ORIGINAL PAPER Analytical characterization of mannosylerythritol lipid biosurfactants produced by biosynthesis based on feedstock sources from the agrofood industry Matthias Onghena & Tinne Geens & Eliane Goossens & Marc Wijnants & Yolanda Pico & Hugo Neels & Adrian Covaci & Filip Lemiere Received: 11 December 2010 /Revised: 21 January 2011 /Accepted: 27 January 2011 /Published online: 12 February 2011 # Springer-Verlag 2011 Abstract Mannosylerythritol lipids (MELs) are currently one of the most promising biosurfactants because of their multifunctional applications and good biodegradability. Depending on the yeast strain and the feedstock used for the fermentation process, structural variations in the MELs obtained occur. Therefore, MELs produced by Pseudozyma aphidis DSMZ 70725 with a soybean oil feedstock were characterized by chromatography and mass spectrometry (MS). Column chromatography with silica provided frac- tionation of the different types of MEL. High-performance liquid chromatography combined with MS was employed for the analysis of the MEL fractions and crude mixtures. A characteristic MS pattern for the MELs was obtained and indications of the presence of new MEL homologues, showing the incorporation of longer and more unsaturated fatty acid chains than previously reported, were given. Gas chromatography–MS analysis confirmed the presence of such unsaturated fatty acid chains in the MELs, demon- strating the incorporation of fatty acids with lengths ranging from C 8 to C 14 and with up to two unsaturations per chain. The incorporation of C 16 and C 18 fatty acid chains requires further investigation. MS/MS data allowed the unambigu- ous identification of the fatty acids present in the MELs. The product ion spectra also revealed the presence of a new isomeric class of MELs, bearing an acetyl group on the erythritol moiety. Keywords Mannosylerythritol lipids . Mass spectrometry . Fatty acids . Liquid chromatography . Gas chromatography Introduction Conventional washing and cleaning products, such as ionic (e.g., sodium lauryl sulfate) or nonionic (e.g., pentaerythrityl palmitate) detergents, are mainly derived from petrochemical (fossil) raw materials and are produced by chemical means. Use of these surfactants has recently been under strong pressure because of the increased public concern regarding their low degradability, accumulation in the environment, and often high (eco) toxicity. In addition, petrochemical resources are heading towards exhaustion [1]. These economical and ecological aspects explain the growing interest in the investigation of “greener” biosurfactants [2, 3]. Fully environmentally friendly detergents do not exist, even though criteria such Footnote: Published in the special issue Advances in Analytical Separations with Guest Editors Yolanda Pico and Joan O. Grimalt. M. Onghena : E. Goossens : M. Wijnants Department of Industrial Sciences and Technology, Karel de Grote University College, Research Group Industrial Biotechnology, Salesianenlaan 30, 2660 Hoboken, Antwerp, Belgium T. Geens : H. Neels : A. Covaci (*) Toxicological Centre, Department of Pharmaceutical Sciences, University of Antwerp, Universiteitsplein 1, 2610 Wilrijk, Antwerp, Belgium e-mail: adrian.covaci@ua.ac.be Y. Pico Department of Pharmacy, University of Valencia, Avenida Vicent Andres Estelles s/n, 46100 Burjassot, Valencia, Spain F. Lemiere Nucleoside Research and Mass Spectrometry Unit, Department of Chemistry & CeProMa, University of Antwerp, Groenenborgerlaan 171, 2020 Antwerp, Belgium Anal Bioanal Chem (2011) 400:1263–1275 DOI 10.1007/s00216-011-4741-9