Protein Degrading Enzymes Flashcards
(17 cards)
What is the role of proteases in yeast nutrition?
Proteases help provide the FAN for yeast but can reduce foam stability and beer body if overactive.
FAN stands for Free Amino Nitrogen, which is essential for yeast growth.
What can happen if there is too much FAN in beer?
Too much FAN can increase beer colour and flavour and cause it to stale more rapidly.
Define a protease.
A protease, also known as a peptidase or proteinase, is an enzyme that catalyses proteolysis.
What do endoproteases do?
Endoproteases catalyse the hydrolysis of bonds at specific points in the protein molecule but not at the ends of the amino acid chains.
What is the function of exoproteases?
Exoproteases catalyse the hydrolysis of bonds in protein molecules at the ends of the amino acid chains.
How do endoproteases and exoproteases differ in concentration?
The concentration of endoproteases is lower than that of exoproteases, limiting protein breakdown in the mash.
What do carboxypeptidases do?
Carboxypeptidases catalyse the hydrolysis of peptide bonds at the carboxyl end of the amino acid chain.
What is the function of aminopeptidases?
Aminopeptidases catalyse the hydrolysis of peptide bonds at the amino end of the amino acid chain.
What role do aminopeptidases and carboxypeptidases play in yeast nutrition?
They produce the majority of the soluble nitrogen required for yeast nutrition.
What increases the activity of aminopeptidases and carboxypeptidases?
The availability of sulphate ions.
What is the optimum temperature for protease enzymes?
Around 50°C.
Why are protease enzymes considered heat sensitive?
Many are denatured during kilning, leading to insufficient supply in malt for hydrolysing proteins.
What is the importance of degrading barley proteins during malting?
It ensures sufficient breakdown of proteins for effective hydrolysis in the mash.
What is β-glucan solubilase?
β-glucan solubilase is a carboxypeptidase that catalyses hydrolysis of protein cross-links between β-glucan molecules.
What is the optimum temperature for β-glucan solubilase?
60°C.
What problem can arise from the activity of β-glucan solubilase during mashing?
It can release long chains of glucose residues that increase wort viscosity.
Why is it essential to break down β-glucans during the malting process?
To prevent viscosity issues in the wort and ensure effective enzymatic activity.
