How gelatin is made

Gelatin is boiled-down collagen from pig skins and cattle bones, and the cure alone can take weeks.

stations: 7
things upstream: 5
raw sources: 4
steps from the ground: 2

The short version

Gelatin factories take pork skins, cattle bones and split hides, which are by-products of the meat and leather trades. They clean and cure the raw material in acid or alkali for days to weeks, then extract the loosened collagen with hot water in several rounds. The thin broth is filtered, evaporated, sterilized, dried and ground.

Collect meat-trade leftovers

Most gelatin starts as pork skins, pork and cattle bones, or split cattle hides. These are by-products of the meat and leather industries, and fish skins can be used for gelatin that avoids some religious objections.

Goes in
Pigs Cattle hide
Strip fat and minerals

Bones are soaked in dilute acid to dissolve calcium and other salts, and hot water or solvents pull the fat down to under 1 percent. Hides and skins are cut small, washed, de-haired and degreased.

Goes in
Water
Cure in acid or lime

The cleaned material soaks in an acid bath or a lime bath so the tight collagen bonds loosen. Acid suits delicate pig skin and normally takes 10 to 48 hours. Alkali cures last far longer, and the whole curing stage may take several weeks.

Goes in
Quicklime
Extract in hot water

Hot water or dilute acid washes the loosened collagen in several rounds. Early rounds give the strongest gelatin, and later, hotter rounds give weaker gelatin.

Goes in
Water
Filter and clarify

The thin brown broth is filtered through earth and cloth to take out fat, fiber and haze, then deionized to remove salts.
Evaporate and sterilize

The clear solution is thickened in vacuum evaporators and briefly heated at high temperature to sterilize it. Heat, alkaline treatment and filtration are the steps regulators credit with lowering any infectious risk from bovine raw material.
Chill, dry and grind

The concentrate sets to a gel, is chopped into noodles, and is dried on a belt in warm air. The brittle gelatin is then ground and sifted, and batches are blended to a target gel strength.