Section 3- Food safety Flashcards
What are examples of microorganisms?
bacteria, moulds and yeasts
What are the 5 conditions microorganisms need to grow and multiply?
warm temperature, moisture, food, pH, time
What conditions could you change to slow or stop the growth of microorganisms?
- use a fridge to change temperature
- pickle the food in vinegar to change the pH
- add salt (salt absorbs water which removes the moisture from the food)
What are high risk foods?
ready-to-eat foods that if not stored correctly could grow harmful bacteria
What are some examples of high risk foods?
cooked meats, fish and poultry, dairy products, gravies, stocks, shellfish
Why isnt chicken classed as a high risk food?
chicken might have lots of bacteria but its not classed as a high risk food because you dont eat it raw
- once its cooked and “ready to eat” it can be described as high risk
What is an examples of how you can identify when a high risk food is spoiling?
- meat going slimy, milk smelling sour or cheese going mouldy
How can you check there are no visible signs of spoilage when buying food?
- fresh meat should be brightly coloured, firm and have a fresh smell
- fresh fish should have shiny skin, red gills, clear eyes and smell clean or slightly salty
What are enzymes?
- special proteins that act as biological catalysts
- they speed up chemical reactions
How can you see the effects of enzymes during ripening?
- enzymes in fruit cause them to ripen which affects the sweetness, colour and texture of the fruit
How can you see the effects of enzymes during browning?
- when you slice fruits the oxygen in the air will turn the fruit brown
- enzymes in the fruit speed up this process
How can you have control over the activity of enzymes?
adding an acid- enzymes work better at a certain pH, if you dip slices of fruit into lemon juice, the acidic conditions will stop
enzyme browning
blanching- (plunging in boiling water for a short period), used to prepare veg for freezing. Natural ripening enzymes will cause the veg to lose colour, texture and flavour. Freezing will slow the enzymes but not stop the completely - blanching destroys ripening enzymes
What do moulds spoil?
bread, cheese and fruit
Where do yeasts grow?
on the surface of fruit such as grapes, blackberries and tomatoes
How can yeasts spoil fruit?
by fermenting the sugars turning them into alcohol and carbon dioxide
What happens when you cook/reheat food to 75 degrees?
- cooking food above 75 degrees bacteria
- its important to reheat properly and only one
- check its at least 75 degrees with a temperature probe
What happens during the danger zone (5 degrees-63 degrees)?
- bacteria can grow and multiply quickly in temperatures from 5 degrees to 63 degrees
- optimum temperature for bacteria growth is 37 degrees
What happens during chilling (0 degrees - 5 degrees)?
- keeping food between 0 degrees and 5 degrees slows down the growth of bacteria
- extends shelf life of the food
- chilling food doesn’t change its properties much (may have a harder texture)
What happens during freezing (-18 degrees)?
- stops bacteria growing
- bacteria becomes dormant
- greatly extends the shelf life of the food and the nutrients are not lost
- doesn’t kill bacteria, they become active again when the food defrosts
How can you use a fridge correctly?
- fridges should be kept between 0-5 degrees ideal for chilling foods
- keep food covered or stored in contains to prevent contaminating other foods
- dont led blood and juices of raw meat drip onto other food (always store at the bottom of the fridge)
How can you use a freezer correctly?
- set around -18 degrees
- food should have clear labels with the date they were frozen
- defrost meat and poultry thoroughly in a fridge
- if the food is partially frozen the recommended cooking time may not be sufficient to kill bacteria
What is the star rating on freezers and frozen foods to indicate when how long to store food?
storing in an ice box/freezer compartment in fridge- 1 week at -6 degrees, 1 month at -12 degrees
stored in a domestic freezer- 3 months at -18 degrees and until best before date -18 degrees or colder
What are ambient foods?
foods that can be safely stored at room temperature
What are some examples of ambient foods?
crisps, tinned vegetables, bread, pasta, cereal
How should ambient foods be stored?
stored in a sealed container - keeping the air out keeps the food fresh
What are the methods of preservation that can be used to extend the shelf life of ambient foods?
freeze drying- removes moisture from the food
canning foods- foods are sealed in cans and heated to kill of microorganisms
vacuum packing- food is put into plastic packaging and the air is sucked out
using chemicals- gherkins are pickled in vinegar, making it too acidic of microorganisms to grow rapidly
What is the use by date?
- shown on products with a short shelf life e.g high risk foods
- given as a safety warning, if you use food after this date it might not be safe so you run the risk of getting food poisoning
What is the best before date?
- shown on products with a longer shelf life e.g tinned foods
- given as a warning about quality, if you eat the food after this date its probably safe but may not be as nice as you would expect
- eggs however are risky to eat after their best before date as salmonella bacteria have multiplied to dangerous levels
How can cross contamination happen from a variety of different sources?
other contaminated food - raw meat juices can drip onto cooked food, high risk foods such as gravy can contaminate lower risk foods when added to a metal
utensils, equipment and work surfaces- using unclean equipment, dirty clothes on work surfaces or the same work surface, chopping board for raw meat separate to veg
people- poor personal hygiene, sneezing or coughing
pests- flies contaminate food by directly walking over, laying eggs
What steps should you take to reduce the risks when preparing food?
- follow personal hygiene procedures- wash your hands, wear a clean apron, hair net
- separate raw and cooked foods using coloured chopping boards
- wash raw veg
- use clean equipment and anti bac spray on surfaces
- de frost frozen food fully in the bottom of the fridge
What steps should you take to reduce the risks when cooking food?
- cook food at the right temperature and for the correct time
- food is cooked all the way through (cook thicker pieces of meat for longer than thin ones)
- test temp inside food using a temperature probe
How do you use a temperature probe?
- sterilise the probe before and after use
- insert it into the middle of the thickest part of the food
- leave the probe until the temp stabilises
- check the probe reaches 75 degrees
What steps should you take to reduce the risks when serving food?
- serve hot food straight away or keep it above 63 degrees for no longer than 6 hours
- if your serving food cold or storing it cool it down within 90 mins
- keep food covered to prevent flies or pests contaminating
- avoid wasting food, check waste bins are not overfilled
What are general symptoms of food poisoning?
sickness, diarrhoea, stomach cramps, fever
What is Campylobacter?
- most common
- food mainly in raw or undercooked poultry but also in other raw meat
- onset time is 2-5 days
What is salmonella?
- found in raw poultry, untreated milk and eggs
- onset time 6-72 hours
What is E-coli 0157?
- e coli live in the intestines of animals
- most types are harmless but e coli can cause kidney damage and death
sources include raw beef, untreated milk/water - onset time 1-3 days
What is Staphylococcus aureus?
- found on the skin, hair and in the noses of animals and people
- onset time is 1-6 hours
What is onset time?
the time it takes from ingesting the bacteria to when symptoms first appear
What is Listeria?
- found in soft cheeses, shell fish
- grow in cold temperatures like refrigerators
- pregnant women at a higher risk of infection, can lead to miscarriage
onset time is up to 70 days
What methods are in place to make foods that are contaminated with bacteria safe to eat?
pasteurisation- all the milk solid in supermarkets is pasteurised. milk is heated at around 72 degrees for 15 seconds to kill off any pathogenic bacteria before being chilled
vaccinations- british lion quality mark on egg shells and boxes is for hens that have been vaccinated against salmonella, so that it doesnt contaminate their eggs
Which cheese is safe to eat?
- blue bits on blue cheeses are due to moulds that have been added to them
- mould gives the cheese a creamy texture and a distinctive sharp, tangy taste
How does the production of many varieties of bread rely on the properties of yeast as a raising agent?
- yeast, flour and water form a dough
- salt is added for flavour but also to strengthen the gluten in the dough
- with the ideal conditions the yeast starts to grow
- yeast ferments the sugar to produce carbon dioxide - this gas is what causes the bread to rise
How is bacteria used to make yogurt?
- milk is pasteurised to kill off any bad bacteria
- non pathogenic bacteria are added
- these bacteria ferment lactose and produce lactic acid
- the lactic acid acts on the proteins in the milk to thicken it and gives it a sour or tangy taste
- probiotics (live bacteria) are supplement in some yogurts which are said to give health benefits