Valorization of Potato-processing Residues for the Production of Lactic Acid

M. Smerilli, M. Neureiter, C. Haas, S. Frühauf and W. Fuchs

Abstract
Every year large amounts of residues accumulate from potato processing. The aim of this study is to develop a process to valorize these residues as feedstock for lactic acid fermentation in a way that is suitable for industrial production. An enzymatic hydrolysate obtained from potato residues (46 % w/w dry mass starch) was used as a substrate in batch and fed-batch fermentations with Lactobacillus casei. Supplementation of yeast extract (3 g L–1) was required to improve productivities. Despite the inhibitory effect exerted by phenolic compounds in the medium, reasonably high lactic acid concentrations (102 g L–1) and yields (92 %) were obtained, with 92 % (L-isomer) optical purity. It was clearly demonstrated that potato residues are suitable as feedstock for large-scale production of technical grade lactic acid and that the developed process is promising for large-scale biorefinery applications.

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Keywords
biorefinery, enzymatic hydrolysis, lactic acid fermentation, Lactobacillus casei, potato residues