Using a magnetic stirrer for yeast starters

[iBooz2]

I have aimed this topic at @Classic Brewing Co but others may get some useful knowledge out of it.  Also @Shamus O'Sean is going to add some photos as well so hopefully it will become a bit of a tutorial for others wanting to harvest and propagate their favorite yeasts.

Getting to know your magnetic stir device.

You will probably need both a 3 L and a 5 L Erlenmeyer flask so I would get those ordered ASAP and say 2 spare stir bars.  Your 1 L flask will still come in handy.  Practice with water in your flask first so you can see what’s going on.  With your 1 L Erlenmeyer flask fill it up level to the 600ml mark and put in the stir bar.  Have the stir plate power off and speed control knob set at the very minimum position.

Getting the stir bar central in the flask is the first tricky bit.  I hold the flask up and use another magnet such as a fridge magnet or a spare stir bar to position the internal stir bar into the centre of the flask. It may be hard to see with wort looking though from the side so that why holding it up and centralising the bar works better.

Lower the flask vertically and centrally onto the magnetic stirrer without moving the stir bar.  Have a very fine pointed texta handy.

Turn the power on to the magnetic stirrer and then very slowly turn the speed dial up until you get to a point where there is a nice little vortex in the middle of the water.  If you go too fast you risk spinning the sir bar off to the side and its game over. 

Once you have what I call a ‘comfortable and stable vortex’ going, using your texta put “1” dot adjacent to the mark on the speed control knob.  This will be your reference position for your 1 L Erlenmeyer flask.

When you get a 3 L Erlenmeyer flask do the same thing but just fill it to the 2 L mark and obviously it will take more rotational energy to spin that volume up to a comfortable and stable vortex.  Now put 3 dots adjacent to the mark on the speed control knob.  Put the 3 dots in a straight line radiating away from the control knob.  This will now be your reference point for a 3 L flask.

Do the same for a 5 L flask with 3 L of water but this time put a small “V” adjacent to the mark on the speed control knob to represent your 5 L flask.

Once you have these marks it’s easy just to drop the flask onto the plate vertically and then dial the speed required for that size flask with very little minor adjustment.

You do not fill any flask all the way up.  You want to maximize the surface area of wort to air and make it easy to calculate volumes from brewing software and web site starter calculators etc.  That’s why I pretty much always do 2 L of starter in a 3 L flask and 3 L of starter in a 5 L flask.  Plus you have to leave room for the Krausen.

Sanitizing the flask, wort and stir bar is the next tricky bit.

I prefer to mix up the required volume of water and light dry malt in the flask itself drop in the stir bar then place it on a heat source.  I use and OG of 1.035 for the first step of my starters.

If using gas I recommend using a diffuse to help distribute the heat evenly into the Erlenmeyer flask to prevent hot spots.  I use both a trivet (which gives the flask great stability on the cook-top) and one of those SS camping toaster replacement gauze's to further diffuse the heat.

Do not use foil over the top at this stage, leave top of flask open.

As the wort heats up give the flask a bit of a swirl around.  Eventually the flask will get too hot to handle so now you have to leave it and watch very carefully because given the closed in chimney effect of the throat of the flask it will boil over very easily and make a big mess.  When the sticky bubbles (hot break) start to foam it creates a virtual lid on the wort which traps in the steam and it will then suddenly boil a lot quicker that you expect creating a volcano effect.  I normally turn my heat off well before the boil then back on low every now and then to sneak up on the simmer.

Warning: even if you turned the heat source off just prior or on boil to try and stop the volcano the stored heat in the flask will bring you unstuck and turn your stove-top into a very sticky mess.  You will have to get to know your particular heat source.

Once a stable boil is underway, say just bubbles coming off the stir bar, I get a 300 mm square of foil and spray it both sides with sanitiser then fold it into 4 to give me a thick layer of foil.  Place this over the top of the flask, crimp down but don’t seal as you want some steam to come out and sanitise the outside top of the flask and the foil.  Watch the heat level here to prevent a boil over.  After a few minutes turn off the heat and crimp the foil down tight all around the flask rim.

Cooling the flask down:

I usually allow it to cool down by itself to a point where I can safely handle the flask and take it to a sink of cooler water and sit it in there for a while, changing / refreshing to colder water often as the heat is transferred.  Once it’s cool enough I then put the flask in the fridge to bring it down to required pitching temps.

Edited December 29, 2022 by iBooz2

[Classic Brewing Co]

15 minutes ago, iBooz2 said:

I have aimed this topic at @Classic Brewing Co but others may get some useful knowledge out of it.  Also @Shamus O'Sean is going to add some photos as well so hopefully it will become a bit of a tutorial for others wanting to harvest and propagate their favorite yeasts.

Getting to know your magnetic stir device.

You will probably need both a 3 L and a 5 L Erlenmeyer flask so I would get those ordered ASAP and say 2 spare stir bars.  Your 1 L flask will still come in handy.  Practice with water in your flask first so you can see what’s going on.  With your 1 L Erlenmeyer flask fill it up level to the 600ml mark and put in the stir bar.  Have the stir plate power off and speed control knob set at the very minimum position.

Getting the stir bar central in the flask is the first tricky bit.  I hold the flask up and use another magnet such as a fridge magnet or a spare stir bar to position the internal stir bar into the centre of the flask. It may be hard to see with wort looking though from the side so that why holding it up and centralising the bar works better.

Lower the flask vertically and centrally onto the magnetic stirrer without moving the stir bar.  Have a very fine pointed texta handy.

Turn the power on to the magnetic stirrer and then very slowly turn the speed dial up until you get to a point where there is a nice little vortex in the middle of the water.  If you go too fast you risk spinning the sir bar off to the side and its game over. 

Once you have what I call a ‘comfortable and stable vortex’ going, using your texta put “1” dot adjacent to the mark on the speed control knob.  This will be your reference position for your 1 L Erlenmeyer flask.

When you get a 3 L Erlenmeyer flask do the same thing but just fill it to the 2 L mark and obviously it will take more rotational energy to spin that volume up to a comfortable and stable vortex.  Now put 3 dots adjacent to the mark on the speed control knob.  Put the 3 dots in a straight line radiating away from the control knob.  This will now be your reference point for a 3 L flask.

Do the same for a 5 L flask with 3 L of water but this time put a small “V” adjacent to the mark on the speed control knob to represent your 5 L flask.

Once you have these marks it’s easy just to drop the flask onto the plate vertically and then dial the speed required for that size flask with very little minor adjustment.

You do not fill any flask all the way up.  You want to maximize the surface area of wort to air and make it easy to calculate volumes from brewing software and web site starter calculators etc.  That’s why I pretty much always do 2 L of starter in a 3 L flask and 3 L of starter in a 5 L flask.  Plus you have to leave room for the Krausen.

Sanitizing the flask, wort and stir bar is the next tricky bit.

I prefer to mix up the required volume of water and light dry malt in the flask itself drop in the stir bar then place it on a heat source.  I use and OG of 1.035 for the first step of my starters.

If using gas I recommend using a diffuse to help distribute the heat evenly into the Erlenmeyer flask to prevent hot spots.  I use both a trivet (which gives the flask great stability on the cook-top) and one of those SS camping toaster replacement gauze's to further diffuse the heat.

Do not use foil over the top at this stage, leave top of flask open.

As the wort heats up give the flask a bit of a swirl around.  Eventually the flask will get too hot to handle so now you have to leave it and watch very carefully because given the closed in chimney effect of the throat of the flask it will boil over very easily and make a big mess.  When the sticky bubbles (hot break) start to foam it creates a virtual lid on the wort which traps in the steam and it will then suddenly boil a lot quicker that you expect creating a volcano effect.  I normally turn my heat off well before the boil then back on low every now and then to sneak up on the simmer.

Warning: even if you turned the heat source off just prior or on boil to try and stop the volcano the stored heat in the flask will bring you unstuck and turn your stove-top into a very sticky mess.  You will have to get to know your particular heat source.

Once a stable boil is underway, say just bubbles coming off the stir bar, I get a 300 mm square of foil and spray it both sides with sanitiser then fold it into 4 to give me a thick layer of foil.  Place this over the top of the flask, crimp down but don’t seal as you want some steam to come out and sanitise the outside top of the flask and the foil.  Watch the heat level here to prevent a boil over.  After a few minutes turn off the heat and crimp the foil down tight all around the flask rim.

Cooling the flask down:

I usually allow it to cool down by itself to a point where I can safely handle the flask and take it to a sink of cooler water and sit it in there for a while, changing / refreshing to colder water often as the heat is transferred.  Once it’s cool enough I then put the flask in the fridge to bring it down to required pitching temps.

Thanks heaps Al, I will study it. Cheers.

[Marty_G]

Another point is you can overbuild starters and harvest from the starter then use that to build your next and repeat. The beauty of this is you then using fresh liquid yeast constantly.   Attached is my little yeast bank of WLP090, WLP001, M54, Nottingham and WLP002.  They are my go too yeasts and each one is from a fresh starter.  Just pour off most the liquid, swirl to suspend all the yeast then pour into the starter mix.  I usually harvest about 400ml.  Saves some cash but more importantly you use the correct amount of yeast and it is fresh and already fermenting.   On most occasions I can see active wort fermentation in about 5 -6 hours.  

Edited December 30, 2022 by Marty_G

[RDT2]

3 hours ago, Marty_G said:

Another point is you can overbuild starters and harvest from the starter then use that to build your next and repeat. The beauty of this is you then using fresh liquid yeast constantly.   Attached is my little yeast bank of WLP090, WLP001, M54, Nottingham and WLP002.  They are my go too yeasts and each one is from a fresh starter.  Just pour off most the liquid, swirl to suspend all the yeast then pour into the starter mix.  I usually harvest about 400ml.  Saves some cash but more importantly you use the correct amount of yeast and it is fresh and already fermenting.   On most occasions I can see active wort fermentation in about 5 -6 hours.  

I’ve started doing that as well!

Makes liquid yeasts affordable IMO.

I also definitely recommend getting two stir bars as well. They go missing and also if you aren’t careful you tip them in the fermenter!

[Classic Brewing Co]

3 hours ago, Classic Brewing Co said:

Thanks heaps Al, I will study it. Cheers.

Al printed out & also in PDF format so I can work this bad boy out.

Cheers.

[iBooz2]

The gas cook-top heat diffuser I use is made up of two parts, a trivet and inside that a fine woven toaster mesh.  Not needed on an electric cook-top IMO.

The SS camping trivet part is available from BCF.

The fine SS mesh is available from Anaconda.

[RDT2]

Coastal Haze yeast starter underway in preparation for a Jedi Juice clone in the next few days! I have far too many hops in the freezer so thought I would give that one a crack off Brewfather. 

[Otto Von Blotto]

There is a type of dry malt that doesn't boil over like crazy in these flasks. I'm not sure how to describe it other than it's more coarse than something like the Cooper's one is. It also dissolves a hell of a lot easier without the clumping of the other one. It's pretty much all mixed in before it even boils so I can just put the flask on and wait. I always try to get this type for starters for this reason, I did have issues with boilovers with the other stuff. 

Also, smooth stir bars are ideal, as opposed to the ones with a ring around the centre. The latter type are quite noisy by comparison. I find them easy enough to centre in the flask by holding it on a slight angle over the stir plate so the bar is at the edge of the flask, the magnet can then grab it and I can move the flask into position. 

Edited December 31, 2022 by Otto Von Blotto

[Marty_G]

3 hours ago, Otto Von Blotto said:

There is a type of dry malt that doesn't boil over like crazy in these flasks. I'm not sure how to describe it other than it's more coarse than something like the Cooper's one is. It also dissolves a hell of a lot easier without the clumping of the other one. It's pretty much all mixed in before it even boils so I can just put the flask on and wait. I always try to get this type for starters for this reason, I did have issues with boilovers with the other stuff. 

Also, smooth stir bars are ideal, as opposed to the ones with a ring around the centre. The latter type are quite noisy by comparison. I find them easy enough to centre in the flask by holding it on a slight angle over the stir plate so the bar is at the edge of the flask, the magnet can then grab it and I can move the flask into position. 

Pretty sure it is MJ's LDM. I use the same method to centre the stir bar, easy as. 

[Otto Von Blotto]

4 hours ago, Marty_G said:

Pretty sure it is MJ's LDM. I use the same method to centre the stir bar, easy as. 

It could be. I just get it from craftbrewer or the local country brewer or whatever they're called. Doesn't have a brand name on it but it works. 

[kmar92]

8 hours ago, Otto Von Blotto said:

There is a type of dry malt that doesn't boil over like crazy in these flasks. I'm not sure how to describe it other than it's more coarse than something like the Cooper's one is. It also dissolves a hell of a lot easier without the clumping of the other one. It's pretty much all mixed in before it even boils so I can just put the flask on and wait.

I think that the dry malt that you refer to is band dried whereas the Coopers dry malt is spray dried and the difference in the drying process causes the different textures.

The spray dried version is crazy hard to dissolve in a uniform manner as it clumps up as soon as it hits a liquid, whilst the band dried is much better to dissolve without clumping.

[Otto Von Blotto]

That makes sense. It's a curiosity why one foams up like a mofo upon boiling whereas the other is far less volcanic. It still develops a foamy layer on top but it quickly turns into larger bubbles that disintegrate before any of it has a chance to spill out the top. The other thing I noticed with the spray dried type was these large pieces of grey matter (not brains ) floating around in the wort when it boiled, which doesn't occur with the other one. 

In any case it was a pita to work with for this purpose, so I would recommend the coarser band dried malt for it. 

 

Edited December 31, 2022 by Otto Von Blotto

[iBooz2]

HARVESTING CCA YEAST.

About 3 weeks before I plan to pitch some harvested CCA yeast into a brew I buy a fresh six-pack of Coopers Pale Ale.  I check the Best After date on the pack and buy the freshest ones available in the grog shop.  Remember Coopers use a Best After Date not a best before dates so get some that are as young as possible per this date (see pic as an example).

I only buy stubbies that are stored standing up right and when I take them to the cashier I hold the pack up high so he/she can scan the bar code on the bottom of the pack.  Otherwise the cashier will tip the pack over on its side and scan and this disturbs the yeast somewhat.  Store the six-pack in your fridge upright for about a week to ensure maximum settling of the yeast in the stubbies.

A day before I am going pitch the harvested yeast into my starter, I make sure I have boiled the required L volume (amount of malt and water) in my Erlenmeyer flask and it has cooled to pitching temps.  Obviously it is covered tightly with some foil.

Next I take the six-pack of stubbies and remove from the cardboard and stand all of them up in a Tupperware dish or something similar.  I spray the stubbies all over with sanitiser making sure to spray up under the crimp ripples of the caps thoroughly.  Place the dish and stubbies back into the fridge so the dish can collect excess sanitiser. Place a rubber band on one of the stubbies as this will be my mother bottle. Let the sanitiser work for about 30 minutes.  Yes I know only 3 stubbie in pic for - demo.  Also its an old photo as Best After Sept 2022.

Decant each stubbie starting with the mother bottle.  I use a piece of paper towel soaked in sanitiser to unscrew the lid, carefully pour the beer into a glass leaving about 20 mm of beer and of course the yeast in the bottom of the stubbie.  Respray the stubbie top lip and lid with sanitiser and then re-screw the original lid back on temporarily.

As I decant the next stubbie to a glass leaving the same 20 mm, I give it a bit of a swirl and then pour the trub into the mother bottle, re-sanitising the top lip and lid on the mother bottle as I go.  Discard the donor bottle and lid to recycling.

Continue during the course of the session until all stubbie trub’s have been transferred to the mother bottle which is stored in the fridge during the entire session.

I prefer to use a mother bottle rather than opening the starter flask as you empty each stubbie as that exposes it to wild yeasts each time.  By using a mother bottle method you will only open up your starter flask once and that is when you tip the mother into it.

Edited January 1, 2023 by iBooz2

[MitchBastard]

If I can add anything to this topic, it’s not so much about the stirrers or flasks (I’m a 5litre plastic bottle shake the bugger guy) but using yeast nutrient, anti foam and also adjusting the starter pH to somewhere between 5.6-5.8 will help with general starter health and vitality and viability.
 

Edited January 1, 2023 by MitchBastard

[iBooz2]

9 hours ago, MitchBastard said:

If I can add anything to this topic, it’s not so much about the stirrers or flasks (I’m a 5litre plastic bottle shake the bugger guy) but using yeast nutrient, anti foam and also adjusting the starter pH to somewhere between 5.6-5.8 will help with general starter health and vitality and viability.
 

Good points Mitch and thanks for bringing them up.  I did omit to mention putting in some nutrient during the starter boil so a good reminder to do that, It does a better job in the starter than in the brew wort.  I have the proper yeast nutrient but sometimes I just use a packet or two of old well out of date yeast.  Suggest @Classic Brewing Co could just use his old yeasts too just to start him off with and then down the track get some yeast nutrient powder.

I never thought about the starter pH.  Next time I make one will test it to see where it sits.  Thanks again Mitch.

Edited January 2, 2023 by iBooz2

[iBooz2]

On 12/31/2022 at 2:37 PM, Otto Von Blotto said:

I find them easy enough to centre in the flask by holding it on a slight angle over the stir plate so the bar is at the edge of the flask, the magnet can then grab it and I can move the flask into position. 

Thanks Otto, yes that trick is in the intermediate / advanced course  this is a beginners course for @Classic Brewing Co.

I use the fridge magnet to centre first as the little wine chiller I use as a starter temp controlled fridge is a big cramped for space to tilt over the 5 L flask plus I am down at floor level on my knees so want it on and centered as easy as I can.

[Classic Brewing Co]

1 hour ago, iBooz2 said:

Good points Mitch and thanks for bringing them up.  I did omit to mention putting in some nutrient during the starter boil so a good reminder to do that, It does a better job in the starter than in the brew wort.  I have the proper yeast nutrient but sometimes I just use a packet or two of old well out of date yeast.  Suggest @Classic Brewing Co could just use his old yeasts too just to start him off with and then down the track get some yeast nutrient powder.

I never thought about the starter pH.  Next time I make one will test it to see where it sits.  Thanks again Mitch.

Hi Al yes, I have plenty of yeast in the fridge, but I also have been using Yeast Nutrient for years. I look forward to this all happening.

[Otto Von Blotto]

17 hours ago, iBooz2 said:

Thanks Otto, yes that trick is in the intermediate / advanced course  this is a beginners course for @Classic Brewing Co.

I use the fridge magnet to centre first as the little wine chiller I use as a starter temp controlled fridge is a big cramped for space to tilt over the 5 L flask plus I am down at floor level on my knees so want it on and centered as easy as I can.

Ah, yeah fair enough lol. I just do mine on the kitchen bench. Never seen any point in temperature controlled starters but in saying that I do tip out most of the wort when I pitch them so any potential off flavours from growing the yeast at 30+ degrees is a non issue. 

[Shamus O'Sean]

MAKING A YEAST STARTER INCLUDING AN OVERBUILD FOR THE NEXT BREW.

PDF version for easy printing: 

Making a yeast starter including an overbuild for the next brew.pdf

Introduction

Classic Phil just got a stir plate for doing yeast starters.  So I thought I would do a bit of a repeat of a thread from a few years ago when Otto demonstrated his yeast starter method.  The process includes doing an overbuild.  That is where you make enough yeast cells for the beer you are going to brew plus extra yeast to harvest and save for making another starter for the next brew.

Most of the equipment you will need to make a yeast starter.  Dry Malt Extract, a 3 – 5 litre borosilicate glass flask, magnetic stir bar (small white thing in front of the flask), funnel, scales, spray sanitiser, spoon, pot, stir plate, aluminium foil.  You do not need a stir plate; instead you can give the flask a shake every time you walk past it for the first 24 hours.

Yeast calculators

The first thing is to figure out how much yeast you need for your brew and how many active yeast cells you are starting with.  Do not be put off by the big sounding numbers.  Use a yeast starter calculator to figure out the numbers including the overbuild.  Brewers Friend or BrewFather are two examples of software you can use. 

The calculators use the wort gravity, volume, target pitch rate, yeast type, number of packets or grams to figure out how much yeast is needed for your brew.

If doing a starter with dry yeast, I assume 18 billion cells per gram of yeast.  This assumption is fine as long as the yeast is still in date and has been stored in the fridge.  I usually rehydrate the dry yeast in 10 times its weight of 30°C boiled and cooled water.  This step gives the yeast the best chance for maximising the number of healthiest cells.  However, you can pitch it straight in from the packet.

Liquid yeast usually states how many yeast cells are in the packet when it is packaged.  Yeast deteriorates over time.  The yeast calculators use the manufacturing date to tell you how many cells are left after a certain time.

Yeast slurry from a previous ferment has about 1.5 billion cells per ml of slurry.  It dies off too, so call brewday plus 3 days the date of manufacturing and allow for loss of viability.

If you are using an overbuild from a previous starter, you would have begun with a known cell count and will know how many cells were in your overbuild when it was harvested.  Add 2 days to the date you did the starter and call that the date of manufacturing and allow for loss of viability.

In my case I use BrewFather.  In the example below, I had made an overbuild of 200 billion cells of US‑05 on 6 November.  I was doing the next starter (for my Kaiju Krush) on 25 December.  In the 46 days since making it, the overbuild had dropped to 68% viability, so it only had 135 billion viable cells left.  The brew I was doing this starter for was 30 litres of 1.045 OG wort.  The calculator said I need 266 billion cells of US‑05.  Plus I wanted to make another 200 cell overbuild (not sure why the screenshot below says 199 billion cells overbuild).  So to make the total 466 billion cells, I needed to make a 2.4 litre starter with 236 grams of Dry Malt Extract.  Once the starter has finished fermenting, I have to harvest 1.03 litres to save and leave 1.37 litres in the flask for the Kaiju Krush.

The first day - Starting the starter (about 45 mins prep time and 45 minutes cooling time)

Now you can weigh out the DME and add the water, pour it into the flask and boil the starter wort in the flask.  I do that if the starter is less than half of the volume of the flask.  As others have pointed out, the issue is possible boil-over in the flask.  Some DME is more prone to boil-over than others.  To play it safe, as the starter in this case is close to half the capacity of my 5 litre flask, I am going to boil the starter wort in a pot then add it to the flask.

The flask still needs to be sanitised/sterilised.  Therefore, firstly drop your stir bar in the flask, pour about 1 litre of hot water into the flask and pop the funnel in the flask for a boil to sterilise.  We will use the funnel later.

You might note that I do not use anything to diffuse the heat from the gas burner.  Maybe not best practice, but all of my flasks (2 x 3 litre + 1 x 5 litre) have not had an issue.

 

Next weigh out the DME.  Then pour in the volume of hot water.  Use the scales to measure the correct amount of water.

   

 

It does not matter if your measuring is not 100% accurate.  Stir in any DME that has not dissolved.

   

 

Pop the starter wort on the stove to boil.

 

Now is a good time to get out your previous overbuild that was stored in the fridge.

 

I use alcohol swabs to sterilise the rim of the jar.  So go ahead and swab the rim.  Then let it dry for a minute or two.

   

 

Decant off most of the beer above the yeast.  Leaving mostly yeast in the bottom of the jar.  I suggest covering the jar with its lid or a piece of aluminium foil, sprayed with sanitiser.

   

 

By now, your flask of water should be boiling.  You will see that I have also inverted the funnel over the mouth of the flask to steam sterilise the inside of the flask.  You want to expose the funnel inside and outside to a few minutes of steam.  Once the funnel is sterilised, set it aside.  Grab the square of aluminium foil and wrap it around the mouth of the funnel using oven gloves.

   

 

The foil only has to be loosely wrapped around the mouth of the flask.  Set a timer for 3 minutes.  The escaping steam will sterilise the inside of the foil.

   

 

By now the starter wort will be boiling.  Set a timer for 5 minutes.  Give the boiling wort an occasional stir.

   

 

Once the 3 minute timer is up, remove the flask from the heat using baking gloves because the flask will be boiling hot.  Carefully remove the foil “lid” and set it aside.  Empty out the boiling water, being careful to not let the stir bar side out of the flask.

   

 

By now, the 5 minute timer for the starter wort boil should be finished.  Stand the flask.  Fit the funnel.  Remove the starter wort from the heat and carefully pour into the flask.  Remove the funnel and refit the foil “lid”.

   

 

Using gloves, pop the flask into a warm water bath.  These flasks are meant to be able to withstand boiling to freezing temperature changes, but I do not take the risk.  Rather than a small sink for your “bath” you can use any pot or vessel that will withstand the heat of the flask.

 

I leave the flask in the warm water for about 8 minutes.  Give the flask a swirl every now and again to help with the heat transfer.

 

Then I dump the now hot water and fill up the “bath” with cold water.  Leave it for another 8 minutes or so.  Repeat this process 4 -5 times or until the starter wort is 20 – 25°C.

 

Give the yeast in the jar a good swirl around to make it creamy.  Use another alcohol swab to sterilise the rim of the flask.

   

 

And the yeast jar.  And clean and sanitise the funnel from before.

   

 

Decant some of the starter wort from the flask into the yeast jar.  Wipe up any drops with the alcohol swab.  This will help to stir up the yeast and make it pour easier.

   

 

Once nice and runny, use the funnel to pour the yeast into the flask.  Wipe up any drips with an alcohol swab.

   

 

To make sure I get as much of the yeast out of the jar as possible, I pour some more of the starter wort back into the jar a second time.  Give it a swirl and pour back into the flask.

 

Now put the foil “lid” back on the flask.  Slightly tilt the flask so the magnetic stir bar is at the underside outer edge of the flask.  Slide the flask onto the stir plate so the position where the stir bar was passes across the middle of the stir plate.  The magnets under the stir plate should attract the stir bar and move it to the centre of the flask as you continue to slide the flask across the stir plate.  Make sure that flask is sitting centrally on the stir plate.

Turn on the stir plate and adjust the speed so that a vortex is created in the middle of the wort.  But not so fast that the stir bar spins off to the side of the flask

 

The photo above was just so you can see the vortex a bit better.  I actually put the stir plate and flask into a cardboard box in the lounge room where the temperature stays pretty constant.

 

Temperature of the starter is not so critical because you are not worried so much about off flavours. You are just growing more yeast.  Having said that, in the middle of winter, I will put a heat belt in the box (hence the porcelain tiles in the box).  Set it on 18°C so the wort does not cool down too much.  I never worry about keeping the starter cool.  However, the lounge never gets above 25°C anyway.

Leave the starter on the stir plate for 12 hours.  Some leave it longer, like 24 hours.  However, I read/heard somewhere that much more than 13-14 hours does something to the yeasties like stretching their molecules and affecting their fermenting performance.

The fourth day – Harvesting and storing the overbuild and retaining the yeast for brew day (about 45 mins prep time)

After 12 hours turn off the stir plate and leave the yeast to ferment out over the next 36 – 48 hours.  By that time it will look something like this.  You can see how the Krausen rose up the flask.  Do this in a 3 litre flask and you would have a Krausen volcano.

 

You can also see the layer of new yeast at the bottom.

 

Give the flask a swirl to knock most of the Krausen back into the liquid.  I also use another stir bar on the outside of the glass, to lift the stir bar inside the flask and swirl it around on the inside wall of the flask to clean the Krausen back into the liquid.

 

Once all the Krausen is cleaned off, get the stir bar back into the middle of the flask and turn the stir plate back on.  I leave it for 30 minutes or so.  By that time the yeast has completely mixed evenly into the liquid.

 

While the yeast is being mixed up, sterilise a jar, lid and tongs for storing the overbuild volume.  I usually use enough water to 3/4 fill the jar on its side.  Once at a boil, I leave it for 3 - 5 minutes.  Then I use the tongs to turn the jar over and boil it for another 3 – 5 minutes.  The overbuild from this starter will be stored in this Mason jar.

 

Remove the jar and the lid with the tongs and store to cool down.  By the time the yeast is mixed up, the jar should have cooled to room temperature.  You want it less than 30°C.  If it is still a bit warm, I will sometimes run the outside of the glass under a cold tap, being careful to not get any water inside the jar.  Do not do this with a jar freshly out of the boiling water.  Cheap Mason jar glass is too fragile and will break if switched from hot to cold too quickly.

 

Once the yeast is well mixed, turn off the stir plate and remove the flask.  Take off the foil “lid”.  Use another alcohol swab to sterilise the mouth of the flask.

 

Use another stir bar, held on the outside of the flask, to carefully remove the stir bar from the flask by attracting it from the bottom of the flask and dragging it up the inside of the flask.  Using a finger, without touching the inside of the flask, I press on the stir bar and slide it out of the flask.

 

Swirl up the yeast in the flask again because, even in this short space of time, it will have started to settle on the bottom again.  You want it as evenly spread through the liquid as possible. Decant the desired volume of overbuild from the flask into the Mason jar.  I use kitchen scales, zeroed after the Mason jar is placed on them.  Assume 1 gram of liquid is 1 ml of liquid.

 

Gently turn the lid onto the Mason jar.  Do not tighten it up.  Leave it loose enough to allow any build-up of air to escape.  The concoction should not ferment anymore because it should be fermented out already.  Plus you are putting it in the fridge that will inhibit further fermentation too.  Put the Mason jar in the fridge.  This is the overbuild that will be used for our next starter.  I realised after putting this in the fridge that it was a US-05 yeast, but I had wrongly used a CCA (Coopers Commercial Ale) label.  Within a couple of days, the yeast will have settled to the bottom like the Czech Lager yeast in the Mason jar beside my US-05 yeast.

 

Put the foil “lid” back on the flask and put it in another fridge to allow the yeast to settle out to use in the upcoming brew.

 

[Classic Brewing Co]

Jeez Shamus that's longer than the Gettysburg address, Abraham Lincoln would be impressed. 

I must say that is the most comprehensive & thorough description I have seen, thank you heaps, I had no idea it was so complex.

It will take a while to absorb all of that so I will have to read it carefully, good idea with the PDF as that will certainly make it easier. 

Well done mate & thank you.

[Otto Von Blotto]

That's pretty much how I do it except for boiling the wort in the flask itself rather than a pot, and just leaving it there to cool on its own (covered of course), no chill if you will. I leave the stir bar in until it's pitched into the batch, occasionally I accidentally tip it in as well but I try to be careful pouring it to not have this happen. 

[Shamus O'Sean]

8 hours ago, Classic Brewing Co said:

Jeez Shamus that's longer than the Gettysburg address, Abraham Lincoln would be impressed. 

I must say that is the most comprehensive & thorough description I have seen, thank you heaps, I had no idea it was so complex.

It will take a while to absorb all of that so I will have to read it carefully, good idea with the PDF as that will certainly make it easier. 

Well done mate & thank you.

Thanks, Phil.  I just happened to be making this starter a few days after you got the stir plate from Boozer.  So I thought I would take a bunch of photos of the process.  I did not think at the time that putting the story together would take so long or that the post would turn out to be so long.

The actual starter is easier to do than some of the meals you prepare.  I have no doubt that you can do it.

I took a photo of almost everything (and probably more than necessary).  However, the process is pretty simple:

• Boil the starter wort
• Cool the starter wort
• Add the yeast
• Pop it on the stir plate
• Leave for a few days to do its thing
• Harvest and split the starter into overbuild and remaining starter
• Pop into fridge until ready to use

[Shamus O'Sean]

5 hours ago, Otto Von Blotto said:

That's pretty much how I do it except for boiling the wort in the flask itself rather than a pot, and just leaving it there to cool on its own (covered of course), no chill if you will. I leave the stir bar in until it's pitched into the batch, occasionally I accidentally tip it in as well but I try to be careful pouring it to not have this happen. 

It is not surprising because I began doing my starters by following your excellent post from four years ago.  I still have it book-marked.

 

I'll sometimes boil the wort in the flask too.  The DME I currently have is the finer stuff.  The two starters before this one both came close to boil overs.  So, I decided to do the "in pot boil" instead.

If I was more organised, I would do the boil earlier, so I could just let the starter wort cool "no chill" style too.

[Classic Brewing Co]

4 minutes ago, Shamus O'Sean said:

Thanks, Phil.  I just happened to be making this starter a few days after you got the stir plate from Boozer.  So I thought I would take a bunch of photos of the process.  I did not think at the time that putting the story together would take so long or that the post would turn out to be so long.

The actual starter is easier to do than some of the meals you prepare.  I have no doubt that you can do it.

I took a photo of almost everything (and probably more than necessary).  However, the process is pretty simple:

• Boil the starter wort
• Cool the starter wort
• Add the yeast
• Pop it on the stir plate
• Leave for a few days to do its thing
• Harvest and split the starter into overbuild and remaining starter
• Pop into fridge until ready to use

Cheers Shamus, I am sure your tutorial will help others too, so you have done well, I for one will save it & the PDF & try to get it sorted.

All I was doing before as gathering a quantity from the bottom of the FV, whack it in an Erlenmeyer Flask covered, whack it in the fridge up to about 2 weeks.

I got away with it a few times, but I was never sure about the quantity, last time I used about 600ml which appeared to be too much.

I realise now that it is a very different process.

Cheers.

[MitchBastard]

On 1/2/2023 at 5:11 PM, iBooz2 said:

Good points Mitch and thanks for bringing them up.  I did omit to mention putting in some nutrient during the starter boil so a good reminder to do that, It does a better job in the starter than in the brew wort.  I have the proper yeast nutrient but sometimes I just use a packet or two of old well out of date yeast.  Suggest @Classic Brewing Co could just use his old yeasts too just to start him off with and then down the track get some yeast nutrient powder.

I never thought about the starter pH.  Next time I make one will test it to see where it sits.  Thanks again Mitch.

No wuz. I don’t always adjust the pH at home. Unless it’s liquid yeast and it’s getting close to its BB date. It’s something we certainly do on the commercial side, particularly when liquid yeast can cost $500. You want to give it the best invoronment possible. 
 

This may be my imagination but I’ve noticed something that relates to your comment about yeast nutrient and the boil. Powdered yeast nutrient fires up the starter quite well, nothing noticeable for wort as you say, BUT I’ve found that if I use old harvested yeast from a clean lager, in the boil, the wort fires up incredibly fast. Probably plenty of differing factors here but just certainly something that’s been noticeable many times.