Ossein is the organic extracellular matrix of bone, which is made of 95% collagen.
In the early 20th century, bones were found to consist of three types of proteins: ossein (collagens), osseomucoid (proteoglycans) and osseoalbuminoid (elastin).
When processed industrially, 1,000 kg of bones yield 300 kg of ossein, which can be rapidly degraded and partially denatured by the prolonged action of slightly acidic boiling water, yielding gelatin.
However, the most popular technique of treating the bone meal is steaming or boiling.
[6] This process requires no acid but much more energy and may also produce tricalcium phosphate.