Abattoir Practices and Animal Products Technology

SELECTION OF BONES

• This process involves selection of mainly six long bones-femur, tibia, metatarsus, humerus, radius and ulna, metacarpus, etc.
• Cutting
  • Only thighbones (tibia), buttock bones (femur), flat (meta-tarsus), and round (meta-carpus) skin bones, blade (Radius and ulna) and cannon (humerus) bones should be used.
  • The first is to saw of the knuckles and kneecaps with a power driven circular saw.
  • The cutting is done through the line of the nerve hole, the aim being to expose the marrow to the direct action of hot water.
• Heating
  • A tank provided with perforated steam coils, which allows the injection of live steam, can be used.
  • When steam is unavailable cooking can be done in open tank. The tank is filled with cold water and then charged with bones.
  • Then the water is heated gradually.
  • The temperature should not exceed 87.8°C (190°F) for about 6 hours, which is sufficient to melt the fat and loosen all the adhering meat.
  • The bones should not be boiled nor did the bones put into boiling water.
• Cooking
  • Cooking may be taken for about 10 hours.
  • After cooking the tank is allowed to cool.
  • The fat will rise to the top and can be skimmed off.
  • The bones are washed and then dried.
  • Then the dried bones are crushed.
  • These crushed bones are dispatched for preparation of gelatine.
  • Gelatine is extracted under carefully controlled pressure.
  • A strong solution is run off from the digester.
• Washing
  • After removal of fat, the bones are washed with warm water.
• Drying
  • These bones are dried in sun on wire netting.
  • In wet weather, drying is done in hot room.
• Crushing
  • The bones are crushed by a simple stone crusher to a size ranging from 1-2 cm cubes.
  • Crushed bone pieces, which pass through 0.2 cm mesh, are considered bone meal.