Fumaric acid

Tartness agent: Powdered drinks, pudding, pie fillings, gelatin desserts.
A solid at room temperature, inexpensive, and highly acidic, fumaric acid is the ideal source of tartness and acidity in dry food products. However, it dissolves slowly in cold water, a drawback cured by adding DIOCTYL SODIUM SULFOSUCCINATE (DSS), a detergent-like additive that appears to be safe.