GCSE Food hygiene & safety Flashcards

1
Q

How is cheese made?

A
  • by separating milk into solid, curds and liquid
  • by coagulating the casein protein in milk
  • acidifying the milk helps the separation
  • bacteria are added to the milk
  • bacteria convert the lactose into lactic acid
  • rennet is added which contains active enzymes to speed up the coagulation
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2
Q

How is yogurt made?

A
  • milk is heated to 80 degrees
  • this denatures and changes the structure of the protein
    -this ensure the yogurt is set smoothly and it kills any unwanted bacteria
  • milk is cooled and bacteria is added
  • milk is kept at 45 degrees for several hours allowing it to ferment, before its cooled
  • during fermentation, the harmful bacteria convert the milk sugar into lactic acid
  • this helps the milk coagulate and slightly set, producing yogurt
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3
Q

What do microorganisms include?

A
  • bacteria, moulds and yeast
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4
Q

What are the 5 conditions needed for microorganisms to grow and multiply?

A
  • temperature
    -moisture
    -food
    -right pH
    -time
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5
Q

What can you change to stop or slow growth of microorganisms?

A
  • use a fridge to change the temperature
    -pickle the food in vinegar to change the pH
    -add salt (salt absorbs water), which removes the moisture from the food
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6
Q

What are high risk foods?

A
  • foods that are ready to eat, that if not stored correctly could grow harmful bacteria
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7
Q

What are some examples of high risk foods?

A
  • cooked meat (fish and poultry)
    -dairy products
    -shellfish
    -cooked rice
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8
Q

When can foods only be classed as “high risk”?

A
  • once they are cooked (ready to eat)
    -raw chicken is not high risk food because it has not been cooked
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9
Q

How can you check there are no visible signs of spoilage when buying food?

A
  • fresh meat should be brightly coloured and have a fresh smell
    -fresh fish should have a shiny skin and red gills
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10
Q

What are enzymes?

A
  • Enzymes are special proteins that act as biological catalysts- they speed up chemical reactions
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11
Q

What do enzymes in fruit cause? What is an example of this?

A
  • cause them to ripen, which affects sweetness, colour and texture of the fruit

e.g- unripe bananas are green and firm, enzymes break down starch inside them which makes the banana softer and sweeter.

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12
Q

What does enzymic browning cause?

A
  • when you slice fruits the oxygen in the air will turn the fruit brown
    -enzymes inside this fruit speed up this process
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13
Q

How does adding an acid slow/prevent un wanted effects on enzymes?

A
  • enzymes work best at a certain pH
  • if you dip slices of fruit into lemon juice, the acidic conditions will stop enzymic browning
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14
Q

How does blanching (boiling water for a short period of time) slow/prevent un wanted effects on enzymes?

A
  • prepare vegetables for freezing
    -natural ripening enzymes will cause veg to loose colour, texture, flavour
  • freezing slows enzymes but does not slow them completely
    -branching destroys ripening enzymes
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15
Q

What are mould and yeast?

A
  • microorganisms
    -in right conditions they can grow and multiply rapidly
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16
Q

What can waste products from moulds cause?

A
  • food poisoning
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17
Q

What happens at 75 degrees when cooking/reheating?

A
  • cooking food above 75 degrees kills bacteria
  • its important to reheat food properly and only once
    -check food is above 75 degrees with a temperature probe?
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18
Q

What happens in the danger zone at 5 degrees to 63 degrees?

A
  • bacteria can grow an multiply quickly in these temperatures
    -(danger zone)
    -hot food should be held above 63 degrees
    -optimum temp for bacteria growth is 37 degrees
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19
Q

What happens when chilling (0 degrees to 5 degrees)?

A
  • slows down growth of bacteria
    -extends shelf life of food
    -doesn’t change properties much, but may have a slightly harder texture
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20
Q

What happens during freezing (-18 degrees)?

A
  • stops bacteria growing
    -become dormant
    -greatly extends shelf life of food
    -nutrients arent lost
    -doesnt kill bacteria, they become active again when food is lost
21
Q

How do you use a fridge?

A
  • should be kept between 0-5 degrees
  • keep food covered or stored in containers to prevent contaminating other foods
    -always store meat and poultry at the bottom of the fridge?
22
Q

How do you use a freezer?

A

-set around -18 degrees
-clear labels with date of frozen
defrost meat and poultry thoroughly in a fridge
domestic freezer- 3 months
icebox- 1 week

23
Q

What are ambient foods?

A
  • foods that can be safely stored at room temperature
24
Q

What are some examples of ambient foods?

A
  • crisps, bread, pasta, cereal, sugar
25
Q

How should ambient foods be stored?

A

-in a sealed container
-cool/dry place

26
Q

What are some methods of preservation that are used to extend shelf life of some foods?

A

freeze drying- remove moisture from food

-canning foods-food sealed in cans and heated off to kill microorganisms

-vacuum packing- food is put into plastic packaging, air is sucked out

-using chemicals- gherkins are pickled in vinegar making it too acidic for microorganisms to grow properly

27
Q

What is a use by date?

A
  • shown on products with short shelf life e.g high risk foods
    -given as a safety warning
28
Q

What is a best before date?

A
  • shown on product with long shelf life
    -given as a warning about quality
    -may be safe, but not as nice
    -eggs un healthy after use by date
29
Q

Why can cross contamination occur?

A
  • other contaminated foods (meat juices dripping)
    -utensils/work surfaces- unclean equipment, chopping board for raw meat and ready to eat foods
    -people- poor personal hygiene
    -pests- flies contaminate food by walking/eating over it
30
Q

What is cross contamination?

A
  • Transfer of bacteria from one source to another food.
31
Q

How should you prepare food to avoid the risk of contaminating?

A
  • personal hygiene like washing your hands
    -separate raw and uncooked food
    -wash raw veg
  • use clean equipment
    -defrost food thoroughly
32
Q

How should you cook food to avoid the risk of contamination?

A
  • cook food at right temperatures and for correct time
    -make sure food is cooked through
    -test temp inside
33
Q

How should you cook serve food to avoid the risk of contamination?

A
  • serve hot food straight away
    -cool food down within 90 mins before storing
    -keep food covered to prevent flies
    -avoid wasting/check bins are not overfull
34
Q

What are the general symptoms of food poisoning?

A
  • sickness, diarrhoea, stomach cramps
35
Q

What is Campylobacter?

A
  • most common food poisoning
    -found in raw/uncooked poultry and meat
    -onset time is 2 days
36
Q

What is salmonella?

A
  • found in raw poultry, milk and eggs
  • onset time is 6-72 hours
37
Q

What is Listeria?

A
  • found in cheese, shellfish
    -grow in cold temperatures (refrigerator)
    -pregnant women at higher risk
    -onset time is up to 70 days
38
Q

What is E. Coli?

A

-lives in the intestines of animals
-most types are harmless
-e.coli 0157 can cause kidney damage and death
-raw beef, unwashed veg
-onset time is 1-3 days

39
Q

What is staphylococcus aureus?

A
  • found in skin, hair and in the noses of animals and people
    -onset time is 1 to 6 hours
40
Q

What is pasteurisation?

A
  • all milk sold in supermarkets is pasteurised
    -milk heated at 72 degrees for 15 seconds to kill pathogenic bacteria
41
Q

What are vaccinations?

A
  • British lion quality mark on egg shells and boxes is for hens that have been vaccinated against salmonella
42
Q

What are the blue bits on cheese?

A
  • moulds that have been added
  • give the cheese a creamy texture and a distinctive taste
43
Q

Why is salt added to bread dough?

A
  • added for flavour, but also to strengthen the gluten in the dough
44
Q

How does the yeast ferment when making bread rise?

A
  • ferments sugar to produce carbon dioxide
45
Q

Why is non pathogenic bacteria added to milk?

A
  • bacteria ferment lactose and produce lactic acid
    -lactic acid acts on the proteins in the milk to thicken it
46
Q

What are probiotics?

A

-live bacteria
- supplement in some yogurt which are said to give health benefits

47
Q

What is an example of physical contamination?

A
  • when a carrot gets dug up and a stone comes out with the soil
48
Q

What is an example of chemical contamination?

A
  • washing up liquid on the plate and it transferring to the food
49
Q

What is an example of Biological contamination?

A
  • bacteria growing and multiplying with food