Food Safety

Question 1

What microorganisms need to grow

Answer 1

Warm temp
Moisture
Food
Right pH
Time

Changing these conditions will slow or stop the growth of microorganisms eg. use a fridge to change the temp. pickle to food in vinegar to change the pH, add salt to remove moisture.

Question 2

Pathogenic microorganisms

Answer 2

Can spoil food and cause food poisoning.

Question 3

High risk foods

Answer 3

High risk foods if not stored correctly could grow harmful bacteria. They have ideal conditions for bacteria - moist and high in protein.

High risk foods include:
cooked meat, fish and poultry.
Dairy products
Gravies. stocks and sauces
Shellfish 
Cooked rice

They have a short shelf life because if kept for a long time bacteria could multiply to dangerous levels.

Raw food is not classed as high risk as you do not eat it raw.

Fresh meat should be brightly coloures, firm and have a fresh smell.
Fresh fish should have shiny skin, red gills , clear eyes and smell clean or slightly salty.

Question 4

Enzymes in ripening

Answer 4

Enzyms are biological catalysts - they are proteins that speed up chemical reactions.

Enzymes in fruit cause them to ripen, affecting the sweetness, colour and texture.

Eg. unripe bananas are green and firm. Enzymes break down the starch inside them, making them softer and sweeter.

Question 5

Enzymes in browning

Answer 5

When you slice fruits the oxygen in the air will turn the fruit brown (oxidation). Enzymes speed up this process.

Leaving some fruit to overripen will also give them a brown colour (bananas)

Question 6

How to slow or stop and enzyme

Answer 6

Adding an acid-enzymes work best at certain pHs. If you dip slices of fruit into lemon juice, the acidic conditions will stop enzymic browning.

Blanching- plunging into boiling water for a short period, used to prepare vegetables for freezing. natural ripening enzymes cause veg to lose colour, texture, flavour and nutrients over time. Freezing slows down the enzymes but does not stop them completely. Blanching destroys the ripening enzymes, so vegetables will retain their colour and nutrients.

Question 7

Mould and yeast in food spoilage

Answer 7

They are both microorganisms, so with the right conditions they can grow quickly.

Moulds spoil bread, cheese and fruit - they change to look ,smell and taste. has a fuzzy appearance.

Even if you scrape off the mould, toxins may still remain which can cause food poisoning.

Yeasts commonly grow on the surface of fruit and spoils fruit by fermenting the sugars into alcohol and carbon dioxide.

Can be prevented by storing it correctly, eg, storing bread in cool, dry conditions, fruits in the fridge.

Question 8

Cooking food

Answer 8

Cooking food above 75 degrees kills bacteria.

Must reheat food properly and only once. Reheat food to above 75 degrees c for at least 3 minutes.

Check with a temperature probe.

Question 9

Danger zone

Answer 9

Bacteria grow and multiply quickest in temps between 5 and 63 degrees c.

Hot food should be held above 63 degrees c.

Optimum temp for bacterial growth is 37 degrees C.

Question 10

Chilling

Answer 10

Keeping food between 0 and 5 degrees c slows down the growth of bacteria, which extends the shelf life.

Chilling does not change its properties much, may have a harder texture.

Question 11

Freezing

Answer 11

Freezing food below -18 degrees c stops bacteria growing.

greatly extends the shelft life and nutrients arn’t lost.

Does not kill the bacteria, become active again when the food defrosts.

Question 12

Fridges

Answer 12

Should be between 0 and 5 degrees C.
Keep food covered or stored in containers to prevent it contaminating other foods.

Store raw meat, poultry and fish on the bottom shelf to prevent the blood and juices from dripping onto other food.

Question 13

Freezers

Answer 13

Set around -18 degrees C.

Foods should have clear labels with the dates they were frozen.

Defrost meat and poultry thoroughly in a fridge, if it is partially frozen the reccomended cooking time may not be sufficient to kill the bacteria.

Question 14

Industrial processes to chill or freeze food

Answer 14

Cook freezing-food is cooked and rapidly frozen to below -18 degrees.

Blast- chilling- rapidly cools cooked food to below 5 degrees within 90 minutes.

Accelerated freeze-drying- food is rapidly frozen and dehydrated to remove moisture from the food. adding water restores the food to its original texture and taste.

Question 15

Preservation methods

Answer 15

Drying 
Canning/bottling
Pickling
jam-making
Vacuum packing
Modified atmospheric packaging

these either remove the moisture or have been processed or preserved to make it difficult for microorganisms to grow.

these give the foods longer shelf lifes.

Question 16

Drying

Answer 16

Food is dehydrated. The lack of moisture makes it difficult for microorganisms to grow.

Methods of drying include smoking and freeze-drying.

Question 17

Canning/bottling

Answer 17

Food is sealed in a can or jar and heated to kill of microorganisms.

Question 18

Pickling

Answer 18

Food is plunged in brine or vinegar making it too acidic for microorganisms to grow quickly.

Question 19

Jam-making

Answer 19

Fruit is boiled with sugar and pectin, and sealed in a glass jar. The high sugar content prevents microorganisms from growing quickly.

Question 20

Vacuum packing

Answer 20

Food is put unto plastic packing and the air is sucked out. Some microorganisms can’t survive without oxygen.

Question 21

Modified atmospheric packaging

Answer 21

Food is packaged with a specific mixture of gases (different amount of nitrogen, carbon dioxide and oxygen) depending on the food.

Question 22

Use by date

Answer 22

the use by date is shown on products with a short shelf life.

it is given as a safety warning. Eating the food after this date means i might not be safe and you might get food poisoning.

Question 23

Best before date

Answer 23

The best before date is shown on products with a longer shelf life.

Its given as a warning about quality. if you eat it after this date it is probably safe but may not be the best quality eg. biscuits may be soft.

Eggs are risky to eat after the best before date - salmonella bacteria may have multiplied to dangerous levels.

Question 24

Cross contamination

Answer 24

When you pass bacteria from raw food to work surfaces, equiptment and your hands. this is then easily transferred to other foods.
Cross contamination can happen through:
Other contaminated food:raw meat juices can drip onto cooked food. high risk foods such as gravy can contaminate other lower risk foods when added to a meal.

Utensils, equipment and work surfaces: using unclean equipment, dirty cloths on work surfaces or using the same chopping board for raw meat as ready to eat foods.

People- poor personal hygiene, sneezing, coughing, unwashed hands

Pests- flies, rodents contaminate food directly by walking over it, eating it or laying eggs and dropping on work surfaces

Question 25

Preventing cross contamination- preparing

Answer 25

Follow person hygiene procedures- wash hands, wear a clean apron, wear a hat it hair net, remove jewellery, cover cuts

Separate Rae and cooked foods, use coloured chopping boards for different food groups

Wash raw vegetables thoroughly as traces of soil contain bacteria

Use clean equipment and an antibacterial spray to sanitise work surfaces

defrost frozen food fully, in the bottom of the fridge, away from other food

Question 26

Preventing cross contamination- cooking

Answer 26

Cook food at the right temperature for the right time

Make sure food is cooked all the way through

Test the temperature inside using a temperature probe.

Question 27

Preventing cross contamination - serving

Answer 27

Serve hot food straight away or keep it above 63 degrees c for not longer than 2 hours

If your serving food cold or storing it, cook it down within 90 minutes

Keep food covered go prevent flies or other pests contaminating it

Avoid wasting food, check that bins are not overfilled

Question 28

Food poisoning

Answer 28

Bacteria causes food poisoning