Spoilage Of Fish

Question 1

Why is the storage of fish so important?

Answer 1

Fish is an extremely perishable food, so it must be stored on ice and used or processed as quickly as possible

Question 2

How many types of spoilage affect fish?

Answer 2

Three

Question 3

Name the three types of spoilage that affect fish.

Answer 3

Oxidative rancidity

Enzymes

bacteria

Question 4

Write a note on how oxidative rancidity affects fish.

2

Answer 4

Oils in oily fish react with oxygen in the air

Oxygen combines with the carbons in double bonds along the unsaturated fatty acid chain, causing the fish to become rancid

Question 5

What in oily fish reacts with oxygen to cause oxidative rancidity?

Answer 5

The oils in oily fish

Question 6

Explain how oxidative rancidity causes the spoilage of fish.

Answer 6

Oxygen combines with the carbons in double bonds along the unsaturated fatty acid chain, causing the fish to become rancid

Question 7

Write a note on how enzymes cause the spoilage of fish.

2

Answer 7

Naturally present enzymes in fish cause its flesh to deteriorate, even at low temperatures

This can be slowed by placing fish on ice or in the fridge

Question 8

What is naturally present in fish which causes spoilage?

Answer 8

Enzymes

Question 9

What can be done to slow down enzymic spoilage?

Answer 9

This can be slowed by placing fish on ice or in the fridge

Question 10

Write a note on how bacteria cause the spoilage of fish.

3

Answer 10

When fish are caught they struggle frantically, using up the glycogen in their muscles and liver

This results in little glycogen being left to convert to lactic acid to preserve the fish, which in turn causes rapid deterioration by bacterial action

This produces a strong-smelling nitrogen compound called trimethylamine

Question 11

What is used up when fish are caught and struggle frantically?

Answer 11

Glycogen in fish muscles and liver

Question 12

What should glycogen be converted into when fish is killed?

Answer 12

Glycogen should convert to lactic acid

Question 13

What is the function of lactic acid?

Answer 13

It helps preserve fish

Question 14

Why does deterioration occur if lactic acid is meant to preserve fish?
(2)

Answer 14

Due to the fact that most of the glycogen in fish is used up when fish are caught

This means there isn’t enough glycogen to convert into lactic acid and preserve the fish

Question 15

What does the spoilage of fish by bacterial action do?

Answer 15

This produces a strong-smelling nitrogen compound called trimethylamine

Question 16

Name the compound given off by fish which has undergone bacterial spoilage.

Answer 16

Trimethylamine