Yeast starter

[Austy]

Hi guys -

 

I'm sure the topic has been covered before - but because the terminology used is so frequent in the forum, I'm having trouble finding what I'm after...

 

- What exactly is a yeast starter? I assume it's a process involving pre-fermenting or pre-activating yeast?

 

- I've seen people mention that they make their yeast last a long time - how does this process work?

 

- Magnetic stir plates - what is their place in all of this?

 

If anyone knows of any threads that cover this - links please!!? Or if not - I'd be very greatful for any responses to the questions above.

 

 

Cheers,

 

Aaron.

[NorthCoast85]

Hi guys -

 

I'm sure the topic has been covered before - but because the terminology used is so frequent in the forum' date=' I'm having trouble finding what I'm after...

 

- What exactly is a yeast starter? I assume it's a process involving pre-fermenting or pre-activating yeast?

 

- I've seen people mention that they make their yeast last a long time - how does this process work?

 

- Magnetic stir plates - what is their place in all of this?

 

If anyone knows of any threads that cover this - links please!!? Or if not - I'd be very greatful for any responses to the questions above.

 

 

Cheers,

 

Aaron.[/quote']

 

Otto (and I'm sure many others) can help. I'm just starting out on the starter journey myself and I'm glad you've made this post.

 

A starter is basically a mini "beer" made with dry or liquid yeast and wort.

 

The basics are to get a suitable receptacle - usually an Erlenmeyer flask a la breaking bad,

can be found fairly cheap here: http://www.madaboutscience.com.au/store/flasks-erlenmeyer-flasks-c-22_37_107.html?zenid=ssbhqgeo3kqqe91dn7pi9lpuf7

 

Get your flask sterile and boil a measured amount of water and malt, cool to pitching temp and then add your yeast, the yeast multiply and you then have a very nice amount of pitchable healthy yeast cells that you pitch into your main wort. This mini wort can also be split and made into more yeast starters that can be stored in the fridge dormant, making a purchase of one yeast packet or vial very cost effective.

 

This is the limits of my knowledge so far and I'm sure we'll get all the good details from our resident AG brewers.

[Otto Von Blotto]

Hi Austy, I reckon I can probably help here, as I make starters for all my batches these days. My answers are in red. I'll also outline my actual process underneath.

 

Hi guys -

 

I'm sure the topic has been covered before - but because the terminology used is so frequent in the forum' date=' I'm having trouble finding what I'm after...

 

- What exactly is a yeast starter? I assume it's a process involving pre-fermenting or pre-activating yeast?

It's basically a mini unhopped wort, anywhere from 1 to 5 litres. I use LDM and water to make mine, at a rate of 100g LDM per litre of water. Some cats use the actual wort from the batch they're making; I think this is unnecessary in a home brew situation, although it does work well for pitching the starter while active, not so well for harvesting yeast though. Its purpose is to grow enough viable yeast cells to be then pitched into the main batch.

 

- I've seen people mention that they make their yeast last a long time - how does this process work?

I'm guessing you're talking about re-using yeast here. My process for this is to make my starters bigger than necessary, and then pour off a portion (mixed up) into a mason jar, which then goes in the fridge until next time. I just store the yeast under the spent beer, as I have read an interesting article about the detrimental effects of replacing this spent beer with sterile water. I'll find the link.

 

Others harvest from the trub in the FV, but there are two reasons I don't bother doing this. One being it's a lot more faffing about washing the crap from the yeast, and secondly the yeast are arguably more stressed depending on the ABV and hopping in the beer etc. My opinion is that yeast propagated in unhopped, lowish OG wort are more viable and healthy.

 

- Magnetic stir plates - what is their place in all of this?

Basically they keep the wort/yeast mixture agitated, and assist with the exchange of oxygen and CO2 during the fermentation period. The result of this is that the yeast grow more cells than if it was just left to sit still, or only intermittently agitated. And they come in handy to re-mix it all up for harvesting into a jar .

 

If anyone knows of any threads that cover this - links please!!? Or if not - I'd be very greatful for any responses to the questions above.

 

 

Cheers,

 

Aaron.

 

My Process

 

I have 3 different sized Erlenmeyer flasks, 2L, 3L and 5L, for use depending on how big a starter I need. I normally use the 3L for ales and the 5L for lagers. The starters themselves aren't this big, but it helps prevent boilovers on the stove.

 

First up, I use this yeast calculator to determine what size starter I need based on the size and OG of my batch, the number of viable cells I'm starting with, and my aeration method (I use the Troester stir plate setting). Then, I build the starter approx. 800mL bigger than it tells me to, as my harvesting jars are that size, using the aforementioned 100g/L ratio. If the yeast viability is too low, then I will make a smaller starter first, then step it up to the required size.

 

To make the starter up, I simply weigh my LDM in a measuring jug, dissolve it in 1 litre of water, tip this mixture into the flask, then measure out the remaining water into the flask. I drop in my stir bar, then bring the whole lot to the boil on the stove and boil for about 5 minutes. Stove off, let sit for 30 seconds, then fit a piece of al-foil over the top of the flask, re-boil again for another 30 secs, then turn it off and let it sit and cool down naturally (you can chill it faster in the sink if you like, but I'm lazy). I like the flasks because they are designed to be able to be boiled, so I don't have to faff around sanitising them first, or using a saucepan to boil the wort.

 

While all that's going on I will have taken my yeast out of the fridge to allow it to rise to room temp. Once the starter wort is cooled, the yeast is pitched and it goes on the stir plate for 24-48 hours depending on whether it's ale or lager. After the stir plate period I let them sit another day or two, then I stir them all up again in order to harvest the 800mL or so into my jar. After this both jar and flask are put into the fridge. I like to crash my starters and decant most of the spent beer before pitching into the main batch.

 

Next time around I repeat the process with the yeast I've harvested in the jar, and the cycle goes around again and again until I decide it's time for a fresh yeast pack.

 

You can make starters with dry yeast, but make sure you rehydrate it first. It isn't necessary to make starters for dry yeast, but I do it anyway in order to harvest for re-use.

 

Sorry for the epic long winded post, but hopefully you can glean something useful from it!

 

Cheers

 

Kelsey

 

 

[King Ruddager]

For those using stir plates, any idea what rpm they run at? I'm looking at computer fans and about the slowest I've seen is 2,500 RPM while many others are up around 5,000. Is that a big deal?

[Otto Von Blotto]

Absolutely no idea.. I just turn mine up until it gets a small vortex maybe half an inch or a tad more deep in the top of the wort. That's all it really needs. Maybe you can wire in some kind of speed control because all stir plates have controllable speed from almost not spinning right up to "very fast".

 

When Digital Homebrew have them ready I'm gonna grab one of their heated stir plates. These have actual measurements on them of how fast it spins in RPM, and as the name suggests a heated pad that the flask sits on so I can more easily do ale starters in the middle of winter.

 

Dunno if this image will work but this is what it will basically look like... RPM ranges from 200 to 2000.

 

[headmaster]

You do want to be able to control the speed of the stir bar for a few reasons. The most important one is to find a sweet spot where the bar wont spin off the magnetic field. Too fast or even starting too fast can do this, depending on vessel size. I find I can accelerate and go a lot faster in smaller vessels without the bar spinning off.

 

I built a very basic speed controller for mine using a variable voltage regulator wired up like this:

 

https://biohazardbrewery.files.wordpress.com/2013/07/lm317-schematic.jpeg

 

Managed to make mine for about $11, $6, the cost of the plastic box from jaycar and $5 for a couple of stirbars as part of an online homebrew supplies order, and had the other bits in my parts bin at home (LM317 reg, fan, rare earth magnets, power supply, wires, potentiometer, the resistor, and capacitor etc)

 

Another option is to find a variable voltage power supply, some (rare) plugpaks I have seen have a switch on them allowing you to vary from say 2.5v right up to over 12V

 

 

Very useful if you are going to be buying liquid lager yeast and building up a starter big enough to ferment the lager properly. That said I've only used mine once for that, and a few times to mix up some polyclar. After making a giant starter out of some almost expired WLP800 pilsner lager yeast, I have simply harvested large amounts of it from brews, stored in the fridge and re-used.

 

I will be using the stir plate again soon however, as I plan to use some yeast strains that I have harvested and stored in the fridge, but are a few months old now, so they will need refreshing as a lot of cell death will have occurred.

[NorthCoast85]

I'm so glad this thread was made Austy, cheers. Now all my queries are already answered in one handy place.

[Otto Von Blotto]

Here is the thread I referred to in my first post about storing yeast underneath "sterile" water vs. leaving it under the spent starter beer. Sorry, I forgot to look for it yesterday.

[Austy]

I'm so glad this thread was made Austy' date=' cheers. Now all my queries are already answered in one handy place. [img']cool[/img]

 

I'm just the dummy asking the questions! lol

 

Thanks to all the people who have taken the time to help with this subject.

 

I've ordered some flasks - 5000mL, 3000mL and 1000mL. Got all 3 for $88.90 shipped on eBay. I also ordered a 250mL beaker for $5.35 shipped (mainly because I can't help myself when I'm searching for stuff)

 

I don't think I'll buy a stir plate yet... Have to draw the line somewhere or I'll be shot.

 

I might update this threat with some photos of the process, just to clarify that I'm not stuffing anything up.

 

Cheers,

Aaron.

[Austy]

Here is the thread I referred to in my first post about storing yeast underneath "sterile" water vs. leaving it under the spent starter beer. Sorry' date=' I forgot to look for it yesterday. [img']pinched[/img]

 

Great read. Let me get this straight...

 

The process for making a starter is:

 

- Mix up a 1L mini-wort made up at a ratio 100g LDME : 1000mL water

- Boil for 10-15 minutes

- Cover with foil and let cool to around 25C (either naturally, or by running under cold water)

- Pitch sachet of yeast

- Sit at room temp for 2-3 days (and either use a stir plate for optimal grown, or swirl regularly to oxygenate if one doesn't own a stir plate)

- Pitch into batch made up in FV in the same way one would normally use dry yeast

 

Other option:

 

- Make 2-3L batch, and only use around 800mL (give or take) to ferment in the FV

- 'Feed' the batch back up to the 3L mark with 100g LDME : 1000mL water wort (boiled and cooled to same temp as batch prior to adding)

- Store remaining starter at room temp, covered

^^^ Or should the flask be refrigerated?

 

The process for harvesting yeast prior to bottling is:

 

- Swirling the bottom 4-500ml around

- Let it settle for a few minutes

- Decant 300ml or so using the tap into a sterile 500ml flask

- Cover with foil

- Refrigerate for up to one month

- Replenish with fresh wort made up at a ratio 100g LDME : 1000mL water each month if not repitching the yeast into a new batch of beer (to do this, ensure the yeast has mostly settled to the bottom, and tip off most of the solution before topping back up)

 

Cheers,

Aaron.

[Otto Von Blotto]

I'll get back to this thread in a couple of hours when I'm home from work and can more easily type on the computer instead of my phone. It's mostly fine but there are a few things I'd do differently in there.

[Shibby]

I have my first yeast starter to go from Coopers Pale Ale yeast. It finished fermenting on Monday so its been in the fridge for the last few days.

When my brew is ready can I just shake it up and put into the brew once its back to room temperature?

Or do I need too add more LDM and boiled water once cooled to it, to get fermenting again?

Also above 18 its meant to get banana flavours. As this fermented in my pantry Im sure it has a banana smell/flavour. Since its cold crashed should I pour off the top half of the liquid or will I risk loosing to much of the yeast?

[Otto Von Blotto]

Ok, I'm back at the computer now, as per last time answers in red:

 

 

Great read. Let me get this straight...

 

The process for making a starter is:

 

- Mix up a 1L (or 2L or whatever size the calculator recommends) mini-wort made up at a ratio 100g LDME : 1000mL water

- Boil for 10-15 minutes 5 minutes is fine here

- Cover with foil and let cool to around 25C (either naturally' date=' or by running under cold water) Yep

- Pitch sachet of yeast After rehydrating!

- Sit at room temp for 2-3 days (and either use a stir plate for optimal grown, or swirl regularly to oxygenate if one doesn't own a stir plate) Yep

- Pitch into batch made up in FV in the same way one would normally use dry yeast Yep

 

Other option:

 

- Make 2-3L batch, and only use around 800mL (give or take) to ferment in the FV I think you have this the wrong way around - the extra 800mL is for harvesting into a mason jar for future, the remaining 1.5/2L or whatever in the flask goes into the FV.

- 'Feed' the batch back up to the 3L mark with 100g LDME : 1000mL water wort (boiled and cooled to same temp as batch prior to adding) This step is unnecessary because the starter has been built oversize to begin with. e.g. if the calculator recommends a 2 litre starter for a batch of wort, you'd build it to 2.8 litres, then when you harvest the 800mL into the jar, you're left with the original 2 litres to go into the FV.

- Store remaining starter at room temp, covered

^^^ Or should the flask be refrigerated? I always refrigerate my flask for a day or two before pitching, to enable me to decant off most of the spent beer, leaving just enough to swirl up the yeast cake. I also take it out of the fridge on pitching day to let it warm up prior to this.

 

 

 

The process for harvesting yeast prior to bottling is:

 

- Swirling the bottom 4-500ml around

- Let it settle for a few minutes

- Decant 300ml or so using the tap into a sterile 500ml flask

- Cover with foil

- Refrigerate for up to one month

- Replenish with fresh wort made up at a ratio 100g LDME : 1000mL water each month if not repitching the yeast into a new batch of beer (to do this, ensure the yeast has mostly settled to the bottom, and tip off most of the solution before topping back up)

 

You can do this, but personally I prefer harvesting from the yeast starter, because the yeast is subjected to the exact same 1037 SG unhopped wort every time I make one. This differs from actual beers that vary in OG/ABV and hopping levels, meaning the yeast are subjected to different conditions and each harvest will probably differ in health and vitality. The yeast is also cleaner than what comes out of the trub in the FV, which I prefer.

 

Cheers,

Aaron.

 

 

[Otto Von Blotto]

I have my first yeast starter to go from Coopers Pale Ale yeast. It finished fermenting on Monday so its been in the fridge for the last few days.

When my brew is ready can I just shake it up and put into the brew once its back to room temperature?

Or do I need too add more LDM and boiled water once cooled to it' date=' to get fermenting again?

Also above 18 its meant to get banana flavours. As this fermented in my pantry Im sure it has a banana smell/flavour. Since its cold crashed should I pour off the top half of the liquid or will I risk loosing to much of the yeast?[/quote']

 

What size starter did you use and how much yeast? Without this info it's impossible to say whether it needs to be stepped up with more wort.

 

You can most certainly pour off most of the spent beer if it has been cold crashed. This is a regular part of my routine so as to eliminate diluting the main batch with unhopped beer fermented at whatever the room temp was when I did the starter.

[Shibby]

I originally had the bottom of 10-12 stubbies, which were combined into 2 stubbies in the fridge. They were in there for a few weeks before using. I poured of most of the liquid as the cloudy stuff was all at the bottom, oh and added the bottom of a vintage ale i was drinking while doing the work.

I mixed in 600ml water and 60grams LDM like the coopers list on here says. I then split it and added another mix of 600ml, and 60g LDM, so i have 2 600ml solutions. Both also had yeast nutrients.

Both fermented nicely. I split after the first lot fermented.

[Otto Von Blotto]

Ok, are you planning to pitch one or both of the 600mL solutions into the FV? If both, then you can simply decant the spent beer, swirl them up and pitch them. If one, then you may be better off making up a 100g/1L solution and re fermenting in that, or there may be enough yeast already in one of them. Without knowing an approx. cell count it's hard to advise one way or the other really.

[Shibby]

Thanks for your advice, I was planning on saving the second for another brew, if i pull this AG clone off and it works Ill be happy to have this as a regular session brew.

I may pour some off and and add some more like you mentioned, I may let it ferment at 16-18 then just tip it all in.

[Otto Von Blotto]

Fair enough. Yep if you add more and ferment it again, you can simply pitch it while active, and it should take off pretty well in the FV!

[Austy]

Thanks for your help Otto :-)

 

I'm hoping to have a go at this on Wednesday.

 

Cheers,

Aaron.

[Otto Von Blotto]

No worries Austy

 

I'm no expert on yeast, but I have developed and fine tuned my process over the last 6-7 months and it does work well for me, and I think it would work well for others as well. I like to keep things as simple as possible without sacrificing on other areas like sanitation or quality and the starter process I use achieves that. I know my numbers aren't exact, but the beers always turn out excellently so I guess I must be doing something right.

 

Let us know how you get on with it!

 

Cheers

 

Kelsey

[Graculus]

For those using stir plates' date=' any idea what rpm they run at? I'm looking at computer fans and about the slowest I've seen is 2,500 RPM while many others are up around 5,000. Is that a big deal?[/quote']

 

I haven't made mine yet but I was going with a computer fan with magnet attached.

I've bought a speed controller for the fan so I can adjust the speed if needed.

http://www.ebay.com.au/itm/Computer-CPU-3-Pin-Fan-Cooler-Speed-Controller-12V-DC/220951783233?_trksid=p3693.c100102.m2452&_trkparms=ao%3D1%26asc%3D20140212121249%26meid%3D814b34e81e5d4aa9811f82c24dabd2b3%26pid%3D100102%26

[Austy]

I put on a starter yesterday. 2.5L boiled and cooled water, 250g of LDME and 11.5g hydrated US-05. I had a look at the calculator and was somewhat confused - but I figure that any starter is better than dry pitching.

 

Just wondering - why use LDME to feed the yeast, as opposed to a cheaper sugar such as dex? Particularly if the spent wort is to be binned after cold crashing the starter?

 

Cheers,

 

Aaron.

[Beerlust]

Hi Austy.

Just wondering - why use LDME to feed the yeast' date=' as opposed to a cheaper sugar such as dex? Particularly if the spent wort is to be binned after cold crashing the starter?

[/quote']

Malt has additional nutrients as part of its composition that aid in yeast growth & overall health. Dextrose is a simple sugar & although yeast will consume it, it does hinder the newly produced yeast cells ability to successfully digest/ferment more complex malt derived sugars as it becomes exposed to them (in a full wort) by continually re-using a dextrose based starter.

 

BTW, you don't have to bin the starter wort provided the malt used in it does not interfere with certain other malts used in your main recipe wort, or that the starter volume is not of an excessively high volume where typical esters produced in an uncontrolled temp starter can present.

 

Cheers,

 

Lusty.

[Austy]

Awesome - good to know. Thanks Lusty!

 

That brings one more question (as responses typically do!) - Is there any negative effect in using the starter wort to make up a 23L batch due to the level of air exposure it has incurred?

 

And one more... It's been 24 hours since pitching, but I haven't seen any activity... Except for pressure formed in the flask (foil cap was slightly ballooned), and hissing noise when swirling to oxygenate.

 

Thanks again,

 

Aaron.

[Beerlust]

That brings one more question (as responses typically do!) - Is there any negative effect in using the starter wort to make up a 23L batch due to the level of air exposure it has incurred?

I'm not quite following you here on this one' date=' so please excuse anything unhelpful in my response. [img']innocent[/img]

 

Yeast starters are usually covered with foil, or glad wrap just like the top of your fermenter would be to minimize the risk of outside influences spoiling your ferment.

 

The whole concept behind making a starter is with the intention of eventually pitching that into you full brew wort. For us home-brewers that is usually something around the 23 litre mark.

 

The point of a starter is to give the yeast a smaller volume of wort that it can quickly & easily control, & to increase its cell count numbers putting them in an active state whereby they are less likely to allow foreign "wild" yeasts to introduce themselves & interfere with the full volume ferment.

 

I hope that helps answer your question.

 

Lusty.