1. Yeast Starter growing and using yeast
Chris Taylor Melbourne Brewers
Mar 2009

2. Yeast Starters
Why?
What?
Process
Dry yeast

3. Why?

4. Why? Healthy yeast = happy beer :)‏
If you get the first step wrong you are setting yourselves up for failure before you even start.
Benefits
most probably save money
you will have fresh viable yeast
you will learn about yeast behaviour before pitching it

5. Why?
Increasing yeast cell count for:
Higher gravity beers
Larger batches
Under pitching consequences
Long time for fermentation to start (lag time)‏
Greater risk of infection
Formation of more yeast defects (esters etc)‏
risk of incomplete fermentation
In short you may get away with it for some of the more robust yeast strains, but results are much less predictable.

6. Why? Ensuring yeast is healthy before pitching
Old yeast with low viability
'Cheap' out of date liquid yeast packets
Saved yeast slurries left for too long (> 3 weeks)‏

7. Why not? Alternatives More time More complex Greater risk of infection
But is usually detectable
Alternatives
Buy more yeast
Re using yeast

8. What?

9. What Growing yeast, not making beer!
Need to provide ideal growth conditions
Not the same as for ideal beer production
Same for lager and ale yeasts
Wort ~ to 1.040
Temp ~ 26C
Constant agitation
Driving off CO2 helps yeast production
Nutrients (especially oxygen)‏

10. Yeast phases Lag Phase Wort acclimatization
Oxygen is extremely important.
used by yeast for synthesis of sterols and fatty acids necessary for growth factors.
Without oxygen growth will be very limited.
Log Phase
The log phase is a time of exponential growth of the yeast culture.
The preparation the yeast made during the lag phase allows rapid multiplication of cells and consumption of sugar.
Many of the significant aromatic and flavor compounds are by- products of cell growth and are produced during the log phase.

11. Yeast phases Stationary Phase
Where the yeast population reaches maximum density and the remaining sugars are consumed.
When the yeast have consumed all of the sugar, flocculation begins.

12. Process

13. Equipment Vessel to grow yeast in Must be sanitised of course!
Plastic container (eg Juice bottle)‏
Jar
Emerlyser flask
Can sanitise with heat (heat on stove)‏
Easy to use with a stirplate
No need for airlock
Makes yeast work harder.
Reduced oxygen has big impact on yeast growth.
Foil over the top is fine while CO2 is being produced.
Not suitable after CO2 production has ceased.

14. Equipment Stirplate Really need emerlyser flask
Can greatly accelerate yeast growth
Drives off CO2
Keeps yeast in suspension
Allows more air/yeast contact, potentially allowing more oxygen access.
You need one if you use start from small amounts of yeast
Slants or plates, culturing from bottle dregs, etc

15. Ingredients – Starter Wort
Dry malt extract
1gm per 10 ml for ~ SG
Should be boiled up to ensure it is sanitised
Liquid malt extract
Can get at HBS and sometimes low quality types at supermarket
Saved wort
Must be sterile to store at room temp
Can be frozen, but needs to sanitised after defrosting

16. Ingredients – Starter Wort
Sugar?
Not recommend, does not contain any FAN or other required nutrients
May be used with nutrients but still better to go with malt.
No hops (or as low as possible)‏
Reduces yeast growth

17. Ingredients - Yeast Packaged liquid yeast
Yeast from a commercial bottle
Not really necessary these days with Wyeast and Whitelabs range, exception being Coopers.
Slant or some other stored yeast
Dry yeast?
Generally not worth it, and yeast is designed to be pitched as is (does not even require much aeration)
Only real difference is the amount of yeast you start with. The more yeast the better!

18. Ingredients - Yeast Quality of starting yeast is important
Bad parents will result in more likelihood of demented children.
There are ways to reculture suspect yeast, but that is a whole new topic.
Try to avoid “stressed” and over-used yeast.
Each propagation risks more mutations
Yeast used in high gravity brewing is not recommended (its well and truly passed its best)‏

19. Ingredients - Yeast
Try to get yeast closest to the “source” of known good yeast in following preference:
Liquid yeast packet from yeast supplier
Slant or stored yeast from above
Yeast collected from Krausen
Yeast from secondary
Yeast from primary
Yeast from bottle
Yeast just found lying around the shed floor :p ( this is commonly known as an infection)‏

20. Ingredients - Others Yeast nutrient Oxygen!!! FAN (Nitrogen)
Generally available from the malt in the starter wort
Old yeast boiled up
I just use cheap bakers yeast
Specialised nutrient
Contains minerals such as Zinc and Magnesium, yeast hulls, diammonium phosphate etc
Will give the best overall results
Oxygen!!!
Is critical to yeast growth

21. Process – Estimating required yeast
How much yeast do I need?
Pitching rates
Experience!!! << This is the most important factor
Mr Malty pitching calculator
Generally accepted as 0.75 million cells per ml per º plato wort strength ( 1 plato ~ )
Need to double for lagers.
(just use the yeast calculator if you have access to it)‏
This is a guideline only, and is often disputed!!
You really need to be familiar with the yeast strain to know how to use it properly.
No substitute for experience

22. Process – Estimating required yeast
Ale yeast, OG and 23 litres
0.75mil x 23,000 x 55/4
Last part is conversion from into º plato
237 billon cells
Lager yeast, OG, 23 litres
0.75mil x 23,000 x 68/4 x 2
587 billon cells!!
Note both are considerably more than available from a single liquid yeast packet.( ~ 100 billion, if it is fresh )‏

23. Why you want even more yeast
Fast ferment
Simple test to see how attenuative your wort actually is. Ie what is the finish point?
Add small amount of wort to some of the propagated yeast
Make sure it is at least 2-3 times what is required
Ferment in a warm environment
Insurance against:
Incomplete fermentation
Note it does not have to be the same strain! Can use more robust and attenuative yeasts even. This is a whole new topic.
Fermentation defects remediation
Acetaldehyde
Diacetyl
etc

24. Process – Making yeast Finally lets get on with it:
Most important factor is how much yeast your are starting with
High count start > 100 billion cells << Easy Starter
Liquid yeast package
Save yeast slurry
Dry yeast ... only if you really really need to
Low yeast count << Harder Starter
Slants
Bottles
Small amounts kept under sanitised water

25. Making yeast - Easy Starter
Prepare wort
1gm of DME per 10ml water
Add nutrient
Boil
Do it in the emerlyser flask if you have one with some foil mostly over the top will sanitise it at the same time.
Cool down to pitching temp
Make sure propagating container is sanitised!

26. Making yeast - Easy Starer
Prepare yeast
Bring it up to room temperature
No need to “smack” wyeast packs, but no harm in doing so.
The nutrient in the smack packs will aid yeast growth.
If using saved yeast pour off non yeast liquid

27. Making Yeast – Easy Starter
Pitch yeast into starter wort
If not using a stirplate you need to aerate well. Oxygen is one of the greatest limiting factors of yeast growth.
Shaking up a container with a lid on it is a great way to get it aerated.
Don't put an airlock on the container ... we want the oxygen to be able to get in!
Add yeast to container

28. Making yeast – Easy starer
Grow yeast
Place in warm environment ( > 22 C < 28 C is best )‏
Don't let the temp drop below 20C if possible
Try to avoid large fluctuations
As always there is an alternative way
Grow yeast at temp you want to pitch
Growth rate will probably be a lot lower (especially at lager temps), but yeast will be more readily adapted to the fermentation environment
Also can pitch starter wort without fear off off flavours
I do not recommend this method

29. Making yeast – Easy starer
If not stirplating agitate often (the more the better)‏
Drives of CO2 and give more access for yeast to oxygen.
Not making beer!
You don't really want to see a normal fermentation taking place with huge krausen etc
Does not matter if there is no krausen at all
Can tell it is working by the changing colour of the starer wort. The lighter it is getting the more yeast.

30. Making yeast – Easy starer
Approximate growth rates for 100 billion cell starter
1ltr starter = ~ 172 billion cells
2ltr starter = ~ 230 billion cells
4ltr starter = ~ 305 billion cells
1ltr, then step up to 4ltr = ~ 400 billion cells
Step up means to add additional 3 ltrs to make total of 4 ltrs
Make sure wort additions are boiled then cooled down as per previous steps.
Growth phase should be completed in approx 24hrs.

31. Making yeast – Easy starter
After growth phase is complete cool down to 4C to ensure rapid flocculation occurs
Ideally better to slowly cool down if possible.
May need to leave up to 24hrs achieve this step
Pour of starter wort
Note you should taste some of the starter wort and make sure there are no infection issues
Also gives you a good idea of the types of esters etc the yeast is capable of producing.
Yeast is now ready to pitch!!

32. Making yeast – Harder starter
Starting with very small yeast counts has the following additional challenges:
Much higher risk of infection for first step due to very low yeast cell counts
Many smaller steps required to reach final pitchable quantities
Starter yield will probably be much lower

33. Making Yeast – Harder Starter
First step
Start with no more than 20ml of starter.
Pay particular attention to sanitation for this step.
Grow at same temp as easy starter.
May take up 3 days for any real noticeable activity
Should wait until sample is cloudy and clear evidence of yeast growth before starting subsequent steps

34. Making Yeast – Harder Starter
Step up in quantities of no more than 10x current starer size (x6 is even better)
Allow about 24hrs for each subsequent step
Will see more signs of fermentation as original yeast begins to ferment over time
A stirplate is required if you need to do this often (eg starting from slants etc).

35. Making Yeast - Stirplate
Magnetic stirbars are much easier to work with
Faster stir will result in better growth, but does not have to vortex
Dont leave it on the stirplate for excessive time
it will eventually have a negative effect on the yeast
24hrs is usually adequate

36. Alternative Methods Softdrink bottle method
Put yeast and wort in a sqeezable softdrink bottle.
Periodically squeeze CO2 out of bottle.
Let air back in.
Shake up again.
The more you do it the faster it will grow.
Reportedly this method can result in rapid yeast growth in very short timeframes

37. How much yeast do I have? Measure it! Yeast cell count
Need microscope amongst other things.
Sounds really painful, but some brewers do it.
Really need some training to do this properly.

38. How much yeast do I have? Approximation technique
Pour off ~ 80 ml into 100ml measuring flask when just completed.
Put into fridge and let flocculate out.
Wait for it to really compress down (takes about 2 day)‏
Not volume of compressed yeast (it should look much whiter by now)‏
Yeast will contain appox 4.5 billion cells per ml
Can now calculate appox amount in yeast starter.

39. Dry yeast

40. Dry Yeast Preparation of dry yeast
You need to hydrate in water before pitching!
Yeast that is not hydrated can not protect itself against absorption of excessive sugars results in signifigant loss of cells, and those that survive are the worse off for the experience.
Use pre-boiled water, cooled down to around 25C
About 1 cup per 8gms of yeast
Let it sit in water for about 30min prior to pitching.

41. Other References John Palmer – How to Brew
Brewing Network – Brew Strong podcast
Mr Malty – yeast pitch calculator
Wyeast website
Whitelabs website
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