), and top up with more boiled cooled water. Cap and store in fridge until needed.

The stubbies are then used to make a fresh starter.

It goes without saying you need to be careful with your sanitation in this whole process.

[Bum]

Naturally. That's a big help, Warra. Thanks, yet again!

[Cadbury]

Thanks for that ----- I think!
Cadbury

[Bum]

PMed. Sorry for what looks like a derail but I think it is all on topic.

[chadjaja]

I make a starter out of all my smack packs on a conical on my stir plate. I let it stir for about 36 hours till done and then pour the milky wort into 4-5 small 250ml plastic bottles and put them in the fridge. I then step up a bottle per brew in the conical on the stirrer again a few days before brew day, chuck it in the fridge for 24 hours or more, decant most of the oxidised beer and pitch the yeast at room temp.

I did this on Tuesday afternoon and it took off in just a few hours and I have great fermentation and results. You just have to be very clean about the whole thing. Makes my yeast pack last 5 brews or more if I make up multiple generations.

[melykabeer]

Great info here thanks
I have 1 question, when making your starter will it do any harm to the yeast by letting it ferment at room temperature 30'c? I was planning on trying this for a 1 pack of safeale turning it into 5

[chadjaja]

Ideally you ferment out the starter at the temp you want to brew at. Sure the starter ferments out faster at a higher temp but you don't get the sort of strong yeast cells you want out of it. Better to stick to the temps you brew at for 05 being 16-22 for me.

[drsmurto]

I will put my hand up to disagree with you Chadjaja.

I keep my starters at 25-30C as that is a much better temperature for the yeasts sex life. Yes, it ferments faster and produces some off flavours but the amount of yeast produced IMO is greater and by chilling and pouring off the 'beer' and pitching only a the slurry you aren't introducing the off flavours to your beer.

[chadjaja]

I've read although it does make more cells the wall of the cells or something like that are more prone to rupture and the like and therefore its better to go for quality over quantity. I too decant the liquid as anything on a stir plate is going to be oxidised.

From Mr Malty that I took a lot of info about starters from.

Warmer starters (up to 98°F, 37°C) equal more rapid yeast growth, but using these very high propagation temperatures negatively affects the viability and stability of the resulting yeast. Very rapid growth or excessive growth can result in weaker cell membranes due to lower unsaturated fatty acid concentrations. Lager yeasts tend to be especially sensitive to high temperatures.

The cooler you ferment the starter (down to the planned fermentation temperature for the main batch) the slower the yeast growth, but the yeast can be healthier than yeast coming from a high temperature starter.

Keep starters between 65°F (18°C) and 75°F (24°C). A temperature around the low 70s (72°F, 22°C) strikes the best balance for the propagation of yeasts. Lager yeast starters can be kept a few degrees cooler and ale yeasts can be kept a few degrees warmer, but this temperature strikes a good balance of yeast health and efficient propagation for both types of yeast.

[drsmurto]

I think pushing the starter up to the mid to high 20s is very different to 37C.

Its the middle ground between ideal ferment temps and ideal yeast sex temp. So i guess i agree with you to a point. I don't go to too much effort to monitor the temp of my starters, the heat generated by the stir plate seems to keep them in the 26-28C zone, occasionally nudging 30C if i have the speed on too high! The sight and sound of a vortex in my 6L flask is porno to this chemistry nerd

re - oxidation in a starter. The yeast consumes O2 as part of the lag/growth phases. Once the O2 is depleted they switch to fermentation. Stirring does not introduce O2 back into the start unless your flask doesn't have a lid and even then, the positive pressure produced by the CO2 released during fermentation will push any 'air' out of the flask. So the starter isn't oxidised as far as my understanding of the process goes. The physical act of stirring keeps all the yeast in suspension negating the need to shake your starters as often as you can.

Cheers
DrSmurto

p.s. re-reading your Mr Malty quote i note he says that a few degrees higher than ideal (18-24) is fine. So 26-28 is not unreasonable. 30 is getting up there so maybe i should be taking a reading of the actual temperature of my starter...... Hmmm, food for thought.

EDIT - have a read of this Chadjaja - Yeast Life Cycle in Brewing Beer

[chadjaja]

Ahh thanks Doc, good read and absorbing it all

I've got a few flasks now and they go in front of the TV like a lava lamp..

I just pitched a batch of 1056 into my second batch of Golden ale just half an hour ago. First keg lasted 3 days when word got out Hit ALL my temps and goals and it should be bubbling away shortly