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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
How do distillers measure conversion of raw material into alcohol (individual fermentation yield)?
Liters of alcohol per ton of raw material
26
Basic material requirements for a fermenter?
1. strong enough to hold liquid | 2. Easy to clean and repair
27
What are the key processes for a fermenter choice?
Filling Emptying CO2 extraction & removal Potential agitation
28
What are the main vessels?
Stainless Mild Steel Wood Concrete
29
Benefits/Issues of a stainless vessel?
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
Benefits/Issues of a mild steel vessel?
Cheaper to install than stainless Easy to build to spec Easy for CIP and other controls Problem- very susceptible to corrosion
31
Benefits/Issues of a wood vessel (larch or Oregon pine)?
Usually for traditional ferments Flavor retained Problem - expensive to install, can leak or dryout, higher maintenance and limited size
32
What are wood fermenters usually built from?
Larch & | Oregon pine
33
Benefits/Issues of a concrete vessel?
Huge capacity | Hard to install
34
Where would concrete fermenters be valuable?
Fuel Alcohol business due to huge capacity
35
When does anaerobic fermentation start?
when CO2 layer fully covers the fermentation
36
What is a challenge for open fermenters?
Could overflow in Phase 3 need space at the top
37
Design considerations?
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
Considerations for fermenters in warm climates?
Cooling jackets to keep below 35°C
39
What is a distillers optimize process condition?L
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
What is the main bacterial contaminant?
Lactic acid either from raw material or yeast
41
What can bacteria do to a fermentation?
Reduce or raise acidity and cause off flavors
42
Generally what why do distillers want to keep out wild yeast?
1. Found everywhere 2. Ramp during aerobic stage to compete agains chosen yeast 3. Reduces yield 4. Unwanted flavors
43
Where does microbial contamination originate?
1. Unfermented liquor 2. Yeast supply 3. Plant and/or equipment not cleaned properly
44
Two groups of bacteria?
1. the useful type | 2. those that cause serious issues
45
Why would a distiller want to add bacteria?
1. help generate sour mash in whisky 2. Secondary fermentation 3. Lactic acid can add fruity and estery notes to whisky
46
What are the ways to ensure an efficient fermentation?
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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