title: Stabilization mechanisms of oil-in-water emulsions by Saccharomyces cerevisiae.
abstract: A multiphase system is commonly formed during the oil production by microbial route, which can lead to stable emulsions hindering product recovery. Thus, this study aimed to investigate the mechanisms of emulsion stabilization by the yeast Saccharomyces cerevisiae in order to contribute with processes development of oil production by fermentation. A model system using hexadecane as oil phase and yeast suspension as aqueous phase was used to prepare O/W emulsions. The yeast was subjected to different treatments as inactivation (autoclaving) and washing before to be resuspended in water. The washing water (water from the first washing) and suspension of commercial yeast (active) were also used as aqueous phase. After 24h of preparation, the emulsions separated into three phases: top (cream), intermediate, and bottom phase. The top or cream phase was a concentrated emulsion that kept stable during seven days, except for those prepared from washed yeast that were stable only for a short period of time. Emulsions prepared with washed yeast showed higher cell adhesion to the droplets interface, which implied in a higher amount of yeast into the cream phase in comparison to other formulations. Therefore, yeast cells adhesion plays a role on emulsion stability, but the greater contribution was provided by cell material dispersed into the aqueous phase, regardless of cell viability.
authors.affiliation: Department of Food Engineering (DEA), Faculty of Food Engineering (FEA), University of Campinas (UNICAMP), Rua Monteiro Lobato, 80, Campinas, SP CEP 13083-862, Brazil.
authors.forename: Thais Caldas Paiva
authors.initials: TCP
authors.lastname: Moreira
authors.affiliation: Department of Food Engineering (DEA), Faculty of Food Engineering (FEA), University of Campinas (UNICAMP), Rua Monteiro Lobato, 80, Campinas, SP CEP 13083-862, Brazil.
authors.forename: Vanessa Martins
authors.initials: VM
authors.lastname: da Silva
authors.affiliation: Department of Food Engineering (DEA), Faculty of Food Engineering (FEA), University of Campinas (UNICAMP), Rua Monteiro Lobato, 80, Campinas, SP CEP 13083-862, Brazil.
authors.forename: Andreas Karoly
authors.initials: AK
authors.lastname: Gombert
authors.affiliation: Department of Food Engineering (DEA), Faculty of Food Engineering (FEA), University of Campinas (UNICAMP), Rua Monteiro Lobato, 80, Campinas, SP CEP 13083-862, Brazil. Electronic address: rosiane@unicamp.br.
authors.forename: Rosiane Lopes
authors.initials: RL
authors.lastname: da Cunha
mesh_terms: D000473:Alkanes / Q000737:chemistry*; D004655:Emulsions; D050296:Microbial Viability; D012441:Saccharomyces cerevisiae / Q000737:chemistry* / Q000502:physiology; D013501:Surface-Active Agents / Q000737:chemistry; D013535:Suspensions / Q000737:chemistry; D014783:Viscosity; D014867:Water / Q000737:chemistry*
chemical_list: D000473:Alkanes; D004655:Emulsions; D013501:Surface-Active Agents; D013535:Suspensions; D014867:Water; C007932:n-hexadecane
keywords: Cell viability; Emulsion stability; Yeasts