1. Yeast Propagation & Storage
MBAA-Rocky Mountain District Meeting
March 24, 2004
Scandi Brew
Yeast Propagation & Storage By
Mike Cholerton
Sales & Technology Manager
Scandi-Brew
Alfa Laval Copenhagen A/S
© Alfa Laval

2. Yeast Propagation & Storage
© Alfa Laval
© Alfa Laval

3. Scandi Brew History goes back to 1901 as APH
Today the world’s leading supplier of yeast handling equipment and tank top systems
Supplied worldwide during the past 10 years:
130 Yeast propagation plants
42 Yeast storage plants
500 Yeast mixers
Since 1999 member of the Alfa Laval Group handling all “Yeast+” activities
© Alfa Laval
© Alfa Laval

4. Yeast Management ??? Ensures fresh supply of yeast
Rules and procedures for handling yeast in the brewery
Ensures fresh supply of yeast
In general healthy and productive yeast
Discharge of old and infected yeast
© Alfa Laval
© Alfa Laval

5. Yeast Management Propagation of fresh yeast Control infection
Key words
Propagation of fresh yeast
Control infection
Cold storage
Homogenisation
Low mechanical stress (pumps, mixing)
Low environmental stress (pressure, CO2)
Avoid contact with O2 unless the yeast is cold
Reduce CO2-content during storage
© Alfa Laval
© Alfa Laval

6. Why Yeast Propagation?
To control beer quality propagation and
thereby fresh yeast supply is necessary
In the fermentation process yeast mutates and change performance over time - as well as infection sooner or later becomes a problem
© Alfa Laval
© Alfa Laval

7. Fermentation problems with old yeast
Slow fermentation
Slow pH-drop causing infections to flourish
Slower rates of maltose & maltriose uptake
Higher level of SO2 and H2S
Prolonged diacetyl removal during maturation
Changed flocculation characteristics
© Alfa Laval
© Alfa Laval

8. Yeast Propagation
Producing - from a single cell - sufficient amount of yeast for fermenting a batch (brew or fermenter size) of wort
The yeast should be 100% uninfected
The yeast should be propagated with effective aeration in order to achieve a sufficient cell count
© Alfa Laval
© Alfa Laval

9. Propagation procedure
Since Emil Chr. Hansen isolated a single yeast cell at Carlsberg Laboratories in propagation has begun in the laboratory.
Last step before the propagation plant is the Carlsberg Flask.
In the CF wort can be sterilised, inoculated and trasferred out again under sterile conditions.
Carlsberg Flask
© Alfa Laval
© Alfa Laval

10. Single or multiple vessel plants
Batch production in a single vessel YPP
Continuous production in a multiple vessel YPP
Choise depends on propagation philisophy, frequency and investment
Cell counts are typically, respectively and million/ml
Difference in laboratory work
© Alfa Laval
© Alfa Laval

11. Propagation parameters
Temperature
High temperature will give fast propagation
But also cause stronger flavour impact from the propagated yeast
© Alfa Laval
© Alfa Laval

12. Propagation parameters
Aeration
The more effective the aeration - the higher the cell count
Continuous
By interval
Flow rate
Foam problems
© Alfa Laval
© Alfa Laval

13. Propagation parameters
Propagation Step
From sterile to sterile conditions 1:100 (1:200)
From sterile to wold wort conditions 1:10 (1:20)
© Alfa Laval
© Alfa Laval

14. Yeast Propagation Plant
Special features of SCANDI BREW® plant
Separate heating & cooling jackets on all vessels
In-vessel sterilisation of wort making a separate steriliser superfluous
All process and sterile air pipes and valves are easily cleanable and designed for steam sterilisation
Special designed aeration lance - fully integrated in the CIP and sterilisation system
© Alfa Laval
© Alfa Laval

15. Yeast Propagation Plant
Special features of SCANDI BREW® plant
Special outlet valve with no dead space
Remote controlled pressure regulation
100% headspace in 1-vessel plant, 40% in multiple vessel plant
Unique top plate design - 100% CIP’able
Sterilisable yeast mixer / CIP system for improved plant efficiency
Multi-purpose vessel design as yeast storage vessel
© Alfa Laval
© Alfa Laval

16. Yeast Propagation Plant
Propagation and all transfers are under sterile conditions
All pipes, valves & sterile air supply is 100% sanitary
SCANDI BREW® plant
© Alfa Laval
© Alfa Laval

17. Yeast Storage
To protect and improve yeast viability and vitality during storage
© Alfa Laval
© Alfa Laval

18. Yeast Storage Harvest asap Dispose of old & infected yeast
Yeast is cooled fast
Shorten storage time
Homogenise the yeast
Reduce pressure
De-gassed if possible
Avoid shear stress
Avoid infection
© Alfa Laval
© Alfa Laval

19. Yeast storage plant
© Alfa Laval
© Alfa Laval

20. Purpose of a specialised YSP
Gives flexibility in harvest and pitching
Possible to evaluate yeast before re-use
Homogenisation possible giving accurate pitching
Cold storage keeps metabolism and autolysis to a minimum
De-gassing increases viability
Offers the possibility of aeration prior to pitching
Storing in the cone of a CCF can be avoided
© Alfa Laval
© Alfa Laval

21. Yeast Mixing Yeast mixer / CIP system
with aeration or acid washing facility
Off centre or centre
SCANDI BREW® off centre mixer
© Alfa Laval
© Alfa Laval

22. Yeast Mixing + + + (stop/start) Fully CIP’able Acid washing & aeration
Off centre versus centre
Off centre +
Centre +
+ (stop/start)
Fully CIP’able
Acid washing & aeration
Effective mixing & gentle handling
Up to 50% solids
Above 50% solids
© Alfa Laval
© Alfa Laval

23. Yeast Mixing
Off centre
Function
© Alfa Laval
© Alfa Laval

24. Yeast Mixing Gentle product handling Flow-turbulence characteristics
© Alfa Laval
© Alfa Laval

25. Yeast Mixing
Centre
Function
© Alfa Laval
© Alfa Laval

26. Yeast Mixing Hollow shaft Self cleaning
Centre
Hollow shaft
Self cleaning
Fully CIP’able including bottom support
Aeration and acid wash possibility
Intermittent operation
© Alfa Laval
© Alfa Laval

27. Yeast Pumping
Gentle transfer of yeast to avoid mechanical stress with a sanitary and dedicated yeast pump
© Alfa Laval
© Alfa Laval

28. Yeast Management
Setting up standards for yeast handling and yeast handling equipment to achieve and maintain high product quality
Focus on quality is focus on yeast
Consistent production requires focus on yeast
© Alfa Laval
© Alfa Laval