Gibberellic Acid and the Enzymes of Modification

Question 1

What is the role of gibberellic acid (GA) in the malting process?

Answer 1

GA acts as a chemical message that stimulates enzyme production in the aleurone layer

GA is produced by the embryo from a stored precursor as the embryo begins to grow and use up its energy stores.

Question 2

What happens to the sugar level in the embryo as it begins to grow?

Answer 2

The sugar level in the embryo falls, prompting the production of GA

This decrease in sugar levels signals the embryo to produce GA, which is essential for enzyme activation.

Question 3

What is the first root that appears during germination called?

Answer 3

Chit

The chit is an indication that germination has commenced, typically appearing after 24 hours.

Question 4

What is the moisture content increase during steeping?

Answer 4

From ~ 12% to ~ 45%

Steeping is a critical process that prepares the grain for germination by increasing moisture content.

Question 5

List the enzymes synthesized de novo in response to GA.

Answer 5

• α-Amylase – starch
• Limit dextrinase – starch
• Endoproteases – protein

These enzymes are crucial for breaking down starches and proteins during the malting process.

Question 6

List the enzymes that are already present in the grain and activated during malting.

Answer 6

• Endo β-(1,3)(1,4) glucanase – β-glucans
• Endo β-(1,3) glucanase – β-glucans
• Pentosanase – pentosans
• β-Amylase – starch
• Carboxypeptidases and other exoproteases – polypeptides
• Phytase – phosphate containing compounds
• Lipase – lipids

These enzymes are activated to facilitate the breakdown of various components in the grain.

Question 7

True or False: Germination starts at kernel moistures > 30%.

Answer 7

True

This indicates that sufficient moisture is necessary for the germination process to begin.