Page "Gelatin" Paragraph 15

If the physical material that will be used in production is derived from bones, dilute acid solutions are used to remove calcium and similar salts.

Hot water or several solvents may be used for de-greasing.

Maximum fat content of the material should not exceed 1 % before the main extraction step.

If the raw material is hides and skin, size reduction, washing, removing hair from the hides, and de-greasing are the most important pretreatments used to make the hides and skins ready for the main extraction step.

Raw material preparation for extraction is done by three different methods: acid, alkali, and enzymatic treatments.

Acid treatment is especially suitable for less fully crosslinked materials such as pig skin collagen.

Pig skin collagen is less complex than the collagen found in bovine hides.

Acid treatment is faster than alkali treatment and normally requires 10 to 48 hours.

Alkali treatment is suitable for more complex collagen, e. g., the collagen found in bovine hides.

This process requires longer time, normally several weeks.

The purpose of the alkali treatment is to destroy certain chemical crosslinkages still present in collagen.

The gelatin obtained from acid treated raw material has been called type-A gelatin, and the gelatin obtained from alkali treated raw material is referred to as type-B gelatin.

Enzymatic treatments used for preparing raw material for the main extraction step are relatively new.

Enzymatic treatments have some advantages in contrast to alkali treatment.

Time required for enzymatic treatment is short, the yield is almost 100 % in enzymatic treatment, the purity is also higher, and the physical properties of the final gelatin product are better.