title: Rhamnolipid emulsifying activity and emulsion stability: pH rules.
abstract: Rhamnolipids have excellent emulsifying power with a variety of hydrocarbons, aromatic compounds and vegetable oils. This paper evaluates the effect of pH ranging from 3 to 9 on the emulsifying activity and stability of rhamnolipids and hydrophobic substrates (benzene, soybean oil and kerosene). Sodium dodecyl sulfate was used as a reference to compare the level of chemical and biological surfactant activity after 24 h (E(24)). The results indicate that pH exerts an influence over emulsion formation and stability. For rhamnolipids, peak emulsifying activity occurred under base conditions for all substrates, with the highest value achieved with kerosene at pH 8. The results of the present study demonstrate that rhamnolipids could replace chemical surfactants, such as SDS, in different industrial fields.
authors: UNESP - Universidade Estadual Paulista, Department of Biochemistry and Microbiology, Institute of Biological Sciences, Av. 24-A, 1515 Bela Vista, CEP 13506-900, Rio Claro, SP, Brazil.
authors: Roberta B
authors: RB
authors: Lovaglio
authors: Francisco José
authors: FJ
authors: dos Santos
authors: Miguel
authors: M
authors: Jafelicci
authors: Jonas
authors: J
authors: Contiero
mesh_terms: D001554:Benzene / Q000737:chemistry; D045703:Emulsifying Agents / Q000737:chemistry*; D004655:Emulsions / Q000737:chemistry*; D006017:Glycolipids / Q000737:chemistry* / Q000378:metabolism; D057927:Hydrophobic and Hydrophilic Interactions; D008958:Models, Molecular; D015394:Molecular Structure; D011550:Pseudomonas aeruginosa / Q000378:metabolism; D012967:Sodium Dodecyl Sulfate / Q000737:chemistry; D013024:Soybean Oil / Q000737:chemistry; D013501:Surface-Active Agents / Q000737:chemistry*
chemical_list: D045703:Emulsifying Agents; D004655:Emulsions; D006017:Glycolipids; D013501:Surface-Active Agents; C418382:rhamnolipid; D012967:Sodium Dodecyl Sulfate; D013024:Soybean Oil; D001554:Benzene