Year 6 - Sc Note

1. FOOD SPOILAGE

2. FOOD SPOILAGE
All food turns bad or spoilt after a certain period of time.
Characteristics of spoilt food:
1. Unpleasant smell
2. Unpleasant taste
3. Change colour
4. Change texture
5. Mouldy

3. FOOD SPOILAGE
FOOD CHARACTERISTIC
Bread and cakes •Turns mouldy with black, green or white dots or
hairy patches
•Has unpleasant smell and taste
•Become slimy
Vegetables •Turn yellowish
•Become soft and withered
•Become slimy and watery
Fruits •Become bruised
•Turns mouldy
•Has unpleasant smell and taste

4. FOOD SPOILAGE
FOOD CHARCTERISTIC
Fish and meat •Has unpleasant smell
•Flesh becomes sunken when pressed
•Has pale gills and sunken eyes in fish
Milk •Smells and taste sour
•Becomes curdled and foamy
•Its has swells (bulges)
Canned food •Tin can swells (bulges)
•Food in it smells bad

5. FOOD SPOILAGE
Food become rotten or decayed food
Why? Due to the microorganism mainly bacteria and fungi
Microorganism live and feed on the food. It breaks the food
down into simpler substances. This process called decaying.
When the food is decaying, it will smell and taste unpleasant
and cause food poisoning when we eat.
Microorganism need air, water, nutrients (food), moderate
temperature and suitable acidity to grow.

6. FOOD PRESERVATION

7. FOOD PRESERVATION
Involves treating food so it can be stored without spoiling for
along time.
Prevents or slow down the growth of microorganism on
food.
Killing the microorganism or making the condition
unsuitable for them to growth and survival.

8. WASTE

9. TYPES OF WASTE
Some waste can be decayed and some cannot be decayed
The waste can be decayed by the microorganism is called
biodegradable waste.
The waste cannot be decayed by he microorganism is called
non biodegradable waste
Mostly biodegradable waste originated from living thing. For
examples:
1. Discarded food, sewage, animal waste, paper and wood
2. Certain types of plastics known as biodegradable plastics and
detergents known as biodegradable detergent.
3. Effluent from factory that produce food or processes
agricultural product such as palm oil and rubber

10. Biodegradable Waste
Decaying and decomposition is a process of breaking a
material down into simpler substances by microorganism.
The biodegradable waste changes like the following:
1. Change in appearance : It may change colour, become softer,
become liquid or gas.
2. Reduction in size and volume : For example, a huge heap of
dried leaves will be come small heap
It can also be useful. The biodegradable waste can be used to
make compost, nutrient-rich substance used as fertilisers.

11. Advantages and disadvantages of
waste decay
Advantages
Allows nutrient in waste to be returned to the soil and be
reused.
Helps to reduce the volume of waste.
Disadvantages
Contribute to global warming
Methane is produced by the global warming. Methane is a
flammable gas. It will cause the landfill catch the fire easily
especially during the hot and dry season.
Rubbish and sewage treatment plants give out the bad smell.

12. Non Biodegradable Waste
Non biodegradable waste remain in the environment for a
very long time.
It cannot be decayed easily.
For example : The plastic bag takes about 10 to 20 years to
decay.
We should reduce the waste by reused and recycle them.