Citric acid
The most used food acid, fermented from sugar or glucose by a mould; China makes most of the world's supply and sets the price.
Bio-based chemicals · Fermentation products · No. 109
- Single chemical
- Feedstock: Crops and biomass
- about 2.5-3 Mt a year (2025, indicative; no official world tonnage published)
- HS 291814
The tang in your fizzy drink comes not from lemons but from a black mould fed on maize sugar.
Chart: Illustration: Citric acid
Where it comes from
Chart: Map of where it comes from
A mould, Aspergillus niger, ferments glucose or molasses in giant tanks for 5-10 days, leaving about 1 t of gypsum per tonne of acid.
Three things to know
- Pfizer scaled up mould fermentation in the 1920s and 1930s, ending reliance on Italian lemons.
- Each tonne of citric acid needs roughly 1.1-1.3 t of sugar or glucose.
- The EU and US have held anti-dumping duties on Chinese citric acid since 2008-2009, splitting the world into price zones.
The journey
- 1 CropMaize, cassava or cane and beet molasses
- 2 Sugar prepStarch hydrolysed to glucose, molasses diluted
- 3 FermentationAspergillus niger works for 5-10 days
- 4 RecoveryLime and sulphuric acid, leaving gypsum
- 5 CrystalsSold as powder or citrate salts