Extracting long‐chain fatty acids from a fermentation medium

Several solvents were evaluated for extracting free long‐chain FA (LCFA) from a fermentation medium. Chloroform, chloroform/methanol (1∶1), hexane, and hexane/methyl tert ‐butyl ether (MTBE) (1∶1) were evaluated as alternative extraction solvents. Parameters considered for optimizing LCFA recoveries included pH and ionic strength. Maximal LCFA recoveries were obtained by adding 2 mL of the hexane/MTBE (1∶1) solvent mixture, 80 μL of 50% H 2 SO 4 , and 0.05 g NaCl to 1 mL of the aqueous sample and mixing for 15 min at 200 rpm. This method quantified saturated LCFA [capric acid (C 10∶0 ) to stearic acid (C 18∶0 )] and unsaturated LCFA with 18 carbons [linoleic acid (C 18∶2 ) and oleic acid (C 18∶1 )] with a 98 to 100% recovery. Caproic (C 6∶0 ) and caprylic (C 8∶0 ) acids were characterized by 27 and 76% recoveries, respectively.