Microbial production of specialty C4 dicarboxylic acids from maleic anhydride

Maleic acid and its anhydride have been, historically, the main substrate for the production of four-carbon dicarboxylic acids (C4 diacids). Malic, fumaric and tartaric acids are widely used as food accidulants, which improve the flavour profile of new kinds of beverages and foods. In the last decade, the range of their applications greatly expanded in particular in pharmaceutical, chemical and building industries. The compounds can be prepared from maleic acid by chemical or biotechnological processes, or by a combination of these two ways. In this article, the chemical properties, new application trends and the various strategies for the production of all isomers of specialty C4 diacids are reviewed.