Volatile and medium chain fatty acid production from cabbage residues using mixed culture fermentations and in-situ product removal by electrodialysis

Volatile fatty acids (VFA) and medium chain carboxylic acids (MCCAs) are needed in several branches of the chemical industry such as in pharmaceutics, food, and feed, making a biorefinery inspired production that starts from low-grade biomass an interesting alternative to conventional petrochemical processes. In this study, butyric, valeric and caproic acid were produced with a defined co-culture of Megasphaera cerevisiae and Pediococcus pentosaceus by utilizing food waste residue, hydrolyzed cabbage, as the sole carbon source. The developed process was scaled-up to 25 L and coupled with a modified electrodialysis for in-situ product removal to limit the concentrations of accumulating VFAs and MCCAs in the fermentation broth. This process resulted in titers of 10.98 g L-1, 6.19 g L-1 and 0.23 g L-1 of butyric, valeric acid and of caproic acid, respectively, showing that MCCAs and VFAs of growing demand can be produced via valorization of organic residues from waste streams.