Food Spoilage Flashcards
What do enzymes cause fruit to do e.g makes bananas ok to eat
Ripen
What do fruits contain that cause them to ripen
Enzymes
3 sensory properties that enzymes effect when they ripen fruit
Texture
Sweetness
Colour
2 methods that control the activity of enzymes (e.g stopping enzymic browning where the fruit is oxidated and turns brown)
Adding acid e.g dipping fruit slices in lemon juice- enzymes work best at optimum ph so when too acidic it stops the enzymic browning
Blanching- destroys ripening enzymes
What happens when fruit is sliced and exposed to air
Enzymic browning
Oxygen in air turns fruit brown and enzymes speed up the process
What temperature is the danger zone
5- 63 degrees
What temperature is the freezing zone
Below - 18 degrees
What temperature is the chilling (fridge) zone
0-5 degrees
Where in the fridge should raw meat be placed and why
Bottom shelf
Stop any juices/ blood dripping and contaminating other foods with harmful bacteria like salmonella that can cause food poisoning
What happens to bacteria between 5 and 63 degrees (danger zone)
Grows and multiplies rapidly
Optimum temperature for bacterial growth
37 degrees
(Included in danger zone)
Why should hot food be held above 63 degrees
Any lower is in the danger zone where bacteria grows and multiplies rapidly
Therefore avoids bacteria growing on food which could cause food poisoning
True or false, freezing kills bacteria
False
It becomes dormant (stops growing) but becomes active again when the food is defrosted
What does chilling do to bacteria (e.g putting food in the fridge)
Slows the growth but doesn’t stop it
What is meant by ambient foods
Foods kept at room temperature
Use by vs best before date
Use by is about safety
Best before is about quality
Use by date meaning
Given as a safety warning
Date that a high risk food must be consumed by (after this point you may get food poisoning)
What type of foods contain a use by date
Short shelf life
E.g high risk foods
What is meant by best before date
Given as warning about quality
After the date the food is still safe to eat but might not be as nice e.g biscuits might go soft
What type of foods contain a best before date
Long shelf life
E.g tinned foods
Would a can of baked beans have a use by date or a best before date and why
Best before
It is long shelf life
The food will be safe to eat it may just start to taste a bit off
What must you do to a probe before and after use
Sterilise it
General Symptoms of food poisoning
Diarrhoea, vomiting, stomach cramps, fever
4 main types of bacteria to know
Salmonella
Campylobacter
E.Coli
Staphylococcus aureus
Why it’s important to fully defrost food (e.g frozen chicken) before cooking
Otherwise the food might take longer to cook than the packaging says so you end up undercooking it so the harmful bacteria isn’t killed but remains in the food causing food poisoning
How does jam making preserve food
Fruit and sugar are boiled then sealed in jar
High temperature when boiled destroys bacteria
Sealed jar means oxygen can’t get in preventing the food from spoiling
Sugar prevents microorganism growth
Minimum core temperature food should be cooked to
75 degrees
Minimum temperature hot food (e.g in a buffet) should be held at
63 degrees
Hot buffet food should be kept for no more than how many hours
2 hours
Pasteurisation meaning
Heat heated up to 72 degrees for 15 seconds then rapidly cooled
(At high temperature harmful bacteria is killed so prevents food poisoning when milk is consumed)
During pasteurisation, milk is heated to how many degrees
72 degrees
During pasteurisation, milk is heated to 72 degrees for how many seconds
15 seconds
Why pasteurisation makes milk safe to drink
Heated to 72 degrees and at high temperature bacteria is killed preventing food poisoning
Campylobacter is found in what 2 things
Raw poultry
Untreated milk
(Think c for cow as cows produce milk and meat)
E.coli is found in what 2 things
Unwashed vegetable leaves
Raw beef
Staphylococcus aureus is found in what
High risk foods handled by someone carrying the bacteria
(Think s for someone)
Salmonella is found in what 2 things
Raw poultry
Eggs
What is enzymic browning
Enzymes speed up the reaction with oxygen in the air turning fruits and vegetables brown
5 ideal conditions for bacteria to grow and multiply
Food
Moisture
Warmth
Time
PH
2 methods to help prevent enzymic browning
Add acid
Blanching
(Slows down oxidation)
How blanching helps prevent enzymic browning
Destroys ripening enzymes
How preservatives prevent food spoilage e.g sugar in jam, vinegar, salt and lemon juice
Prevent growth of microorganisms
(Due to being too acidic etc)
How preservatives prevent food spoilage e.g sugar in jam, vinegar, salt and lemon juice
Prevent growth of microorganisms
(Due to being too acidic etc)
Examples of high risk foods (short shelf life ready to eat foods)
Cooked meat
Dairy products
Gravies/ sauces
Cooked rice
Ready made meals
5 methods of preserving food by keeping it in a cool and dry place to prevent growth of microorganisms
Freeze drying
Canning/ bottling
Vacuum packing
Pickling
Jam making
