Food Safety Flashcards
What microorganisms need to grow
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.
Pathogenic microorganisms
Can spoil food and cause food poisoning.
High risk foods
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.
Enzymes in ripening
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.
Enzymes in browning
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)
How to slow or stop and enzyme
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.
Mould and yeast in food spoilage
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.
Cooking food
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.
Danger zone
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.
Chilling
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.
Freezing
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.
Fridges
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.
Freezers
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.
Industrial processes to chill or freeze food
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.
Preservation methods
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.
Drying
Food is dehydrated. The lack of moisture makes it difficult for microorganisms to grow.
Methods of drying include smoking and freeze-drying.
Canning/bottling
Food is sealed in a can or jar and heated to kill of microorganisms.
Pickling
Food is plunged in brine or vinegar making it too acidic for microorganisms to grow quickly.
Jam-making
Fruit is boiled with sugar and pectin, and sealed in a glass jar. The high sugar content prevents microorganisms from growing quickly.
Vacuum packing
Food is put unto plastic packing and the air is sucked out. Some microorganisms can’t survive without oxygen.
Modified atmospheric packaging
Food is packaged with a specific mixture of gases (different amount of nitrogen, carbon dioxide and oxygen) depending on the food.
Use by date
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.
Best before date
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.
Cross contamination
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
Preventing cross contamination- preparing
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
Preventing cross contamination- cooking
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.
Preventing cross contamination - serving
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
Food poisoning
Bacteria causes food poisoning
