Unit 1 - Malt - Germination Flashcards
What is the main function of enzymes during germination?
To break down structures of the endosperm, including cell walls and starch granules
Enzymes involved include β-glucan solubilase, α-amylase, and β-amylase.
What are the two forms of starch found in barley granules?
- Amylose
- Amylopectin
What is the role of β-glucan solubilase in germination?
Breakdown of protein links that keep β-glucan chains rigid and insoluble
What must be degraded to expose starch granules during germination?
The protein matrix surrounding the starch granules
What are the two types of proteases involved in protein breakdown?
- Endoproteases
- Exoproteases
What is the significance of the balance in protein breakdown during germination?
Too little leads to incomplete modification; too much destroys proteins needed for beer foam.
What enzymes are responsible for starch breakdown?
- α-Amylase
- β-Amylase
- Limit dextrinase
Fill in the blank: The enzyme that converts phytic acid to phosphate in barley is called _______.
Phytase
What is the main function of lipases during germination?
Breakdown lipids to produce fatty acids for energy and new plant cells
What compound does lipoxygenase oxidize, leading to stale beer flavor?
Linoleic acid
What is gibberellic acid (GA) and its role in germination?
A hormone that stimulates enzyme production during germination
List two properties that increase due to gibberellic acid (GA).
- Extract
- Soluble proteins
List two properties that decrease due to gibberellic acid (GA).
- Germination time
- Colour
What is the traditional method of germination called?
Floor maltings
What is the function of the helical screws in modern Saladin boxes?
To turn the grain bed and prevent matting
What temperature range is typically maintained in the grain bed during germination?
16-21˚C
What is the effect of moisture on germination and enzyme activity?
Increasing moisture increases the rate of modification and enzyme activity.
Fill in the blank: The acrospire growth test is used to measure the extent of _______ during germination.
Modification
What does a length measurement of > 1 for acrospires indicate?
Over modification of the kernels
What are two quality checks that can be performed during germination?
- Moisture content analysis
- Visual analysis
What is the role of temperature control during germination?
To maintain optimal enzyme activity and prevent overheating
What is the consequence of high CO2 levels during germination?
Reduces the rate of germination
What is the purpose of water spray nozzles during germination?
To maintain bed moisture
What is the significance of the protein matrix density in barley grains?
Higher density can make grains resistant to protein-degrading enzymes.
What is the primary purpose of α-amylase during starch breakdown?
To randomly break glucose links within the starch molecule.
What is the role of limit dextrinase in starch breakdown?
To break the branch points of amylopectin, creating shorter chains.
What is the effect of climatic conditions on amylase levels in barley?
Can affect the production of α- and β-amylases.
What range indicates that acrospires are either dead or growing slowly?
0-1/4
Acrospires are the shoots that emerge from the germinating grain.
What is the significance of having acrospires the same length?
It helps ensure the finished malt is uniform across the batch.
List three quality checks that can be carried out during germination.
- Moisture content analysis
- Acrospire growth
- Visual analysis
What does visual analysis involve?
Rubbing grains between your thumb and forefinger.
What does it indicate if the starchy endosperm looks like chalk on your fingers?
The green malt is correctly modified.
What happens if there is still cell wall material present when rubbing the grains?
It forms little balls, indicating the malt is under modified.
How long does barley typically spend in the germination vessel?
Four to six days.
What can over modification reduce?
Extract levels.
What issues can arise from the friable nature of over modified grain?
Grain can shatter, leading to dust losses and finer grist than required for wort separation.
What problems can under modified grain cause in the brewhouse?
Problems in filtration due to undegraded β-glucans.
What continues to happen during the first couple of hours of kilning?
The grain continues modification.
