causes of food spoilage and contamination

Question 1

Environmental factors

Answer 1

oxygen
light
heat
water
infestation

Question 2

Oxygen

Question 3

Light

Question 4

Heat

Question 5

Water

Question 6

Infestation

Answer 6

worms, bugs, weevils, fruit flies, moths cause extensive damage to food and reduce its nutritional value and make it unfit for human consumption.

Question 7

_________ activity on food

Answer 7

enzymatic activity on food
enzymes are organic catalyst present in living cells. the life of every living cell depends upon the chemical reactions activated by these enzymes.
enzymes are sensitive to heat and are easily destroyed by heat and all enzymes are inactivated by temperatures above 80°C.
there are 3 types
ripening
browning
rotting

Question 8

Ripening

Answer 8

enzymes cause food to ripen, then become over-ripe and eventually decay.
starch changes to sugar, colour changes and texture softens.

Question 9

Browning

Answer 9

when certain foods are cut and the surface exposed to air, enzymes cause them to turn brown.
e.g. apples

Question 10

Enzymatic rotting

Answer 10

enzymes in fish cause deterioration even at low temperatures.

Question 11

Microbial contamination of food

Answer 11

growth of microbes in food
mould
yeast
bacteria

Question 12

Mould

Answer 12

contain spores which can spread through the air and start new mould plants.

Question 13

Yeast

Answer 13

during yeast fermentation, the sugars present in the food are broken up to form alcohol and carbon dioxide.
perishable foods can be spoiled by yeast

Question 14

Bacteria

Answer 14

bacteria are unicellular organism and are much smaller in size than either yeasts or moulds. They occur in different sizes and shapes.
they also vary in their requirement for food, moisture, acidity, temperature and oxygen.
bacteria can grow and develop rapidly between 20°C and 53°C.
there are 3 classifications depending on the temperature they grow at.
1. A higher temperature than 45°C are known as thermopile.
2. Temperatures between 20-25°C are called Mesophiles.
3. Temperature less than 20°C are called psychrophites.

Question 15

Causes of food spoilage and contamination

Answer 15

• environmental factors, such as oxygen, light, heat, water, infestation
• enzymatic activity on food
• microbial contamination of food, such as mould, yeast, bacteria

Question 16

Definition of food spoilage

Answer 16

food spoilage refers to undesirable changes occurring in food