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IBD General Certificate > Unit 4 - Lesson 1 - Fermentation > Flashcards

Unit 4 - Lesson 1 - Fermentation Flashcards

1
Q

What causes the density of unfermented liqours?

A

Almost entirely due to sugars

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2
Q

What are measurement instruments for gravity?

A

Brix
Bailing
Plato
Specific gravity saccharometers

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3
Q

Declared gravity

A

1.045 - 1.080

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4
Q

Yeast fermentation turns carbs into…

A 
Alcohol
Biomass
Congeners (flavor compounds)
CO2
Heat
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5
Q

What happens to the density of fermenting spirits?

A

Density decreases - more alcohol, less sugar, CO2 released, etc

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6
Q

What does efficient fermentation rely on?

A

Carb source
Healthy yeast
Suitable, Clean fermentation vessel
Temp control if outside is variable

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7
Q

What are the 2 key components for fermentation?

A
  1. Sugar rich liquor

2. Suitable yeast - for conversion and flavor compounds

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8
Q

What do you need to do prefermentation?

A

make sure the temp is cooled to 15-25°C

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9
Q

What is the equation for yeast turning glucose into alcohol?

A

1 molecule of Glucose
2 molecules of Alcohol
2 molecules of CO2
Heat (exothermic)

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10
Q

What are the primary sugars in cereals?

A

Glucose
Maltose (2 glucose)
Maltotriose (3 glucose)
Dextrins (4+ glucose)

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11
Q

What are sugars in molasses?

A

Glucose
Fructose
Sucrose

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12
Q

Primary sugar in agave?

A

Fructose

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13
Q

4 phases of fermentation?

A

Phase 1 - Inoculum - adding yeast
Phase 2 - Growth
Phase 3 - Fermentation
Phase 4 - Post-Fermentation

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14
Q

What is key in Phase 1 fermentation - inoculum or adding yeast?

A

Early filling to avoid micro contamination

Make sure nutrients are available

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15
Q

Example of low versus high inoculation?

A

Wine - 14 days
Whiskey - 48 hours
Higher inoculation lead to faster fermentation

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16
Q

Why is Phase 1 called the lag phase?

A

yeast adjusting to new enviro and preparing to start growth and cell division processes

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17
Q

When does Phase 2 - Growth happen?

A

Few hours after inoculation, anywhere between 3 and 24 hours,

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18
Q

What is a by-product of yeast growth?

A

amyl alcohol and is a congener

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19
Q

Describe Phase 2 Fermentation

A

Yeast multiply fast
Alcohol produced
Specific gravity decreases
Once O2 consumed, yeast slow or dies

20
Q

What happens in Phase 3 of fermentation?

A

O2 depleted so anaerobic digestion begins
Most vigorous phase
Most heat produced
Flavor compounds produced at very low concentrations

21
Q

What is a benefit during Phase 3 - Fermentation?

A

If there was no previous presences of microbial contaminants - at this stage it is unlikely there will be since more ABV inhibits bacteria

22
Q

What happens in Phase 4 Fermentation

A

Post-Fermentation Stage
Fermentation - stops no more carbs
Temps drop
Yeast cells stay suspended but inactive

23
Q

What needs to happen in Phase 4 and why?

A

Move to distillation phase quickly to avoid microbal contamination

24
Q

What is measured during fermentation?

A
  1. temperatures throughout
  2. pH profile
  3. Specific gravity
  4. Ethyl alcohol and other alcohol profiles
  5. sometimes changes in sugar content
25
Q

How do distillers measure conversion of raw material into alcohol (individual fermentation yield)?

A

Liters of alcohol per ton of raw material

26
Q

Basic material requirements for a fermenter?

A
  1. strong enough to hold liquid

2. Easy to clean and repair

27
Q

What are the key processes for a fermenter choice?

A

Filling
Emptying
CO2 extraction & removal
Potential agitation

28
Q

What are the main vessels?

A

Stainless
Mild Steel
Wood
Concrete

29
Q

Benefits/Issues of a stainless vessel?

A
  1. Durable - long lasting
  2. Resistant to acid corrosion
  3. Easily build to spec
  4. Easy to install
    Problem - susceptible to chloride corrosion & expensive to install
30
Q

Benefits/Issues of a mild steel vessel?

A

Cheaper to install than stainless
Easy to build to spec
Easy for CIP and other controls
Problem- very susceptible to corrosion

31
Q

Benefits/Issues of a wood vessel (larch or Oregon pine)?

A

Usually for traditional ferments
Flavor retained
Problem - expensive to install, can leak or dryout, higher maintenance and limited size

32
Q

What are wood fermenters usually built from?

A

Larch &

Oregon pine

33
Q

Benefits/Issues of a concrete vessel?

A

Huge capacity

Hard to install

34
Q

Where would concrete fermenters be valuable?

A

Fuel Alcohol business due to huge capacity

35
Q

When does anaerobic fermentation start?

A

when CO2 layer fully covers the fermentation

36
Q

What is a challenge for open fermenters?

A

Could overflow in Phase 3 need space at the top

37
Q

Design considerations?

A
  1. Full discharge of ferment
  2. Auto cleaning
  3. Steam sanitation in case of residual solids
  4. Top or bottom filling with auto controls
  5. Agitation if required
  6. Secured lids - helps with AD and prevents contamination
38
Q

Considerations for fermenters in warm climates?

A

Cooling jackets to keep below 35°C

39
Q

What is a distillers optimize process condition?L

A
  1. Optimal gravity - at start
  2. Inoculation rate for the right yeast
  3. Follow all cleaning and temp controls
  4. Quick filling and emptying for efficiency
  5. Ideal feedstock for specific spirits distilled
40
Q

What is the main bacterial contaminant?

A

Lactic acid either from raw material or yeast

41
Q

What can bacteria do to a fermentation?

A

Reduce or raise acidity and cause off flavors

42
Q

Generally what why do distillers want to keep out wild yeast?

A
  1. Found everywhere
  2. Ramp during aerobic stage to compete agains chosen yeast
  3. Reduces yield
  4. Unwanted flavors
43
Q

Where does microbial contamination originate?

A
  1. Unfermented liquor
  2. Yeast supply
  3. Plant and/or equipment not cleaned properly
44
Q

Two groups of bacteria?

A
  1. the useful type

2. those that cause serious issues

45
Q

Why would a distiller want to add bacteria?

A
  1. help generate sour mash in whisky
  2. Secondary fermentation
  3. Lactic acid can add fruity and estery notes to whisky
46
Q

What are the ways to ensure an efficient fermentation?

A
  1. Correct volume of wort
  2. Correct fill level
  3. Correct quantity yeast
  4. Specified yeast for flavor profile
  5. Temps not over 35°C
  6. Clean plant & equipment
  7. Add yeast early as possible

IBD General Certificate (52 decks)

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