Innovation in sodium erythorbate production: the use of membrane-reactors.

Isoascorbic or erythorbic acid is a stereoisomer of ascorbic acid acting as a preservative against oxidation and decoloration, recently approved for food use also in the European Market. Actually erythorbate is produced by means of a complex and long process after bio-fermentation of dextrose. In order to simplify and improve this process a membrane system was conceived able to induce acid 2-ketogluconic diffusion from fermentation broth directly into methanol where it esterificates. Acid 2-ketogluconic methyl ester is the intermediate for erythorbic acid. The principal problem was to perfectly separate water from methanol to avoid saponification instead of esterification.