Fumaric acid is produced industrially by the catalytic isomerization of maleic acid or by the oxidation of furfural. This yields a white, odorless, crystalline powder. It is the strongest-tasting food acid on a weight basis, approximately 1.5 times as sour as citric acid.
This makes it one of the most cost-effective acidulants available. Fumaric acid has very low water solubility (0.63 g/100ml at 25°C), which limits its use in clear beverage applications but offers advantages in dry mixes and confectionery where slow dissolution and controlled acid release are desired. Its extremely low hygroscopicity provides outstanding shelf stability in powdered and granulated food products. Fumaric acid also functions as a preservative and antimicrobial agent by lowering pH below the growth threshold of many spoilage organisms.
