How vitamin C tablets are made

Industrial vitamin C is built from plain glucose, with bacteria doing one of the hardest steps.

stations: 7
things upstream: 22
raw sources: 8
steps from the ground: 7

The short version

Industrial vitamin C starts with glucose from corn starch. Hydrogen turns it into sorbitol, bacteria convert the sorbitol into a sugar called sorbose, and further chemical steps turn that into ascorbic acid. The crystals are purified, dried, blended with binders and pressed into tablets.

Break the starch into glucose

Corn starch is treated with enzymes until it falls apart into glucose, a simple sugar.

Goes in
Corn starch Water
Hydrogenate the glucose

In a pressure vessel, hydrogen over a nickel catalyst turns glucose into sorbitol, a sugar alcohol.

Goes in
Hydrogen
Ferment the sorbitol

Acetobacter bacteria oxidize the sorbitol into sorbose. The microbes do this step because they can get the shape of the molecule right, which chemistry alone struggles to do.

Goes in
Air
Convert to ascorbic acid

Chemical steps then oxidize sorbose and close it into a ring, giving ascorbic acid. The classic route takes five steps, and newer routes shorten it.
Crystallize and dry

The acid is crystallized out, washed and dried into a pure white powder.
Blend and press

Powder is blended with a binder and a sweetener, then pressed into tablets by a rotary press.

Goes in
Sugar
Count and bottle

Tablets are counted by machine into bottles with a desiccant and sealed.

Goes in
Plastic bottle

End of the lineVitamin C tablet Next it goes into flour.

Worth repeating

The Reichstein process, devised in 1933, combines chemistry and microbial steps to make ascorbic acid from glucose.
Reichstein's process was patented and sold to Hoffmann-La Roche in 1934.
In 1988, Genencor International and Eastman Chemical announced a shorter biotech route that cut the five steps to two.