Unit 1 lesson 4 part 2 Flashcards
What are the main enzymes involved in modification during germination?
- β-glucan solubilase
- Endo-β-glucanases
- Pentosanases
- Endo and exoproteases
- α-amylase
- β-amylase
- Limit dextrinase
These enzymes play key roles in breaking down cell walls, proteins, and starch granules.
When are β-glucan solubilase, β-amylase, and carboxypeptidase first activated during germination?
Day 1
These enzymes are crucial for the initial breakdown of the endosperm.
What role does phytase play during germination?
Produces phosphate from phytic acid for cellular functions.
Phytase is found in the embryo and aleurone layer of barley.
Fill in the blank: The _______ layer must be broken down by enzymes like xylanases before β-glucanases can degrade the cell walls.
Pentosan
The pentosan layer contains organic acids and is porous.
True or False: Higher germination temperatures always yield higher levels of amylase enzymes.
False
Cooler germination temperatures yield higher amylase levels.
What is the result of the combined action of α-amylase and β-amylase on starch?
- Production of short chain sugars
- Production of longer chain dextrins
Both enzymes contribute to the breakdown of starch for embryo growth.
What factors influence the level of α- and β-amylases during germination?
- Barley variety
- Kernel size
- Moisture content
- Germination temperature
These factors can significantly affect enzyme production.
What are the two parameters that can be adjusted to control germination?
- Bed temperature
- Moisture in the bed
Both parameters are critical for effective germination and enzyme activity.
During which days of germination is α-amylase first activated?
Days 2-4
This enzyme is crucial for starch breakdown during germination.
What is the purpose of the acrospire growth test?
To determine the extent of modification during germination.
The length of the acrospires indicates the degree of germination.
What happens if there is too much protein breakdown during germination?
Destroys proteins needed for beer foam.
A balance in proteolysis is crucial for quality.
What is the role of lipase during germination?
Breaks down lipids to produce fatty acids for energy.
Fatty acids are vital for the developing barley embryo.
What is the effect of excessive fertilizer use on the protein matrix density?
Increases density, making grains harder and more resistant to enzymes.
This can negatively affect the modification process.
What is the significance of controlling air-on and air-off temperatures?
Maintains optimal conditions for germination and enzyme activity.
This helps prevent overheating and ensures effective modification.
What is the term used for the batch at the end of germination?
Green malt
What does the starchy endosperm of correctly modified green malt feel like?
Chalky on fingers
How long does barley typically spend in the germination vessel?
Four to six days
What can over modification of grain lead to?
Reduced extract levels and milling problems
How long does kilning typically take?
24 to 48 hours
What is one reason for kilning green malt?
To reduce moisture content
True or False: Higher kilning temperatures result in higher levels of SMM.
False
What is the industry standard for NDMA levels in malt?
Below 1 μg/kg
What type of kilns are modern designs often compared to?
Circular germination vessels
What is the typical bed depth during kilning?
0.75 m
