S-Cool Revision Summary

S-Cool Revision Summary

Food packaging

  • Gives food a longer shelf-life.
  • Protects food during transportation and storage.
  • Keeps food clean from dirt and bacteria.
  • Provides information.
  • Advertises the product.
  • Holds the food in place.

The following table is a list of the different packaging types and their advantages and disadvantages





Used for:



Can be waxed to make it waterproof, easy to print on, cheap, can be recycled.

Not very strong.

Flour, sugar, loose fruit and vegetables.



Lightweight, easily shaped, easy to print on, can be recycled.

Soggy if wet.

Frozen foods, cereals, cakes, fruit juice.



See-through, can be coloured, cheap, can be recycled, easily moulded.

Can break easily. Often needs a paper or plastic film label. Heavy.

Jam, wine, pickles, milk, cooking sauces.

Metal (Tinplate and aluminium)


Heat treated to preserve the contents, can be recycled, strong, lightweight.

Can rip (foil lids), often needs a utensil to open it, needs a paper label. Heat treatment can alter texture and taste.

Yoghurt lids, tinned foods, bottle tops.

The UK Food Labelling Regulations 1996 state that the following information must be shown...

  • 1. Food Product Name.
  • 2. List of ingredients.
  • 3. Storage conditions.
  • 4. Shelf life.
  • 5. Instructions for use.
  • 6. Name and address of manufacturer.
  • 7. Place of origin.
  • 8. Weight or volume.

The following information is voluntary

  • 1. A picture.
  • 2. Recipe ideas.
  • 3. Bar codes.
  • 4. Environmental and recycling information.
  • 5. Nutritional information.
  • 6. Lot or batch mark.
  • 7. Opening instructions.
  • 8. Special information.

Preservation of food

Food needs to be preserved...

  • So that surplus foods from good harvests can be stored and then used in times of shortage.
  • So that we can enjoy seasonal fruits and vegetables all year round.
  • To enable it to be transported long distances without it decaying (and spillage!).
  • To allow it to be stored in the home for long periods without going off.

There are six main ways in which food can be preserved...

  1. High temperatures
    • Canning
    • Bottling
    • Pasteurisation
    • Ultra Heat Treatment (UHT)
    • Sterilisation
  2. Low temperatures
    • Freezing
    • Chilling
  3. Removing moisture
    • Drying
    • Accelerated Freeze Drying (AFD)
  4. Use of chemicals
    • Pickling
    • Salting
    • Smoking
    • Sugar
  5. Controlling the atmosphere
    • Vacuum Packing
    • Modified Atmosphere Packaging (MAP)
  6. Irradiation

Methods of preserving food...

Method and
How it works:



Used for:

Heat kills bacteria and enzymes.

Lasts for many years.

Can cause changes in colour and texture. Loss of Vitamin C.

Fish, meat, fruit, vegetables, milk.

Heat kills bacteria and enzymes.

Lasts for many years.

Can cause changes in colour and texture. Loss of Vitamin C.

Fruit and vegetables.

Most bacteria killed at 72 degrees Celsius.

Little effect on flavour.

Not all bacteria killed.

Milk, cream, orange juice.

All bacteria killed at 132 degrees Celsius.

Lasts for several months.

Changes taste slightly.

Milk, fruit juices.

Food is heated to 104 degrees Celsius for 40 minutes.

Extends life of milk to about 10 days.

Gives a creamy flavour and colour.

Milk, fruit juices.

Stops bacteria and enzymes activity. Domestic freezers are at -18 degrees Celsius.

Foods can be frozen for many months. Little loss of vitamins.

Slow freezing breaks down cells and changes the texture of foods.

Ready prepared meals, fish, meat, vegetables, fruit, ice-creams.

Temperatures of 1 to 8 degrees Celsius slow bacteria growth.

Good colour and flavour kept.

Short storage life.

Ready prepared meals, such as Lasagne.

Removal of moisture stops bacteria growth.

Last for long periods of time.

Most Vitamin C lost. Must be kept dry.

Soups, pasta, beans packet desserts.

Food is frozen and then dried quickly.

Good colour and flavour.

Can be expensive.


Increases acidity of food.

Long shelf life.

Very strong flavour.

Onions, cabbage, olives.

Reduces water content by osmosis.

Long shelf life.

Food needs to be soaked before cooking.

Meat, fish, green beans.

Slow method, which prevents bacteria growth.

Adds flavour.

Kills Vitamins B and C.

Bacon, cheese, fish.

More than 60% will stop micro-organism growth.

Long shelf life.

High temperatures in jam making kill Vitamin C.

Jams, marmalade, crystallised fruits.

Vacuum packs:
Removes all oxygen.

Retains vitamins.

Often still needs refrigeration

Bacon, fish.

Replaces oxygen with nitrogen and carbon dioxide.

Colour and flavour are good.


Meat, salads, minced beef, and bacon.

Radiation kills, bacteria and pests.

Delays ripening of fruit and sprouting of vegetables.

Not in general use. Consumer safety worries.

Strawberries, vegetables and spices.

Food poisoning

10 main causes of food poisoning

Cause: Prevention:
Preparing food too far in advance. Prepare food as close to consumption as possible.
Food cooled too slowly before being refrigerated. Food must be refrigerated within one and a half hours.
Food not reheated enough to kill bacteria. Reheat food until it is piping hot all the way through.
Contaminated food eaten. Do not consume food after its eat-by date, and store correctly.
Food undercooked. Cook food thoroughly - use a temperature probe.
Poultry not thawed properly. Make sure no ice crystals remain.
Cooked food cross-contaminated by raw food. Use separate equipment for raw and cooked food.
Hot food kept warm at less than 63 degrees Celsius. Check food with a temperature probe.
Food handlers passing on infection. Remove jewellery, wear aprons, wash hands, report illnesses, etc.
Left-overs reheated. Use quickly, store below 5 degrees Celsius, reheat thoroughly.


There are 3 types of micro-organism...

  • Moulds
  • Yeasts
  • Bacteria

This table shows the most common types of food poisoning bacteria...

Bacteria: Incubation: Symptoms: Found in: Important points:
Bacillus cereus 1-6 hours Nausea, vomiting, diarrhoea. Cooked rice, especially if kept warm. Cool pasta and rice quickly.
Camploybacter 2-10 days Diarrhoea, abdominal pain. Meat, shellfish, milk, untreated water. Most commonly reported cause of food poisoning.
Clostridium botulinum 12-48 hours Paralysis. Can be fatal. Canned food, especially dish, meat and vegetables. Water and soil. Rare form of poisoning. Bacteria produce spores, which survive high temperatures.
Clostridium perfringens 10-24 hours Diarrhoea, abdominal pain. Raw meat, cooked meat and products. Soil. Very common cause of poisoning. Most active at 45-50 degrees Celsius.
Escherichia coli (E-Coli) 1-2 days Diarrhoea with blood, vomiting Raw meat, untreated milk and dairy products. Drink bottled water when abroad.
Listeria monocytogenes Up to 70 days Flu symptoms, blood poisoning, meningitis. Soft cheeses made with unpasteurised milk, pate, cook/chill foods. Dangerous to pregnant women.
Salmonella 12-48 hours Diarrhoea, fever, vomiting, abdominal pain. Meat, raw eggs, cream, seafood. Babies, the elderly and pregnant women should not eat raw eggs. Poultry must be defrosted well before cooking.
Staphyloccus aureus 1-8 hours Vomiting, diarrhoea. Meat and meat products, eggs. Nose, throat and cuts of food handlers. Personal hygiene is very important.


Enzymes can cause undesirable changes in foods that make them unsightly. This is called browning and is caused by the action of an enzyme called polyphenol oxide in the presence of oxygen. Enzymatic browning can be reduced by:

  1. High temperatures.
  2. Acidic conditions.
  3. Other methods.

Symptoms of food poisoning

  1. Diarrhoea.
  2. Vomiting.
  3. Abdominal pain can be very unpleasant and can even cause hospitalisation, or death, for vulnerable groups such as:
    • Babies.
    • Young children.
    • The elderly.
    • People whose immune systems are damaged.