Food Processing

• Primary processing


  Processing to produce flour from wheat
• Primary processing of wheat to produce flour

  In order for dishes and food products to be made using wheat, it first has to be processed to produce the flour and extract the wheat bran and wheat germ. This is referred to as primary processing.
• Primary processing of wheat to produce flour

  Before the introduction of machinery and the large scale milling of flour, one of the earliest methods used to obtain flour from wheat would involve grinding the grain between two stones called a millstone.

  While millstones are still used in artisan milling, large scale flour milling uses the process of rollers to grind wheat into flour.
• Primary processing of wheat to produce flour

  The large scale modern production of wheat into flour can be summarised as the processes of grinding, separating and regrinding. These steps are repeated to extract the endosperm.
• Primary processing

  The conversion of raw materials into food commodities e.g. milling of wheat grain into flour
• The key processes of wheat milling

  1. Sampling and grading the wheat
  2. Cleaning the wheat
  3. Conditioning the wheat
  4. Gristing the wheat
  5. Grinding the wheat
  6. Processing the flour (streaming)
• Processing the flour after milling

  1. Sifting

  2. Separating

  3. Regrinding the flour several times

  4. Combining different grades of flour to produce different types
• Bleaching agents

  Added to make the flour more white
• Oxidizing agents

  Added to enhance the baking quality of the flour
• Nutrients calcium, iron and the B vitamins (niacin and thiamin) are legally required to be added to all white and brown flours
• Fortification

  Adding required nutrients to flour
• Wholemeal flour already contains these nutrients, although it is lower in calcium
• Baking powder

  Raising agent added to make self-raising flour
• Secondary processing

  Converting primary processed foods into other food products, e.g. flour into biscuits
• Secondary processing of wheat: bread, pasta and breakfast cereals.
• Primary Food Processing

  Primary processing prepares raw foods (straight from being picked, harvested or slaughtered) so they're ready either to be eaten or cooked immediately or used as ingredients to make other food products.
• Fruit, vegetables and meat undergo basic processing

  All food is processed in some way before it reaches our plate. It's important so that food is safe to eat, is easier to transport, doesn't spoil as quickly and looks nice for the consumer.
• Fruit

  Pits (stones) are removed from fruit, e.g. peaches and cherries.

  Fruits are squeezed for fruit juices or dried, e.g. grapes are sun-dried to make raisins.
• Vegetables

  Vegetables are washed with water to remove dirt, insects and chemical sprays.

  Vegetables are sorted into different sizes and shapes and may be peeled.
• Poultry

  Feather and internal organs are removed.

  The wings and legs are tied (trussed) so it cooks evenly.
• Meat

  Some meats (e.g. beef) are hung and dried to make it more tender and improve flavour.

  Meat is chopped, sliced or cut.
• Important B group vitamins are lost when making white flour, so they're added back in.
• The Eatwell Guide recommends wholemeal products as we get the nutritional benefit of the whole grain.
• Wholemeal flour - 100% of the grain is used, nothing is taken out.

  Wholemeal (Brown) flour - about 85% of the grain is used, some of the bran and germ are removed.

  White flour - about 70% of the grain is used (only the endosperm is used)
• Milk is heat treated to kill bacteria

  Milk is heat treated to destroy pathogenic bacteria, but other non-harmful bacteria are also lost.
• Pasteurisation

  Milk is heated quickly to 72C for 15 seconds and then rapidly cooled. There is little change in the taste and nutritional content of pasteurised milk.
• Ultra Heat Treatment (UHT)

  Milk is heated to at least 135C for 1-4 seconds and packed in a sterile container - the milk can last at an ambient temperature for several months. UHT milk has slightly less nutritional value and a slightly different taste than pasteurised milk.
• Sterilisation

  Bottled raw milk goes through a steam chamber at 110C for 10-30 minutes. All bacteria are killed, so it tastes different, and many B group vitamins and vitamin C are lost.
• Microfiltration (MF)

  Bacteria that turn milk sour remain after pasteurisation. Microfiltration forces milk through a membrane which separates the milk from the souring bacteria. This extends the shelf life of the milk and doesn't have much effect on the flavour or nutritional content.