food safety Flashcards
in what conditions do microorganisms grow?
1.warm temperature
2.plenty of moisture
3.plenty of food
4.the right pH
5.enough time (bacteria split every 10-20 minutes)
how can you slow or stop growth of microorgansims?
change any one of the optimum conditions
what is a microorgansim?
bacteria, mould, yeast, most harmless but some pathogenic and spoil food and give food poisoning
how can you change conditions that bacteria grow in?
use fridge to change temp, pickle the food to change pH, add salt to absorb moisture and dry out food
what is a high risk food?
ready-to-eat foods that, if not stored correctly, could grow harmful bacteria, they are moist and high in protein(food)
what are examples of high risk foods?
cooked meat, fish and poultry
dairy products
gravies, stocks and sauces
shellfish
cooked rice
is raw chicken a high risk food?
no only once cooked as you dont eat it raw
how do you know meat is fresh?
brightly coloured, firm, fresh smell
how do you know fish is fresh?
shiny skin, red glls, clear eyes, clean/salty smell
what is an enzyme?
a special protein that acts as a biological catalyst
what is ripening?
.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 making banana softer & sweeter
what is browning?
.when you slice fruits (apples, pears etc.), the oxygen in the air will turn the fruit brown, enzymes inside the fruit speed up this process.
.leaving some fruit (bananas, avocados etc) to overripen will give them a brown colour too
how do you control enzyme activity?
add an acid-if you dip fruits into lemon juice the acidic conditions stop enzymic browning (enzymes work best at specific pH)
blanching-(plunging into boiling water for short time period) used to prepare veg for freezing, natural ripening enzymes cause veg to lose colour, texture, flavour and nutrients over time. freezing slows enzymes
how do moulds spoil foods?
change looks, smell and taste of food, ‘fuzzy’ appearance, even if scraped off toxins may still remain and cause food poisoning
how do yeasts spoil foods?
ferment fruits by fermenting sugars and turning into alcohol or carbon dioxide
what is the danger zone?
5-63 degrees c
optimum temp is 37 degrees c for bacterial growth
what temperature should you chill foods at?
0-5 degrees c
slows bacterial growth and extends shelf life
what temperature should you freeze food at?
below -18 degrees c
bacteria become dormant and stop growing, extends shelf life
what temperature should you cook or reheat foods to?
75 degrees c
this kills bacteria
only reheat once at above 75 for atleast 3 minutes
how can you check food temperature?
use a temperature probe in thickest part of food usually centre and clean before and after use
how should you store food in the fridge?
keep foods covered or stored in containers to prevent contaminating other foods and dont let blood and juices of raw meat drip onto other foods, store meats on bottom shelf
how should you store foods in the freezer?
food should have clear labels with freeze date, defrost thoroughly in fridge (meat and poultry) if food is slightly frozen recommended cooking time may not kill all bacteria
what are ambient foods?
1.should still be kept in sealed container - keeping all air out
2.they should be stored in a cool, dry place - aany moisture will help mould growth
3.can eat after months or years safely
what are methods of preservation for ambient foods?
freeze-drying - removes moisture
canning foods - sealed and heated to kill microorganisms
vacuum packing - plastic packaging with air sucked out
chemicals - e.g. adding vinegar to gherkins making it too acidic for microorgansisms
what is the ‘use by date’?
shown on products with a short shelf life e.g. high risk foods, its given as a safety waring and if you use food after this date it may not be safe and risks 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 might not be as nice as expected.
what is cross-contamination?
when working with food, its easy to pass bacteria from raw food to work surfaces, equipment and your hands. bacteria are then easily transferred to other food
how can cross-contamination happen?
other contaminated food-raw meat juices drip onto cooked food, high risk foods like gravy can contaminate low risk foods when added to a meal
utensils, equipment and work surfaces - using unclean equipment, dirty cloths on surfaces and chopping boards for raw meat and ready-to-eat foods
people-poor personal hygiene unclean hands and sneezing or coughing
pests-flies, rodents etc. contaminate food diretly by walking over/eating it or laying eggs and droppings on work surfaces
how do you prepare food safely?
1.follow personal hygeine procedures - wash your hands, wear a clean apron, wear a hat or hair net to cover hair, remove jewellery and cover cuts
2.separate raw and cooked foods and use coloured chopping boards for different food groups
3.wash raw veg thoroughly, even soil could contain bacteria
4.use clean equipment and an antibacterial spray to sanitise surfaces
5.defrost frozen foods fully in bottom of fridge
what chopping board colours go with different food groups?
red=raw meat
brown=raw veg
blue=raw fish
yellow=cooked meat
green=salad and fruits
white=bakery and dairy
purple=allergans
how do you cook food safely?
1.cook at right temp and correct time
2.make sure its cooked all the way through, cook thicker pieces of meat longer
3.test temp inside food with food probe
how do you serve food safely?
1.serve hot straight away or keep abouve 63 degrees c for no longer than 2 hours
2.if serving cold or storing cool within 90 minutes
3.keep food covered to stop flies or other pests contaminating put in fridge
4.try avoid wasting food
what are the symptoms of food poisoning?
sickness, diarrhoea, stomach cramps, fever
in extreme cases-death
how do you get food poisoning?
contaminated food containing pathogenic bacteria can take a few hours or several days before symptoms appear
what are the 5 main types of bacteria?
Campylobacter
Salmonella
Listeria
E. coli 0157
Staphyllococcus aureus
what is campylobacter?
-most common cause of food poisoning in the uk
-found in mainly raw or uncooked poultry, also other raw meat and untreated milk/water
onset time: 2-5 days
what is salmonella?
-found in raw poultry, untreated milk and eggs
onset time: 6-72 hours
what is E. coli?
-lives in intestines of animals
-most types are harmless but E. coli 0157 causes kidney disease and death
-sources: raw beef, untreated milk/water, inwashed veg/salad leaves
-onset time: 1-3 ays
what is staphylococcus aureus?
-found on the skin, hair and in nose of animals and people
-onset time: 1-6 hours
what is Listeria?
-found in soft cheese, pate and shell fish
-unlike other bacteria it can grow in cold temps e.g. the fridge
-pregnant women at higher risk of infection, can lead to miscarriage and health problems with baby
-onset time: up to 70 days
how do you control bacteria?
pasteurisation-all milk sold in super markets is pasteurised, it is heated at about 72 degrees c for 15 seconds to kill off pathogenic bacteria before being cooled
vaccinations-the british lion quality mark on egg shells and boxes is for hens vaccinated against salmonella, so eggs not contaminated
why are some moulds important?
some are safe to eat and are important in the production of cheeses
-the blue bits on blue cheese (e.g. Gorgonzola, Stilton) are due to moulds that have been added to them
-the mould gives the cheese a creamy texture and sharp tangy taste
why are some yeasts important
production of many breads rely on yeast as a raising agent
-yeast, flour and water form dough, salt added to flavour and strengthen gluten in the dough
-with ideal conditions yeast grows
-fermenting sugar to produce carbon dioxide, this gas causes bread to rise
why are some bacterias important?
non-pathogenic bacteria is useful in turning milk into cheese & yoghurt
-milk pasteurised to kill bad bacteria
-non-pathogenic bacteria are added
-bacteria ferment the lactose and produce lactic acid
- lactic acid acts on the proteins in the milk to thicken and give sour taste
-probiotics are supplement in some yoghurts which said to give health benefits
