Food safety

Question 1

Name me the causes of food spoilage.

Answer 1

In general, food spoilage is caused by
Microbial spoilage
Chemical spoilage
Physical spoilage
Effect of environment factors

Question 2

What are micro-organisms?

Answer 2

They are very small living organisms that can only be seen using a microscope.
The main micro-organisms responsible for the contamination of food are:
Bacteria
Moulds
Yeasts

Question 3

What is Bacteria?

Answer 3

Bacteria are tiny one-celled microbes.
They can be classified according to their shape:
Rod shaped (bacilli)
Example: Salmonella typhi, Clostridium botulinum
Round (cocci)
Example: Staphylococcus aureus

Question 4

What are the symptoms of food-borne diseases?

Answer 4

Typical symptoms of food-borne diseases include nausea, vomiting, diarrhoea and abdominal cramps. If severe case, pathogenic bacteria can cause death.

Question 5

Give me the causes of bacterial food poisoning.

Answer 5

Bacterial food poisoning can be caused by:
All species of salmonella, commonly found in contaminated eggs and raw poultry.
All species of vibrio, commonly
found in raw or undercooked
shellfish.
Escherichia coli (E.Coli)
commonly found in raw beef and
lamb

Question 6

How do moulds contaminate food?

Answer 6

Moulds grow from tiny cells call spores which are present in the atmosphere.
When mould spores settle on food, they infect it; the spores then grow quickly on the food that it soon becomes mouldy.

Question 7

What are the living conditions of moulds?

Answer 7

Moulds:
Are Multi-celled organisms.
Requires little moisture to survive & thus grow on relatively dry foods like bread/grains.
Can also grow in sauces & jams
Most moulds multiply between 25ºC & 30ºC.

Question 8

How do moulds reproduce?

Answer 8

Moulds reproduce by producing a large number of air-borne and heat-resistant of spores and will contaminate any food they come into contact with.
The toxic substance produce by mould is called mycotoxins

Question 9

How do yeasts reproduce?

Answer 9

Yeasts are one-celled organisms that are often spherical in shape.
When conditions are favourable, yeast cells multiply by budding, that is, a small bud grows on the side of the yeast cell. When the bud grows large enough, it splits off and forms a new cell.

Question 10

What are the living conditions of yeast?

Answer 10

Yeasts survive in moist condition.
They multiply in food with high sugar and low pH such as jam, fruit juice.
Yeast contamination can appear as slimy patches on the surface of the food such as ham.

Question 11

How does chemical spoilage occur?

Answer 11

Fats turn rancid in the presence of oxygen, heat and light
this chemical process breaks fats into glycerol and fatty acids and produce a distinct off-odour and an unpleasant taste.
Store high-fat food in a cool place, away from direct sunlight to reduce the occurrence of rancidity

Question 12

How does physical spoilage of fodo occur?

Answer 12

Occurs when food is physically damaged during harvesting, handling, distribution or storage (include flesh bruising, broken skin or damage caused by insects and rodents.
Weevils: infest opened rice/grains/flour
Pests: eats grains /outer skin of plants; introduce pathogenic bacteria in food as its waste contaminated with food

Question 13

What are the conditions that affect the rate of food spoilage?

Answer 13

Light
Oxygen
Warm temperature
The presence of moisture
An acidic environment

Question 14

How does light affect the rate of food spoilage?

Answer 14

Exposure to sunlight can result in the breakdown of light-sensitive food constituents such as colour pigments, fats, proteins and vitamins.
E.g. Vitamin B2 (riboflavin) is destroyed by UV light.

Question 15

How does oxygen affect the rate of food spoilage?

Answer 15

Encourage the growth of micro-organisms.
Accelerate the rancidity of fats and enzymatic browning.
E.g. cooking oils (usually unsaturated) are easily oxidised and turn rancid after being left outside for some time.

Question 16

How prescence of moisture affect the rate of food spoilage?

Answer 16

Moisture can encourage microbial growth in fresh meat, seafood, sauces and dips.

Question 17

How does an acidic environment affect teh rate of food spoilage?

Answer 17

An acidic environment
- Encourage yeast growth in fruit juices but prevent bacterial growth

Question 18

How does warm temperature affect the rate of food spoilage?

Answer 18

Warm temperature
Refer to optimum temperature for micro-organisms growth (in previous slides).
Bacteria grow best at 16oC to 48oC.
Yeast and moulds grow best at 20oC to 40oC.

Question 19

What are the four general guidelines for storing food?

Answer 19

1) Using appropriate containers
2)Keeping food in the right place
3)Checking the temperatures of areas for storing food
4)checking the keeping time of different food

Question 20

The First Guideline for storing food.

Answer 20

Use appropriate containers
Use polythene bag or air-tight container.
This limits the exposure of food to MCOGs, loss of moisture from food, and absorption of odours from other foods.

Question 21

The Second guideline for storing food.

Answer 21

Keep food in the right place
Store raw food below cooked food in the fridge. Juices from raw food will not drip onto the cooked food and contaminate it.

Question 22

The Third guideline for storing food.

Answer 22

Check the temperature of areas for storing food
Freezer compartment 🡪 at least 0oC and below
Chiller compartment 🡪 0oC to 4oC
Crisper compartment 🡪 0oC to 4oC

Question 23

The Fourth guideline for storing food.

Answer 23

Check the keeping time of different types of food
Store perishables like poultry, meat and seafood ASAP. Use them within 2 –3 days.
Write the date when you store the food so that it can be used before it is kept too long.

Question 24

How do you store meat,poultry and seafood?

Answer 24

Meat, poultry & seafood
Raw meat should be sealed in plastic bags or air-tighted containers & placed on shelves below cooked food.
Can be stored on the lower shelf of the chiller if not used within the day itself or in freezer
Large cuts of meat should be cut into smaller cuts & packed separately before freezing
Thaw only the amount of food that is required for cooking to avoid refreezing which lead to food spoilage

Question 25

How do you store Poultry?

Answer 25

Poultry
Remove the entrails of a plucked chicken and wash the inside thoroughly.
Chicken can be stores whole or cut into pieces.
Store in the freezer.

Question 26

How do you store fruit?

Answer 26

Fruit
Wash fruit to be eaten with the skin to remove insecticide.
Keep in the crisper compartment.

Question 27

How do you store vegetabes?

Answer 27

Vegetables
Wash away soil on leafy vegetables. Drain off water and then removed bruised leaves. Wrap them in kitchen paper towels. Keep in the crisper compartment.
Roots, tubers and bulb vegetables can be stored at room temperature; in an area that is dry and away from direct sunlight.
Bananas should be stored at room temperature as they will turn black if refrigerated.

Question 28

How do you store dairy products and eggs?

Answer 28

Dairy products & eggs
Milk- in the refrigerator once open; unopen UHT milk should be stored at room temperature.
Cheese, cream, butter & yoghurt cover and store in the chiller.
Eggs- kept @ room temperature if used within a few days otherwise stored them in chiller to prolong the shelf-life; the eggs should not be washed as the protective layer will be destroyed.

Question 29

How do you store dry foods?

Answer 29

Can be kept at room temperature & away from direct sunlight
Check grains and cereals occasionally to ensure that they are free of weevils.

Question 30

What are the practices to follow during cooking and serving?

Answer 30

Observe following practices:
When cooking or reheating food, the minimum internal temperature of food should be at least 75˚C
During serving, prepared food should be kept out of the temperature Danger Zone of 5˚C to 60˚C
Cooked food left at room temperature should be consumed within four hours