For the production of halal gelatin, both ossein and cattle hide pieces
are subjected to lengthy treatment with an alkali, usually lime and water,
at ambient temperature. Depending on previous treatment, nature of the material, size of the pieces, and exact temperature, liming usually takes
8 to 12 weeks. The process is controlled by the degree of alkalinity of
the lime liquor as determined by titration with acid, or by making test
extractions. Ossein usually requires more liming time than cattle hide
does. Additional lime is added to maintain an excess, thereby compensating
for any that is consumed. The material is then thoroughly washed
with cold water to remove excess lime, its pH adjusted with acid, and it
is extracted with hot water to recover the soluble gelatin.