Food Spoilage And Contamination Flashcards
What are the four ways food can spoil?
Moulds
Yeast
Bacteria
Enzymic browning
When do the enzymes in food react with oxygen?
When they are bruised or cut open
What causes overripening in fruits?
Enzymes
What foods do yeasts mostly grow on?
Acidic and sweet foods
What does yeast produce when it ferments the sugar in food?
Alcohol and carbon dioxide
What conditions do moulds grow in?
Moist
Warm (they can grow in cold conditions given time)
Why is it important to sterilise jam hars before use?
The boiling process destroys mould in jam, but if they aren’t sterilised mould spores can grow in the jam
When should you put the lid on homemade jam and why?
Either as soon as the jam is made or once the jam has completely cooled so condensation doesn’t form on the lid and dilute the sugar on the surface, allowing mould to grow
Why can you just scrape mould off food?
Moulds grow throughout the food to extract nutrients from it
What are yeasts?
Tiny single celled fungi
Microorganisms
What are moulds?
Tiny fungi that produce spores
Microorganisms
What are enzymes?
Biological catalysts
What is pasteurisation?
Heat treatment that kills most microorganisms in food
What is sterilisation?
Something is heated to kill bacteria yeasts and moulds
Whatvare mould spores?
Spores produced by mould that help it spread
How does yeasts spoil food?
They change the texture taste smell or colour of the food by fermenting the sugar
How is yeast used in food production?
It is used as a raising agent and in the brewery industry
How is mould used in food production?
To improve the colour and flavour of cheese
Ripen the surface of sausages and improve their smell and shelf life
How is bacteria used in food production?
Making cheese and yogurt
What are the raw ingredients for making cheese?
Milk
Rennet
Salt
A starter culture of bacteria
Why is milk used for cheese making pasteurised?
To kill harmful bacteria
Explain the steps of cheese making
pasteurised milk is warmed
The starter bacteria culture is added to sour it
Rennet is added to increase the rate of curdling (separate into curds and whey)
These are then cut to release the way and drain it
The curd is heated, stirred, and milled to form small pieces.
Salt is added to help flavour and preserve the cheese
The curd is pressed into moulds to make blocks of cheese
It then goes into cool storage
Explain the yoghurt making process
Harmless bacteria are added to warm previously boiled milk and allowed to multiply in warm conditions
The lactose turns into lactic acid
The lactic acid denatures and coagulates to thicken the milk into yoghurt
Why is it important to sterilise equipment before yoghurt making?
So the yoghurt doesn’t become contaminated with pathogenic or Spoilage bacteria
What is the effect of adding bacteria to milk at the beginning of stages of making cheese?
The bacteria culture converts the sugar in the milk into lactic acid and begins the cheese making process
What is Rennet?
It contains an enzyme called rennin, which makes milk separate into curds and whey
What is milling curd?
The process of breaking blocks of curd into smaller pieces
What raw foods carries food poisoning bacteria?
Meat
Raw eggs
Shellfish
Rice
Vegetables
How do you prevent bacteria contamination from work surfaces and equipment?
Always clean surfaces and equipment before and after use
Surfaces and equipment that have touched raw meat should be thoroughly cleaned
Separate equipment should be used for raw and cooked foods
Colour code or lable equipment
Use clean tea towels every day
How can you prevent food from being contaminated by a food handler?
Use tongs to pick up food
Use a clean teaspoon and don’t double dip when tasting
Don’t touch the part of utensil that come into contact with food
How can you prevent food from being contaminated by pests?
Keep windows and doors shut if possible to keep pests out
Cover all rubbish bins
Keep all work surfaces clean
Wash up straight away
Clean kitchen after each cooking session
Don’t leave food out overnight
Empty and clean bins regularly
Don’t let domestic pets in food preparation areas
How can you prevent food contamination from bins?
Use bins with lids
Use thick bin bags
Empty bins as soon as they are full
Use a foot operated bin
Wash the bin regularly
What are some at risk groups of food poisoning?
Babies and young children
Pregnant women
Elderly people
Those with reduced immunity
What can cause food poisonings?
Contaminated water
Undercooked food
Eating food that is touched by someone infected or that has a septic cut
Cross contamination of pathogenic bacteria
What are the general symptoms of food poisoning?
Vomiting
Diarrhoea
Nausea
Stomach pains
When does food poisoning start?
Withing two hours of eating the food or up to many days after
What is the most comman food poisoning int he UK?
Campylobacter
What causes campylobacter?
Contaminated poultry
Undercooked chicken
Cross contamination from raw chicken
Transfer from domestic pets and other animal
Why should you not wash meat before cooking?
It spreads bacteria around the kitchen
Where can e. coli bacteria be found?
Intestines of people and animals
Faecle contamination
Where can salmonella bacteria be found?
Intestines of farm animals and can contaminate meat poultry eggs and milk.
Vegetable fruit and shellfish due to contact with manure or sewage water
How do you reduce the risk of salmonella food poisoning?
Raw food should be kept away from ready to eat foods in the fridge
Vegetables should be washed before preparation
Raw foods should be cooked thoroughly
Where are listeria bacteria found?
Soil
Decaying vegetation
Water
Unpasteurised milk and cheese
Food manufacturing environments
What is unusual about listeria bacteria?
It can multiply to dangerous levels at fridge temperatures
Where can staphylococcus Aureas bacteria be found?
Human skin and mucus linings
Unpasteurised milk
Meat and meat products
An infected person contaminating ready to eat food
What does at risk mean in relation to food poisoning?
People that get more serious outcomes of food poisoning
When should ypu wash your hands.
Before you start any food preparation
After touching your hair or face
After using the toilet
After blowing your nose
After cleaning or putting rubbish in the bin
After handling raw meat seafood vegetables or eggs
After eating or drinking
What are some hygiene rules for the kitchen?
Don’t cough or sneeze near food
Don’t touch your head
Don’t brush your hair in the food room or with your apron on
Long hair should be tied back or covered
Wounds should be covered with a coloured waterproof plaster
Wear a clean apron
Don’t prepare food if you are unwell
What should be used to clean work surfaces?
Hot soapy water and an antibacterial spray
How can you prevent the spread of bacteria at a barbecue?
Use separate plates and utensils for raw and cooked food
Why do beef burgers have to be cooked all the way through?
The meat is minced, so bacteria is mixed to the centre of the burger
How can you prevent food poisoning when serving food?
Serve food as soon as its cooked
Keep it hot at 63°C or above
Use clean tongs
Plates should be the appropriate temperature
Don’t put hot food in the fridge
What can you use a temperature probes for?
Checking food is fully defrosted before cooking
Checking cooked food has reached a safe temperature
Checking if reheated food is a safe temperature
Why should food like chicken be fully defrosted before cooking?
If it is not fully defrosted, it will take longer to cook, which gives the bacteria more time in the temperature danger zone, so more time to multiply. It also means chicken is more likely to be undercooked.
What are the rules for reheating food?
Keep food in the fridge
Keep food covered and handle as little as possible
Divide food into smaller quantities to reduce reheating time
Don’t reheating food more than once
Throw away reheated food that isn’t eaten
