title: Property control of sophorolipids: influence of fatty acid substrate and blending.
abstract: Sophorolipids (SLs) were synthesized by fed-batch fermentation of Candida bombicola on glucose and either palmitic acid (SL-p), stearic acid (SL-s), oleic acid (SL-o) or linoleic acid (SL-l) and the structural distribution accurately determined by atmospheric pressure chemical ionization-mass spectrometry (APCI-MS). The surfactant properties, including critical micelle concentration (CMC), minimum surface tension (min.ST) and oil-water interfacial tension (IFT) were measured by tensiometry. Minimum STs of 35-36 mN/m were obtained regardless of the substrate while IFTs ranged from 3-5 mN/m with the exception of SL-l, which had an IFT of 7 mN/m. The largest disparity occurred in the CMC values, which ranged from 35 ppm for SL-s to 250 ppm for SL-l. By manually mixing these four SLs in different ratios, it was possible to better control the CMC values without affecting the min.ST or IFT, which will prove beneficial as new applications for SLs are established.
authors.affiliation: Fats, Oils and Animal Coproducts Research Unit, Eastern Regional Research Center, U.S. Department of Agriculture, Agricultural Research Service, Wyndmoor, PA, 19038, USA. Rick.Ashby@ars.usda.gov
authors.forename: Richard D
authors.initials: RD
authors.lastname: Ashby
authors.forename: Daniel K Y
authors.initials: DK
authors.lastname: Solaiman
authors.forename: Thomas A
authors.initials: TA
authors.lastname: Foglia
mesh_terms: D002175:Candida / Q000378:metabolism; D002853:Chromatography, Liquid; D003470:Culture Media; D005285:Fermentation; D005947:Glucose / Q000378:metabolism; D006017:Glycolipids / Q000096:biosynthesis*; D019787:Linoleic Acid / Q000378:metabolism*; D013058:Mass Spectrometry; D008823:Micelles; D019301:Oleic Acid / Q000378:metabolism*; D019308:Palmitic Acid / Q000378:metabolism*; D013229:Stearic Acids / Q000378:metabolism*; D013379:Substrate Specificity; D013500:Surface Tension; D013501:Surface-Active Agents / Q000737:chemistry / Q000302:isolation & purification
chemical_list: D003470:Culture Media; D006017:Glycolipids; D008823:Micelles; D013229:Stearic Acids; D013501:Surface-Active Agents; D019301:Oleic Acid; D019308:Palmitic Acid; D019787:Linoleic Acid; D005947:Glucose