Section 3: Food spoilage Flashcards
microorganisms and what are examples of them?
tiny living things found in everything that can be pathogenic, causing food spoilage
e.g bacteria, moulds, yeast
What are the 5 conditions needed for microorganisms to grow and multiply quickly/
- warm temperature
- moisture
- food
- right PH
- enough time
How can you stop the growth of microorganisms?
- use a fridge to change the temp
- pickle fod in vinegar to reduce PH
- add salt to dry food out
What are high risk foods and what are examples of them?
foods that are moist and high in protein for example: cooked meat, fish and poultry, dairy, cooked rice
When can a food be described as high risk?
when it has been cooked and is ‘ready to eat’.
How can you check that there are no visible signs of food spoilage?
fresh meat- should be rightly colour, firm and have a fresh smell
fresh fish- should have shiny skin, red gills, clear eyes and smell clean or slightly salty
What can enzymes cause in foods?
ripening
browning- oxygen in air turns fruit and veg brown and enzymes in food speed this up
How can you slow enzymes or stop them from working?
add acid as enzymes work at specific PH- you can dip fruits and veg in lemon juice
blanching- slows down enzymes and destroys ripening enzymes
How can moulds and yeasts spoil food?
they are microorganisms (fungi).
mould- spreads to in food changing the look, smell and taste of food. can have fuzzy appearance
yeast- grown on surfaces of foods. ferments sugars turning them into alcohol and carbon dioxide.
What temperature should you heat food to to kill bacteria?
75 degrees
What us the danger zone for bacteria to grow?
5 to 63 degrees
What is the optimal temperature for bacteria to grow in?
37 degrees
What temperature should foods be chilled and frozen at?
chilled at 0 to 5 degrees
frozen at minus 18 degrees as bacteria will become dormant and stop growing
What shelf should meat and poultry be kept on?
bottom shelf to prevent dripped of blood and juices of raw meat
What are ambient foods?
foods that can be stored safely at room temperature but should still be kept in a sealed container
What are 4 methods of preservation of food?
freeze-drying -removes moisture from food
canning foods- sealed in cans and heated to kill microorganisms
vacuum packing- plastic packaging with air sucked out
using chemicals- gherkins are put into vinegar which make it too acidic for microorganisms to grow
What is the use by date?
-date shown for products with a short shelf life
-given as safety warning of food poisoning
What is the best before date?
-date shown on products with a lower shelf life
-given as warning about quality of food but can be eaten after the best before date
What is cross-contamination?
when bacteria is passed onto food
What sources can cross contamination occur from?
-other contaminated food
-utensils, equipment, work surfaces
-people (poor personal hygiene or coughing and sneezing
-pests (flies, rodents)
How should you prepare food to avoid cross-contamination?
-follow personal hygiene procedures
-separate raw and cook foods
-use coloured chopping boards
-use clean equipment
How should you cook food to avoid cross-contamination?
-cook at right temperatures
-make sure food is cooked all the way through
-test temperature of food using a probe
How should you serve food to avoid cross-contamination?
-serve hot food right away
-if you’re storing foo cold do it within 90 mins
-keep food covered to prevent pests
What are the general symptoms of food posioning?
sickness, diarrhoea, stomach cramps and fever
What is campylobacter bacteria?
-most common cause of food poisoning in the uk
- found many in undercooked or raw meat
-onset time of 2 to 5 days
What is E.coli bacteria?
-live in intestines of animals
-version o157 can cause kidney damage and death
-found in raw beef, untreated milk/ water, unwashed veg and salad leaves
-onset time of 1 to 10 days
What is salmonella bacteria?
-found in raw poultry, untreated milk and eggs
-onset time of 6 to 72 hours
What is Staphylococcus bacteria?
- staphylococcus aureus lives on the skin, hair and noses of animals and people
- caused by poor personal hygiene
-onset time of 1 to 6 hours
What is Listeria bacteria?
- can be found in soft cheeses, pate and shellfish
- can grow in cold temperatures like a fridge
-can lead to miscarriage or health problems in child
-onset time of up to 70 days
What are methods for controlling bacteria?
pasteurisation- milk is heated at 72 degrees for 15 secs to kill off any pathogenic bacteria before being chilled
vaccinations- British Lion Quality mark egg shells and boxes to say if they have been vaccinated against salmonella
Some moulds are safe to eat, what is an example of this?
blue bits on blue cheese, give cheese a creamy texture and distinctive sharp and tangy taste
Which microorganism is good for baking?
yeast
How is bacteria used to make yoghurt and cheese?
- Milk is pasteurised to kill off any ‘bad’ bacteria.
- Non-pathogenic bacteria are added fermenting lactose and producing lactic acid.
- The lactic acid acts on the proteins in the milk to thicken it and gives it a sour or tangy taste.
4.Probiotics (live bacteria) are a supplement in some yoghurts which are said to give health benefits.
