Gelatin Production

Appears in
On Food and Cooking

By Harold McGee

Published 2004

  • About
Most manufactured gelatin in the United States and Europe comes from pigskin, though some is also made from cattle skins and from bones. Industrial extraction is far more efficient and gentler on the gelatin chains than kitchen extractions. The pigskins are soaked in dilute acid for 18–24 hours to break the collagen’s cross-linking bonds, and then are extracted in several changes in water, beginning at just 130°F/55°C, and ending around 195°F/90°C. The low-temperature extracts contain the most intact gelatin molecules, produce the strongest gels, and are the lightest in color; higher temperatures damage more gelatin chains and cause a yellow discoloration. The extracts are then filtered, purified, their pH adjusted to 5.5, evaporated, sterilized, and dried into sheets or granules that are 85–90% gelatin, 8–15% water, 1–2% salts, and 1% glucose. Gelatin quality is sometimes indicated by a “Bloom” number (named for Oscar Bloom, inventor of the measuring device), with high numbers (250) indicating high gelling power.