food safety

Question 1

what conditions do microorganisms (bacteria, moulds and yeasts) need for growth and multiplication

Answer 1

the right pH (not too alkaline/acidic)
moisture
plenty of food
warmth
time

Question 2

slowing/stopping enzymes from working

Answer 2

enzymes are made from protein

• adding an acid - enzymes work best at certain pHs
• blanching - freezing slows down the natural ripening enzymes, blanching destroys them

Question 3

how do yeasts spoil fruit

Answer 3

they ferment the sugars and turn them into alcohol and CO2

Question 4

cooking/reheating food

Answer 4

above 75˚C kills bacteria

food should only be reheated once and to 75˚C for 3 minutes

Question 5

chilling food

Answer 5

keeping food between O˚C and 5˚C slows down growth of bacteria
extends shelf life
doesn’t change properties much - looks and tastes the same but may have a harder texture

Question 6

the danger zone

Answer 6

5˚C to 63˚C
optimum temp for bacterial growth is 37˚C
hot food should be held above 63˚C

Question 7

freezing

Answer 7

below -18˚C
bacteria becomes dormant - doesn’t kill it
greatly extends shelf life of food and nutrients aren’t lost

Question 8

fridges

Answer 8

should be 0˚C to 5˚C
keep food covered/in containers to prevent contamination
raw meat, fish and poultry should be stored on the bottom shelf

Question 9

freezers

Answer 9

set around -18˚C

food should have clear labels with the date they were frozen

meat and poultry should be thoroughly defrosted in the fridge - if it is partially frozen, the recommended cooking time may be insufficient to kill bacteria

if cooking from frozen - follow the ‘cooking from frozen’ time

Question 10

star ratings for food storage

Answer 10

• 1 week, -6˚C in an ice box/ freezer compartment of fridge
• • 1 month, -12 ˚C in an ice box/ freezer compartment of fridge
• ** 3 months, -18˚C in a domestic freezer
• *** until ‘best before’ date on frozen foods, -18˚C or colder

Question 11

methods of preservation

Answer 11

freeze drying - removes moisture

canning foods - heating when canning kills off microorganisms

vacuum packing - lack of oxygen limits growth of micro organisms

chemicals - eg. pickling in vinegar, wrong pH for fast growth of microorganisms

Question 12

use by date

Answer 12

on products with a short life, eg. high risk foods

eating food after this date may be unsafe and there is a risk of food poisoning

Question 13

best before date

Answer 13

on products with a longer shelf life, eg. tinned foods

warning for quality - food is probably safe after this date but may lose quality

eggs - risky to eat post best before, as salmonella bacteria may have multiplied to dangerous levels

Question 14

safety and hygiene when preparing food

Answer 14

• wash hands, wear a clean apron, hat/hair net, remove jewellery, cover cuts with a blue plaster
• separate raw and cooked foods
• use coloured chopping boards
• clean equipment and antibacterial spray to sanitise work surfaces
• defrost froze food fully in the bottom of the fridge, away from other food

Question 15

serving food safely and hygienically

Answer 15

• serve food immediately/keep it above 63˚C for no more than 2 hours
• if serving food cold/storing it - cool it down within 90 minutes
• keep food covered to prevent contamination from flies/pests - preferable keep it in the fridge
• avoid wasting food
• check that waste bins aren’t overfilled

Question 16

campylobacter

Answer 16

• uk’s most common cause of food poisoning
• mainly found in raw/undercooked poultry but also other meat and untreated milk/water

onset time: 2-5 days

Question 17

E. coli

Answer 17

• E. coli live in intestines of animals
• most are harmless but E. coli O157 can cause kidney damage and death
• sources - raw beef, untreated milk/water, unwashed vegetables, salad leaves

onset time: 1-10 days

Question 18

staphylococcus aureus

Answer 18

• live on skin and hair and in the noses of animals and people
• poor personal hygiene can contaminate food

onset time: 1-6 hours

Question 19

salmonella

Answer 19

• found in raw poultry, untreated milk and eggs

onset time: 6-72 hours