05 March 2013


  1. Preservatives are substances added to food to slow down or to prevent the growth of microorganisms so that food can be kept for longer period of time.
  2. Table below shows some examples of preservatives and how they work.
  • Salt
  • sugar
  • Salted fish
  • jam
Salt or sugar draws the water out of the cells of microorganisms and retards the growth of microorganism.
Vinegar Pickled mango Vinegar provides an acidic condotion that inhibits the growth of microorganism.
  • Sodium nitrite or sodium nitrate
  • Benzoic acid or sodium benzoate
  • Sulphur dioxide
  • Burger, sausage and luncheon meat
  • Oyster sauce, tomato sauce, chili sauce and fruit sauce
These preservatives slow down the growth of microorganism

  1. Food containing fats and oils can turn rancid, taht is, the fats and oils are oxidised to become unpleansent-smelling acids, on exposure to the air.
  2. All foodstuff are vulnerable to oxidation. Examples are the browning of apples or potatoes exposed to the air.
  3. Antioxidants are added to food to prevent oxidation that causes rancid fats and brown fruits.
  4. Table below shows some examples of antioxidants.
Butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT) Margarine To retard rancidity in oils.
Ascorbic acid (vitamin C) Fruit juice To preserve the colour of fruit juices
Alpha tocopherol (vitamin E) Vegetables oils To retard rancidity in oils
Sodium citrate Cooked cured meat To stop fats from turning rancid

  1. The use of BHA and BHT has been controversial as it has produced adverse reaction in dogs. Thus, there is a restriction on the amount of this antioxidants used.
  2. Vitamin C and E are among the safest antioxidants known.
  1. Vitamin C inhibits the formation of carcinogenic nitrosimines , stimulate the immune system and protect against chromosome breakage.
  2. Vitamin E neutralises free radical compounds before they can damage cell membranes and helps to reduce the risk of heart disease and cancer.

  1. Flavourings are used to improve the taste of food and restore taste loss due to processing.
  2. Examples of flavouring are sugar, salt, vinegar, monosodium glutamate (MSG), aspartame and synthetic essences such as pentyl ethanoate.
Flavouring Example Function
Monosodium glutamate (MSG)
  • It is the sodium salt of glutamic acid
Frozen food,spice mixes, canned and dry soups, salad dressings and meat or fish based-product To bring out the flavour in many types of food.
  • It is non-sugar sweetener.
  • It is approximately 200 times sweeter than sugar.
  • It has fewer calories than sugar.
  • It is stable when dry or frozen but it breaks down and loses it sweetness over time when stored in liquids at temperature above 30 celcius.
Diet drinks, low-calorie frozen desserts and some soft drinks. To sweeten food
Synthetic essences
  • It contains compaunds belongings to the homologous series of esters.
  • It is cheaper to use these artificial flavours than to use real fruits.
Pentyl ethanoate (banana flavour), ethyl butanoate (pineapple flavour), methyl butanoate (apple flavour) and octyl ethanoate (orange flavour) To produce artificial flavours which resemble natural flavours.

  1. Many food are actually emulsions. Emulsions are either oil droplets suspended in water or water droplets susupended in oil.
  2. Stabilisers are substances which help to prevent an emulsion from separating out.
  3. Stabilisers are used in food which contain oil and water. Examples of these foods are margarine,butter, ice cream and salad cream such as mayonnaise.
  4. Examples of stabilisers are lecithin, mono and di-glycerides of fatty acids.

  1. Thickeners are used to thicken food.
  2. Acacia gum can act as a thickener as well as a stabilisers.
  3. Table below shows some examples of thickeners.
Modified starch Instant soups and puddings.
Pectin Jam
Acacia gum Chewing gum, jelly and wine
Gelatine Yogurt
Xanthan gum Sauce, salad dressing

  1. Food colourings are dyes.
  2. Food processing often leads to a loss of colour.
  3. Food dyes are used to add or restore the colour in food in order to enhance its visual appeal and to maych consumers’s expectations.
  4. Food dyes can be classified into natural and artificial food dyes.
  5. Artificial food dyes are usually used because they are more uniform, less expensive and have brighter colour than natural food dyes.
  6. Many food dyes are azo compounds or triphenyl compounds.
  7. Azo dye have colours such as red, orange and yellow, whereas triphenyl dyes have colours such as blue and green.
  8. Tartrazine, a yellow azo dye, is used in orange drinks,custard powder,sweets and apricot jam. Tartrazine is believed to cause hyperactivity in children.
  9. Brilliant blue FCF, a blue triphenyl dye, is found in beverages, jellies, confections and syrups. It can be combined with tartrazine to produce various shades of green.

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