Abattoir Practices and Animal Products Technology

BY-PRODUCTS OF BONES

• Bones contain 33 to 36% of organic substance, bone collagen or ossein, which is the mother substance for gelatine and glue.
• Gelatine
  • Gelatine can be obtained by boiling ossein or by boiling degraded bones in water acidified with Hydrochloric acid, which separates the gelatinous substances.
  • It is a derived protein of albuminoidal class, which has both – edible and inedible (technical) uses.
  • Edible gelatine is manufactured from fresh bones obtained from slaughtered and inspected animals under strict hygienic conditions.
  • Pure gelatine is an amorphous and transparent substance devoid of any colour, taste and smell.
  • It is brittle when dry, softens on heating and then decomposes with burnt hair smell.
  • It swells in cold water absorbing 5 to 10 times its weight and dissolves on warming upto 30oC.
• Glue
  • Glue is the inferior gelatine and is obtained in the same manner as gelatine.
  • It is low-grade gelatine with comparatively dark colour and has only inedible uses.
  • Chemically there is no difference between gelatine and glue.
  • Glue is used as an important adhesive in plywood, furniture, sand paper, gummed tape, etc.
• Ossein
  • Ossein is obtained by breaking the bones in weak acids, which dissolves the mineral components leaving the organic matter.
• Bones may by collected from
• Abattoirs where large quantities of bones are available.
• In the field where bones may be collected from eating houses, refuse dumps or from carcasses.
• Skull and jawbones are non-gelatine-yielding bones.
• Gelatine manufacturers grade the bones in five different groups as Grade I, II, III, IV and V.
• Only long bones are selected not the flat bones.