Fermentation

Management

Flo Vialan

(Director of Brewing - Purity Brewing Co)

C6H12O6 2C2H5OH + 2CO2

Is it really as simple as that?

Topics Covered:

Fermentation Vessels

Stages of Fermentation

Fermentation Controls

Fermentation Flavours

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Trouble

Q&A

High Alcohol

Esters

Diacetyl

Sulphur

Shooting--

Cl sr

Fermentation Vessels

Traditional Open Fermenters

vs

Close Fermenters

Stages of FermentationGravity Temp Y/C DO2

60

45

30

15

00 23 45 68 90

look at your

Fermentation Control:

‘Please have a look at your Handouts’

Fermentation Flavours:

- Higher Alcohols -(Also known as Fusel Oils)

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Can give headaches

Is the by product of:

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Low levels produced by yeast in normal conditions

High levels produced when amino nitrogen depleted

- Factors that increase yeast growth increase Fusel Oil production

Compounds Threshold (ppm) Flavour description

n-

Propanol

600 Alcohol sweet

Isobutan

ol

100 Solve

ntIsoamyl alcohol 50-

65

Alcoholic, banana

Amyl alcohol 50-

70

Alcoholic, solvent

2-Phenyl ethanol 40 Rose

s

- Esters -90 Identified. Give Fruity and Flowery Flavours

Most Important Are:

- Production related to concentration of precursors and yeast strain

- Amount of acid and alcohol present:

Increased by:

- High Wort

Gravity

- Higher

Temperatures

- Zinc

Decreased by:

- Top pressure on the

vessel

- Deep vessels

- Yeast

Compound Threshold level (ppm) Flavour description

Ethyl acetate 30 Fruity, solvent-like

Isoamyl acetate 1.2 Banana, pear

Phenyl ethyl acetate 3.8 Roses, honey

Ethyl hexanoate 0.2

3

Apple, fruity, sweetish

Ethyl octanoate 0.9 Apple anissed

- Diacetyl -Butterscotch flavours

Created during the synthesis of protein when the

wort is depleted of FAN

Yeast will reprocess to ‘flavourless’ acetoin

Also a sign of anaerobic infection

Low levels accepted in ales, a sin in lager beers

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- Sulphur -!

Sulphytic (struck matches), sulphidic (eggs)

Will depend on the yeast strain used

Will increase with high gravity, sulphate and temperature

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- Acetyldehyde -

In pathway from Glucose to Ethanol

Produced early in fermentation but mopped up by yeast in

maturation

Flavour of ripe apples

Typical flavour in young, green beer

Amount is dependent on strain

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FlavourSummary:

Trouble Shooting:

+

Too Slow

Too Fast

Over Attenuation

Under Attenuation

Mutation:

Fermentation Management

The End

Any Questions…?