Enzymes

Question 1

What are enzymes?

Answer 1

Enzymes are catalysts that accelerate the rate of metabolic reactions.

Question 2

What are the characteristics of an enzyme?

Answer 2

• Operates as the “lock and key” model. With an exception that enzymes can catalyze multiple substrate., therefore the induced fit model is more commonly accepted.
• Most enzymes can be irreversibly or reversibly denatured.
• Enzymes are classified according to the reactions catalyzed.

Question 3

What are the 6 classes of enzyme?

Answer 3

Class I: Oxidoreductase
Class II: Transferase
Class III: Hydrolase
Class IV: Lyase
Class V: Isomerase
Class VI: Ligase

Question 4

What are some use of enzymes in the food industry?

Answer 4

• Food processing
• Grain processing
• Feed enzymes (Improve digestibility of animal feeds)

Question 5

Give examples of enzymes used in producing fruit juices and their purposes.

Answer 5

Glucose oxidase: Catalyze glucose oxidation and enhance the storability
Catalase: Removes air present in the headspace of bottled drink
Pectinase: Break down pectin to increase clarity and yield
Amylase: Juice clarification.
Arabanase: Breaks down araban to prevent hazing
Limonoate dehydrogenase: Prevent the formation of limonin the remove bitterness.

Question 6

Give an example of enzyme used in milk production.

Answer 6

Lactase (Beta-galactosidase): Split milk-sugar lactose into glucose and galactose to produced lactose free milk.

Question 7

What is the purpose of rennet in cheese making?

Answer 7

Rennet is an enzyme added to clot the proteins in milk to form curds by cleaving the peptide bonds of casein.

Question 8

What are the general steps of cheese making?

Answer 8

• Coagulating the casein protein in milk
• Separating the milk into solid curds and liquid whey
• Liquid whey is drained away, and the curds salted and shaped
• Curd is left to ripen in a controlled environment.

Question 9

What are some ways to produce rennet?

Answer 9

Calf rennet: Sourced from calves, animals must be killed and there’s a risk for disease
Fungal rennet: Sourced from fungus, cheap, large amounts, and acceptable for vegetarians. Taste disadvantage
GM Yeast rennet (FPC): Sourced from yeast, no animals involved, good for vegetarians and same as animal rennet, disadvantage of public concern and acceptability of GM.