Yeast Management

Question 1

Name 3 stresses that can effect brewing yeast

Answer 1

Temp shock
Alcohol toxicity
Hydrostatic pressure

Question 2

List 2 yeast viability tessts

Answer 2

Plate / slide culture

Specific dyes

Question 3

List 2 vitality tests

Answer 3

Slurry pH

Specific Oxygen Uptake test (OUR)

Question 4

Explain why yeast glycogen levels need to be high during storage

Answer 4

Used as a backup energy source help build cell walls during post pitch O2 pickup.

Question 5

What are the main aims of yeast pitching

Answer 5

Minimize lag phase

Pitch consistent levels of viable cells

Question 6

Describe method of acid-washing yeast

Answer 6

Using 75% phosphoric acid (1 part acid, 2 parts h2o)
Chill yeast and acid to 2c
Slowly dose in acid mix
Measure pH after stirring. Shot for 2.3
Use within 4 hours

Question 7

3 disadvantages of acid washing

Answer 7

Strain specific. Some cant handle the added stress

Must be used within a 4 hour window

Can cause decrease in viability