Unit 2 - Lesson 2 - Cereals - The Malting Process Flashcards
1
Q
What is the first stage of the malting process?
A
Cereal delivery
2
Q
What must be checked during cereal delivery?
A
- Moisture content
- Grain size
- No broken grains
- No signs of infestation
3
Q
What is the second stage of the malting process?
A
Cereal storage
4
Q
How should cereal be stored to prevent issues?
A
In a cool, dry environment
5
Q
What is the purpose of the steeping process?
A
To soak cereal grains and start germination
6
Q
What occurs during the germination stage?
A
Steeped grain is transferred to a vessel with a perforated floor for air control
7
Q
How long does the germination process take?
A
Approximately four days
8
Q
What is the purpose of kilning in the malting process?
A
To remove moisture, stop germination, and add flavor
9
Q
What is the function of the perforated floor during germination?
A
To allow air to be blown through the bed of grain
10
Q
What occurs during the steeping process of cereal grains?
A
Cereal grains are steeped in water to increase moisture content for germination
Steeping involves submerging grains in water, leading to germination.
11
Q
What is the significance of the micropyle in the steeping process?
A
Most water enters the grain at the micropyle
The micropyle is a small opening in the grain where water absorption occurs.
12
Q
What is respiration in the context of steeping grains?
A
Grains consume dissolved oxygen and starch from endosperm, producing energy, carbon dioxide, and heat
This process supports the growth of the grain during steeping.
13
Q
How is heat managed during the steeping process?
A
Compressed air is blown into the steep water to mix the grain and prevent heat buildup
Mixing helps maintain consistent temperature and oxygen levels.
14
Q
What is a typical duration for the first wet period in steeping?
A
4 to 8 hours
This duration allows the grains to absorb sufficient water.
15
Q
What happens after the wet period in the steeping process?
A
The steep water is drained, initiating the first air rest
During the air rest, grains continue to germinate and require oxygen.
16
Q
What is the role of fresh air during the air rest?
A
Fresh air supplies oxygen and removes carbon dioxide produced by respiring grains
This prevents suffocation of the grains.
17
Q
How many wet periods and air rests are typically involved in steeping?
A
2-3 wet periods and 2-3 air rests
This cycle occurs over approximately 48 hours.
18
Q
What is the change in moisture content of the grain during steeping?
A
Increases from about 12% to between 42% and 45%
At this moisture content, grains begin to grow.
19
Q
What is the first sign of germination in cereal grains?
A
A small rootlet, known as a chit, appears at the embryo of the grain
The chit indicates the beginning of the germination process.
20
Q
What are the typical shapes of steeping vessels?
A
Conical or flat-bottomed
21
Q
What are the key features of steeping vessels?
A
- Filling and emptying facilities
- aeration
- carbon dioxide extraction
22
Q
How is grain added to a steeping vessel?
A
Via the top of the steeping vessel
23
Q
What is used to suppress dust during the transport of cereals?
A
Water sprays
24
Q
How is grain distributed in a conical steeping vessel?
A
Spread over a cone
25
What mechanism is used to spread grain in a flat bottom tank?
Giracleur
## Footnote
Rotating arms with blades
26
Where is the water inlet typically located in a steeping vessel?
At the bottom of the steeping vessel
27
What controls the water level in a steeping vessel?
Sensors inside the steep tank and valves at the inlet
28
What happens to light materials like straw during the steeping process?
They float on the water and are removed through the overflow
29
What is the purpose of the perforated screens at the bottom of steeping vessels?
Allow water to be drained away, leaving the grain behind
30
How does the size of the perforated screen differ between conical and flat bottom vessels?
Conical vessels have small screens; flat bottom vessels have the entire floor perforated
31
What is the area under the perforated screen called?
Plenum
32
How does water usage compare between conical and flat bottom steeping vessels?
Flat bottom vessels use more water per tonne of malt
## Footnote
Plenum is quite large and must be filled with water before the water reaches the grain
33
What is done to replace the dissolved oxygen in steep water?
Compressed air is blown into the steep water
34
How is aeration achieved in a conical vessel?
Using an aeration ring or nozzles in the wall
35
How is aeration provided in a flat bottom vessel?
Using pipes under the vessel floor
36
What gas must be extracted during air rests to prevent suffocation of the grain?
Carbon dioxide
37
What mechanism is used to draw fresh air through the grain in steeping vessels?
Fans
38
Which type of steeping vessel has a more even airflow?
Flat bottom steep vessels
39
What is the duration of germination for steeped grain?
Between three and six days
## Footnote
This is done in a controlled environment to stimulate enzyme production.
40
What is the process called that refers to the changes in grains during germination?
Modification
## Footnote
This process should be as complete and even as possible.
41
What are the two main environmental factors controlled during germination?
* Temperature of the grain bed
* Moisture content of the grain
42
What is the function of enzymes during germination?
Break down the protein matrix and cell wall components to access starch.
43
What hormone does the embryo produce during germination?
Gibberellic acid
44
Where is α-amylase produced and what is its function?
Produced by the aleurone layer; breaks down starch into glucose chains of various sizes.
45
Where is β-amylase produced and what is its function?
Present in endosperm and activated during germination; breaks down long glucose chains into maltose.
46
What does limit dextrinase do during germination?
Breaks down branch points in glucose chains.
47
What are β-glucanases and pentosanases responsible for?
Breakdown of β-glucan and pentosan in endosperm cell walls.
48
What is the function of proteases in the germination process?
Breakdown of the protein matrix in endosperm cells.
49
What happens to the endosperm as barley grows during germination?
It becomes soft and can be rubbed into a paste with no hard lumps.
50
What is the term used for barley after it has been modified and is ready to transfer to the kiln?
Green malt
51
What physical change indicates that the endosperm is well modified?
It rubs into a paste with no hard lumps.
52
True or False: The starch granules in the endosperm are easily accessible without enzyme action.
False
53
What is the purpose of germination?
To stimulate the grain to produce important enzymes for sugar conversion
54
What makes up an endosperm cell?
* Cell walls made of β-glucan and pentosan
* Protein matrix embedded with starch granules
## Footnote
large and small starch granules
55
What is the role of gibberellic acid?
This hormone stimulates enzyme production in the aleurone layer.
56
What is a germination vessel?
A germination vessel is a container that holds a batch of germinating grain for between three and six days.
## Footnote
Typically circular or rectangular
57
What is a Saladin box?
A Saladin box is a type of rectangular germination vessel invented by Charles Saladin in the 1800s.
58
What are the common design features of germination vessels?
* Filling and emptying facilities
* A perforated floor
* Fans and air recirculation
* Turning machines
59
How is grain filled in a Saladin box?
A conveyor transports steeped grain along the length of the box and spreads it into multiple piles for the turning machine to evenly flatten across bed
60
How is grain filled in a circular germination vessel?
Steeped grain comes down a chute at the center and is directed to a horizontal screw that spreads it across the floor.
61
What is the purpose of the perforated floor in a germination vessel?
The perforated floor allows air to be forced through the grain, keeping it cool and preventing overheating.
62
How is temperature controlled during germination?
Warm air from above the grain bed can be recirculated back into the air being applied under the grain bed using recirculation louvers.
63
What is the function of turning machines in germination vessels?
Turning machines break up tangled rootlets in the grain, ensuring proper airflow and easy emptying of the vessel.
64
How often do turning machines operate?
Turning machines typically move through the batch every 8-12 hours.
65
What is an alternative type of germination vessel?
A rotating drum can be used to gently turn the green malt, preventing rootlet matting while providing airflow and temperature regulation.
66
What is the typical depth of the grain bed?
Between 2 and 3 m
67
Why must the grain be distributed evenly?
To ensure even airflow through grain
68
How is grain emptied from a circular germination vessel?
The horizontal screw is reversed and pulls green malt to a chute in the middle of the vessel
69
How is grain emptied from a Saladin box?
The turning machine transports green malt to a conveyor in the floor or an elevator that lifts the green malt to a conveyor above the malt box
70
What role do fans play during germination?
Fans blow saturated air through the germinating grain
71
How does the air get saturated and why?
Humidification sprays mist the air ensuring it is saturated with moisture to prevent moisture loss from the grain.
72
How does a turning machine operate?
Multiple vertical helical screws rotate to pull germinating grain from bottom to top of the bed
73
What is the primary aim of kilning?
* To reduce the moisture content of the green malt so it can be safely stored
* Preserve the enzymes the grain has produced during steeping and germination
* Add flavour to the malted cereal
* Complete the kilning process in time for the next batch to be kilned
74
What is the air-on temperature in the kilning process?
The temperature of the air being forced through the malt bed
75
What does the air-off temperature refer to?
The temperature of the air coming off the bed of green malt
76
What does the air-off relative humidity indicate?
the moisture removed from the green malt
77
How many phases are there in the kilning process and what are they?
Four phases
* Free drying
* Forced drying
* Curing
* Cooling
78
What is the moisture content of green malt at the start of kilning?
Typically between 43 and 45%
79
What temperature range is used during the free drying phase and why?
55-65°C
Prevents enzyme damage
80
What happens at the break point during the free drying phase?
The air-off temperature begins to increase and air-off relative humidity decreases
## Footnote
This indicates the end of the free drying phase.
81
What is the temperature range increased to during the forced drying phase?
65-75°C
82
What is the purpose of the curing phase?
To determine the final moisture
83
What temperature range is applied during the curing phase?
75-85°C
84
What indicates the end of the curing phase?
When the air-off temperature reaches a set point
85
What is the purpose of the cooling phase in kilning?
To cool the malt so it can be safely stored
86
When does the cooling phase finish?
When the air-off temperature is less than 30°C
87
What is the purpose of air-on air?
To dry the green malt and cool the air
88
What is the air-off relative humidity?
The humidity of the air coming off the malt bed
## Footnote
It indicates the moisture removed from the green malt.
89
Why is it called the free drying phase?
green malt freely releases moisture from its surface into the air
90
What does the high moisture content tell us about the green malt enzymes?
They can be damaged by excessive heat
91
How long does the free drying phase last?
6-8 hours
92
Why does the break point occur?
all the free surface moisture has been removed from the green malt
93
How long does the forced drying phase typically last?
8-10 hours
94
Why is the temperature increased during the forced drying phase?
to force the remaining moisture out of the inside of the grain kernel
95
What is the typical final moisture range of the malt?
4-6%
96
How long does the curing phase typically last?
30 min to 1 hour
97
How is the malt cooled during the cooling phase?
Ambient air is blown through the malt bed
98
What is the typical design of kilning vessels?
Kilning vessels are typically circular in design although sometimes they are rectangular.
99
What features do kilning vessels share with germination vessels?
* Filling and emptying facilities
* Perforated floor
100
Why do kilning vessels not have turning machines?
Because the rootlets produced by grain during germination dry out and fall off during the kilning process.
101
How deep is the grain bed in a typical kiln?
Approximately 1 m deep.
102
What is the primary method used to heat the air in kilns?
All kilns are heated by burning some sort of fuel, typically natural gas or oil.
103
How does a directly heated kiln function?
The air is heated directly by the combustion gasses of the fuel.
104
What is NDMA and why is it significant in malting?
N-Nitrosodimethylamine (NDMA) is a potential carcinogen produced from reactions between nitrous oxides and nitrogen-containing compounds in malt.
105
What NDMA levels are expected in malt?
NDMA levels below 1.0 µg/kg are expected.
106
Describe how an indirectly heated kiln operates.
A fuel is burned but not used to heat the air directly
107
What is the role of fans during kilning?
Air is blown through the green malt
108
What happens to the air at the end of the kilning process?
The air coming off the grain bed is hot and relatively dry.
109
What is the purpose of recirculation louvers during kilning?
To control the proportion of air that is recirculated during kilning.
110
Why are heat exchangers used in kilning?
To capture valuable heat from the exhaust air and heat the incoming ambient air.
111
What materials are typically used to construct heat exchangers?
Heat exchangers are typically made from glass or stainless steel.
112
What is a germinating and kilning vessel (GKV)?
A vessel where the germination and kilning processes are combined, eliminating the need to move grain between vessels.
113
What were the first large scale malting houses known as?
Floor maltings.
114
How was grain treated in early floor maltings?
Grain was received into the top and dropped into deep cisterns for steeping, then piled onto a stone floor for germination.
115
What thickness of grain layers was required for sufficient temperature control during germination?
Thin layers of 8-15 cm.
116
How was room temperature controlled in early malting houses?
By opening vents in the walls and manually turning grain
117
What limitation did early kilning processes face?
Limited air flow due to a lack of fans to blow hot air.
118
What architectural feature is associated with the distinctive outline of malt whisky distilleries in Scotland?
Pagoda roofs.
119
Are there still floor maltings in use today?
Yes, there are still a few, such as the one at Highland Park Distillery in Orkney.
120
What is the trend in malting production today?
Most of the malt used today is made in large scale commercial malting plants.
121
What is peat?
Decayed plant material or organic matter that forms over thousands of years.
122
What is the key ingredient for producing peated malt?
The smoke produced by burning peat.
123
How is peat burned to produce smoke?
In a separate unit (firebox) under controlled conditions to produce smoke and minimize flames.
124
What are the compounds known as that provide flavour and aroma in peated malt?
Phenols.
125
What is the required moisture content of peat for burning?
50-60%.
126
Why is controlling peat moisture level essential?
Smoke is required when burning peat, not flames.
127
What contributes to the unique characteristics of a peat smell?
High levels of organic material in peat.
128
List some flavour compounds found in peat.
* Phenol
* Cresol
* Eugenol
* Guaiacol
129
What type of malted wheat is typically used in distilling?
Pale and lightly kilned malted wheat
## Footnote
Malted wheat used in food is typically darker and imparts a sweet flavor.
130
What influences the selection of wheat for malting?
The nitrogen (protein) content
## Footnote
Wheat nitrogen is typically less than 1.60%.
131
Which type of wheat is good for malt used in alcohol production?
Soft wheat
132
What is the typical moisture level for steeping wheat?
42%
133
At what temperature is wheat germinated?
Typically lower than 16˚C
134
How long is wheat usually in the germination vessel before kilning?
Up to five days
135
What is a notable characteristic of wheat malts in terms of fermentation?
High levels of free amino nitrogen (FAN)
136
What is a key enzyme characteristic of rye malts?
High levels of α- and β-amylase enzymes
137
Why must rye be treated similarly to wheat during processing?
Rye has no husk
138
How does rye behave during the steeping process?
Rye rapidly takes up water
139
What is the germination duration for sorghum malt?
Four to six days
140
What happens to α- and β-amylase enzyme levels during the germination of sorghum malt?
They increase
141
What is the typical moisture content of malt distilling malts?
Around 4.5%
## Footnote
Moisture content above 7.0% can complicate milling in conventional roller mills.
142
What moisture content range is typical for grain distilling malts?
Between 5% and 6%
## Footnote
This higher moisture is manageable for grain distilleries using hammer mills.
143
Why must malt be dried?
* To stabilize it for long-term storage
* To allow it to be milled in conventional roller mills
144
What is the extract of distilling malt?
The measure of the total material available from the malt for the yeast during fermentation.
145
What does a higher extract in malt indicate?
A higher specific gravity of the wort produced.
146
What is the main concern for grain distillers regarding extract levels?
They are primarily focused on providing enzymes and soluble nitrogen/FAN.
147
What do friability and homogeneity indicate about malt?
How easily the malt will mill and how evenly it has been modified.
148
What friability percentage indicates malt is suitable for malt whisk(e)y production?
Greater than 86%
149
What is the typical friability specification for grain distilling malt?
Greater than 80%
150
What does a fermentability test measure?
The percentage of extract that can be fermented by yeast.
151
What is the fermentability equation?
152
What is the constant factor used to calculate alcohol yield in litres of alcohol per tonne (LA/t)?
6.06
153
What is the PSY equation?
154
What does PSY stand for?
Prediction of the expected spirit yields
155
What is the typical PSY specification for most malt distillers?
> 405 LA/t
156
In a good year, what is a typical PSY specification?
> 415 LA/t
157
What does the average PSY for malt depend on?
Quality of the barley harvested
158
What are the two main enzymes involved in mashing?
* α-amylase
* β-amylase
159
What is diastatic power (DP) a measure of?
The malt's ability to degrade starch.
160
What enzyme potential is expected for malt distilleries?
Greater than 75 °IoB (240 °WK EBC) DP
161
What enzyme potential is expected for grain distilleries?
* 165-200 °IoB (500-600 °WK EBC) DP
* DU greater than 65°IoB/EBC
162
What do soluble nitrogen and FAN provide during fermentation?
Nutritional sources for yeast.
163
Why are soluble nitrogen and FAN particularly important for grain distillers?
The raw cereal contributes little soluble nitrogen and FAN.
164
What does the phenol level in malt indicate?
The level of smoky aromas in the finished spirit.
165
What is required for non-peated whisk(e)y regarding phenol levels?
The malt must be free of phenol.
166
What is the malt total phenols range for light peating level?
1-5 mg/kg
167
What is the malt total phenols range for medium peating level?
6-15 mg/kg
168
What is the malt total phenols range for heavy peating level?
15-40 mg/kg
169
What is the malt total phenols range for very heavy peating level?
40-55 mg/kg
170
What is ethyl carbamate (EC)?
A trace compound found in various foods and alcoholic beverages that is carcinogenic.
## Footnote
EC is a major food safety concern for distillers due to its cancer-causing properties.
171
How is ethyl carbamate (EC) produced?
Created during the distilling process from precursors produced by some malting barley varieties.
## Footnote
Distillers control EC levels by sourcing malt from barley varieties that have low or null potential to produce these precursors.
172
What measures do distillers take to control ethyl carbamate (EC) levels?
They purchase malt made from barley varieties with low or null potential to produce precursors.
## Footnote
This includes specifying non-GN producing varieties.
173
What is glycosidic nitrile (GN)?
A precursor to ethyl carbamate produced by some malting barley varieties.
## Footnote
Distillers often specify the use of non-GN producing varieties to mitigate risks.
174
What is the typical limit for glycosidic nitrile (GN) levels in malt?
Below 0.2 g/t.
## Footnote
Distillers enforce strict limits on GN levels to control EC production.
175
What is NDMA?
N-Nitrosodimethylamine, a potential carcinogen formed during the kilning of green malt.
## Footnote
It arises from the reaction of nitrogen oxides with nitrogen-containing compounds in the malt.
176
How is NDMA produced in malt?
During kilning due to the presence of nitrogen oxides, especially in direct fired kilns.
## Footnote
Indirectly fired kilns can also produce NDMA if supplied with contaminated air.
177
What NDMA levels do most distillers expect in malt?
Below 1.0 µg/kg.
## Footnote
This expectation reflects the need to control NDMA presence due to its carcinogenic properties.
178
What physical characteristics do distillers look for in malt?
Evenly sized grains and well-formed, intact husks.
## Footnote
These characteristics ensure consistent crushing and protect the malt from physical damage.
179
Why are husks important in malt distilling?
They protect the malt from physical damage during transportation and conveying.
## Footnote
The integrity of the husk is crucial for the wort separation process.
180
What concerns do distillers have regarding dust and fine materials in malt?
High levels can generate dust clouds during conveying, posing safety hazards and reducing yield.
## Footnote
Managing dust is essential for both safety and efficiency in malt production.
181
What is the typical moisture content of malt distilling malt?
4.5-5.5%
## Footnote
This indicates the range of moisture present in malt distilling malt.
182
What is the typical moisture content of grain distilling malt?
< 6.5%
## Footnote
This shows that grain distilling malt generally has a higher moisture content than malt distilling malt.
183
What is the soluble extract percentage for typical malt distilling malt?
77.0-79.0%
## Footnote
This value reflects the sugar content that can be extracted from malt distilling malt.
184
What is the fermentability percentage of typical malt distilling malt?
> 87.5%
## Footnote
This indicates a high level of fermentability in malt distilling malt.
185
What is the range for fermentable extract in typical malt distilling malt?
67.0-69.0%
## Footnote
This represents the portion of extract that is fermentable in malt distilling malt.
186
What is the predicted spirit yield for malt distilling malt in LA/t?
405-418 LA/t
## Footnote
This value indicates the expected yield of spirit per ton of malt distilling malt.
187
What is the total nitrogen percentage on a dry weight basis for typical malt distilling malt?
< 1.65% dwb
## Footnote
This indicates the nitrogen content in malt distilling malt.
188
What is the total nitrogen percentage on a dry weight basis for typical grain distilling malt?
> 1.8% dwb
## Footnote
This shows that grain distilling malt typically has a higher nitrogen content than malt distilling malt.
189
What is the soluble nitrogen percentage on a dry weight basis for typical malt distilling malt?
0.55-0.65% dwb
## Footnote
This value reflects the soluble nitrogen content in malt distilling malt.
190
What is the soluble nitrogen ratio (SNR) for typical malt distilling malt?
36-42%
## Footnote
This indicates the ratio of soluble nitrogen in malt distilling malt.
191
What is the range of free amino nitrogen (FAN) in typical malt distilling malt?
130-160 mg/L
## Footnote
This reflects the concentration of free amino nitrogen in malt distilling malt.
192
What is the free amino nitrogen (FAN) for typical grain distilling malt?
> 175 mg/L
## Footnote
This indicates a higher FAN content in grain distilling malt compared to malt distilling malt.
193
What is the friability percentage for typical malt distilling malt?
86-95%
## Footnote
This shows the ability of malt distilling malt to break down during mashing.
194
What is the friability percentage for typical grain distilling malt?
> 80%
## Footnote
This indicates that grain distilling malt also has good friability.
195
What is the homogeneity percentage for both malt and grain distilling malts?
> 98%
## Footnote
This indicates a high level of consistency in both types of malts.
196
What is the maximum residual wort β-glucan for typical malt distilling malt?
< 130 mg/L
## Footnote
This value indicates the amount of β-glucan left in the wort from malt distilling malt.
197
What is the diastatic power (DP) for typical malt distilling malt?
> 75 °IoB
## Footnote
This reflects the enzyme activity in malt distilling malt.
198
What is the diastatic power (DP) for typical grain distilling malt?
> 165 °IoB
## Footnote
This indicates a significantly higher enzyme activity in grain distilling malt.
199
What is the Dextrinising Units (DU) for typical grain distilling malt?
> 65 °IoB
## Footnote
This indicates the ability to convert starches into dextrins in grain distilling malt.
200
What is the glycosidic nitrile content for both malt and grain distilling malts?
< 0.2 g/t
## Footnote
This shows that both types of malts have a low level of glycosidic nitrile.
201
What is the NDMA content for both malt and grain distilling malts?
< 1.0 µg/kg
## Footnote
This indicates the low levels of NDMA found in both types of malts.
