Section Three - Food Spoilage

Question 1

What are the five conditions needed for bacteria, mould and yeasts to grow quickly?

Answer 1

1)A warm temperature
2)Plenty of moisture
3)Plenty of food
4)The right Ph
5)Enough time
Changing any one of the conditions will slow or stop this growth

Question 2

What are high risk foods? Examples?

Answer 2

They are ready to eat foods that can grow bacteria if not stored correctly
They moist and high in protein, examples are cooked meat, dairy products, gravies, stocks and sauces, shellfish and cooked rice

Question 3

How do enzymes in fruit cause them to ripen?

Answer 3

Enzymes in fruit cause them to ripen which affects the sweetness, colour and texture of the fruit
E.g. unripe bananas are green and firm- enzymes break down starch inside them which makes the banana softer and sweeter

Question 4

How do enzymes in fruit cause them to brown?

Answer 4

When you slice fruits the oxygen will turn the fruit brown, enzymes in the fruit speed up this process.
Leaving some fruits too long will cause them to overripen

Question 5

How can you slow or stop an enzyme from working?

Answer 5

Adding an acid- enzymes work best at a certain pH, dipping fruit into lemon juice the acidic conditions will stop enzymic browning
Blanching- is used to prepare vegetables for freezing. Freezing doesn’t stop ripening enzymes completely but slows them down. Blanching kills the ripening enzymes.

Question 6

How do mould and yeast spoil food too?

Answer 6

They are microorganisms this means in the right conditions they can grow and spread quickly.
They can change the look, smell and taste of food
Waste products from moulds can cause food poisoning
It can be prevented by storing food 8n the correct conditions

Question 7

What temperature should food be when cooking or reheating? Why?

Answer 7

Cooking food above 75 degrees c kills bacteria
Its important to reheat food properly and only once
Reheat the food above 75 for more than 3 minuets

Question 8

What is the danger zone (temperature)?

Answer 8

Bacteria grow and multiply from 5 to 63 degrees, called the danger zone
Optimum for bacterial growth is 37 degrees

Question 9

What temperature should chilling be done at?

Answer 9

Keeping food between 0 and 5 degrees slows the growth of bacteria
This extends the shelf life of the food
Chilling foods doesn’t change looks and tastes the same but it may have a harder texture.

Question 10

What temperature is freezing done at?

Answer 10

Freezing food below -18 degrees stops bacteria growth

It greatly extends the shelf life, it doesn’t kill bacteria they become active again when it defrosts

Question 11

How should fridges be used correctly?

Answer 11

0 to 5 degrees
Keep food covered or stored in containers to prevent contaminating other foods
Don’t let the blood and juices of raw meat drip onto other foods always keep this kind of stuff on the bottom shelf

Question 12

How should freezers be used correctly?

Answer 12

Should be set at about -18degrees c
Clear labels with dates
Defrost meats thoroughly in a fridge
It takes longer to cook food from frozen than chilled

Question 13

What is freeze drying?

Answer 13

Food is frozen and dehydrated to remove moisture from the food

Question 14

What is canning/bottling?

Answer 14

Food is sealed in a can or jar and heated to kill microorganisms

Question 15

Vacuum packing

Answer 15

Food is put in plastic packing and the air is sucked out some microorganisms cant live without oxygen

Question 16

Pickling

Answer 16

Food is plunged in brine or vinegar making it too acidic for bacteria

Question 17

What is jam making?

Answer 17

Fruit is broiled with sugar and pectin and sealed In a glass jar. The high sugar content prevents microorganisms growth

Question 18

What is the use by date?

Answer 18

The use by date is shown on products with a short shelf life e.g. high risk foods
Its given as a safety warning, if you use the food after this date it isn’t safe

Question 19

What is the best before date?

Answer 19

It is on products with a longer shelf life

Its given as a warning about quality, if you eat food after this day it might not be as nice as expected

Question 20

What is cross contamination and how does it occur?

Answer 20

Its easy to pass bacteria from raw food to work surfaces, equipment and hands
It can happen from a variety of different sources:
-other contaminated food- raw meat juices can drip onto other food
-utensils, equipment and work surfaces- using unclean equipment, dirty cloths on work surfaces, chopping board for both meat and veg
-people- poor personal hygiene sneezing, coughing, hands
-Pests- walking over food, laying eggs or droppings. Waste attracts pests

Question 21

What safety and hygiene procedures should you take when preparing food?

Answer 21

• Wash vegetables thoroughly
• Use clean equipment and a antibacterial spray on work surfaces
• Follow personal hygiene procedure- wash hands, clean apron, hair net
• Separate raw and cooked foods and use different chopping boards for meat and veg
• defrost food fully, in the bottom of a fridge and away from other foods

Question 22

What safety and hygiene procedures should you take when cooking food?

Answer 22

• Cook food at the right temperatures and for the correct times
• Make sure food is cooked all the way through
• test the temperature inside using a temperature probe

Question 23

What safety and hygiene procedures should you take when serving food?

Answer 23

• serving hot food straight away or keep it above 63 degrees for no longer than 2 hours
• if you’re serving food cold or storing it, cool id own with 90mins
• keep food covered
• Try to avoid food waste and check waste bins are not overfilled

Question 24

What causes food poisoning, what are the symptoms?

Answer 24

Symptoms include sickness, diarrhoea, stomach cramps and fever
In extreme cases it can cause death
You get it by eating contaminated food containing pathogenic bacteria it can take a few hours to several days to experience any symptoms

Question 25

Where is salmonella found, what are the symptoms of infection and the onset time of infection?

Answer 25

Found in raw poultry, untreated milk and eggs
Symptoms include diarrhoea, stomach cramps and vomiting
Onset time 6-72hrs

Question 26

Where is salmonella found, what are the symptoms of infection and the onset time of infection?

Answer 26

Mainly found in raw or undercooked poultry, but also in raw meat and untreated milk/water
Symptoms include bloody diarrhoea, stomach cramps and fever
Onset time is 2-5days

Question 27

Where is E.coli O157 found, what are the symptoms of infection and the onset time of infection?

Answer 27

It lives in the intestines of animals and can contaminate raw beef, untreated milk/water, unwashed veg and salad leaves.
Most types are harmless but E.coli O157 can cause kidney damage and death
Onset time 1-3 days

Question 28

Where is Staphylococcus aureus found, what are the symptoms of infection and the onset time of infection?

Answer 28

They live on the skin and hair and in the noses of animals and people
Poor personal hygiene can contaminate food
Symptoms include diarrhoea, stomach cramps, vomiting and mild fever
Onset time is 1-6hrs

Question 29

How are milk and egg treated to control bacteria?

Answer 29

All milk is pasteurised. Milk is heated to 72 degrees for 15 seconds before chilling to kill of any bacteria
Chicken are vaccinated against salmonella so it doesn’t contaminate their eggs