Production of propionic acid

Abstract

Propionic acid and its salts are widely used in industry and especially in the food industry as antifungal agents. The estimated world production in 1992 was about 100 000 tonnes. A large part of this production is by petrochemical routes. Nevertheless, fermentation processes have been described since 1923. The increasing consumer demand for biological products and the more efficient performance of new fermentation processes have revived researcher and industrial interest for a new investigation of biological propionic acid production. From the low productivity of batch processes (0.03 g l-1 h-1), performance has rapidly increased to 2 to 14 g l-1 h-1. This increase results from the emergence of high density cell bioreactor technology. These bioreactors make it possible to concentrate large amounts of cells within the system during continuous fermentation and to reduce the cell inhibition effect of organic acid accumulation in the medium. Moreover, the use of glycerol as the principal carbon source enables propionic acid to be produced without acetic acid. The increased efficiency of membrane processes, such as electro-electrodialysis and electrodialysis with bipolar membrane, has considerably facilitated the recovery and purification steps from fermented media. The increased fermentation volumetric productivity and downstream processing performance has led to an economic industrial biological propionic acid production. © 1995 Elsevier/NRA.