Sugaring-out extraction coupled with fermentation of lactic acid

• Sugaring-out extraction was first proposed in lactic acid separation.
• Sugaring-out extraction coupling fermentation was successfully applied to lactic acid production.
• 84.3% lactic acid was recovered using sugaring-out extraction system composed of 12% (w/w) glucose and 40% (w/w) isopropanol.
• 91.1% lactic acid was achieved by coupling of fermentation and sugaring-out extraction.

Sugaring-out extraction as a novel phase separation for sugar-based chemicals was postulated to extract lactic acid from the fermentation broth by means of sugars and organic solvents. From the different sugaring-out extraction systems investigated, the isopropanol/glucose system was found to be more favorable. The partition coefficient (1.39) and recovery (84.27%) of lactic acid were obtained by a system consisting of 12% (w/w) glucose and 40% (w/w) isopropanol. The glucose-rich bottom phase can be utilized to produce lactic acid after recovery of isopropanol. The experimental results were comparable with the normal fermentation, e.g. the yield of lactic acid to glucose being 91.1% vs. 94.0%. This provides a novel approach to integrate sugaring-out extraction into fermentation for production of sugar-based chemicals.

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