Small acids (e.g. malic acid, fumaric acid, propionic acid, succinic acid, etc.) are essential in various industries, serving as chemical precursors, antimicrobials and acidulants in the cosmetic, pharmaceutical, food and chemical sectors. These acids are promising candidates for production from biobased raw materials via fermentation, given their well-established biosynthetic pathways. The production of such acids requires a strict pH buffering system leading to accumulation of salts. In addition, acids are usually water soluble and therefore difficult to separate from the fermentation broth.  

To mitigate this issue, the conventional approach is to neutralize the organic acids by adding a base into the fermentation medium, converting the acids into their corresponding salts, causing them to precipitate from the broth. However, this process leads to large waste streams of a mixture of salts, both desired and undesirable that require energy-intensive separations and processes to recycle. An alternative approach involves in-situ extraction of the organic acids using an organic solvent such as ethyl acetate. However, the efficiency of this process depends on the concentration and partition coefficient of the organic acid, often requiring high solvent flows, which increase solvent use and operational costs.