Effect of Temperature and pH

Question 1

What happens to enzyme activity when temperatures move away from their optimum?

Answer 1

Reaction rates reduce and enzymes can denature

Denaturation affects enzyme structure and function.

Question 2

How does temperature affect enzyme-catalysed reaction rates?

Answer 2

Rates increase with temperature until a maximum, then abruptly fall off

The increase is due to more energy available for reactions, while the drop is due to denaturation.

Question 3

What is the effect of small temperature variations on enzyme activity?

Answer 3

Changes of 10-20% in reaction rate

Small variations of 1-2°C can significantly impact enzyme activity.

Question 4

What happens to enzymes held at high temperatures for extended periods?

Answer 4

Greater decline in performance due to denaturation

Prolonged exposure to high temperatures can ‘cook’ the enzyme.

Question 5

How does pH affect enzymes compared to temperature?

Answer 5

Extreme pH values generally cause denaturation, but reaction rate drops more slowly than with temperature

Enzymes have different optimum pH levels.

Question 6

What is the typical optimum pH range for most brewing enzymes?

Answer 6

Between 4.5 and 6.0

This range varies among different enzymes.

Question 7

What does pH measure in a solution?

Answer 7

The acidity of the solution

pH is represented by -log of hydrogen ion concentration.

Question 8

What is the effect of an increased concentration of hydrogen ions on pH?

Answer 8

Lower pH and more acidic solution

More hydrogen ions increase acidity.

Question 9

What is the optimum temperature range for Pentosanases?

Answer 9

35-65°C

Inactivation temperature is 70°C.

Question 10

What is the optimum pH for Endo β-(1,4) glucanase?

Answer 10

4.5-4.8

This enzyme acts on β-Glucans.

Question 11

What is the inactivation temperature for α-Amylase?

Answer 11

75-80°C

This enzyme has an optimum pH of 5.3-5.8.

Question 12

How does enzyme:substrate ratio affect reaction rates?

Answer 12

Higher enzyme concentration increases reaction rate

If substrate concentration is increased, the rate rises until a maximum is reached.

Question 13

What is an example of enzyme inhibition in mashing?

Answer 13

α-Amylase being inhibited by phytic acid

Inhibition can also occur by products of the reactions they catalyse.

Question 14

What are the functions of starch degrading enzymes?

Answer 14

They break down starch into simpler sugars

Specific examples include α-Amylase and β-Amylase.