Fruity flavors from waste: A novel process to upgrade crude glycerol to ethyl valerate

Ramon Ganigué, Pieter Naert, Pieter Candry, Jonas de Smedt, Christian V. Stevens, Korneel Rabaey

Research output: Contribution to journalArticlepeer-review

16 Scopus citations


Valeric acid and its ester derivatives are chemical compounds with a high industrial interest. Here we report a new approach to produce them from crude glycerol, by combining propionic acid fermentation with chain elongation. Propionic acid was produced by Propionibacterium acidipropionici (8.49 ± 1.40 g·L−1). In the subsequent mixed population chain elongation, valeric acid was the dominant product (5.3 ± 0.69 g·L−1) of the chain elongation process. Residual glycerol negatively impacted the selectivity of mixed culture chain elongation towards valeric acid, whereas this was unaffected when Clostridium kluyveri was used as bio-catalyst. Valeric acid could be selectively isolated and upgraded to ethyl valerate by using dodecane as extractant and medium for esterification, whereas shorter-chain carboxylic acids could be recovered by using a 10 wt% solution of trioctylphosphine oxide (TOPO) in dodecane. Overall, our work shows that the combined fermentation, electrochemistry and homogeneous catalysis enables fine chemical production from side streams.
Original languageEnglish (US)
Pages (from-to)121574
JournalBioresource Technology
StatePublished - May 28 2019
Externally publishedYes

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