title: Organogel-emulsions with mixtures of β-sitosterol and γ-oryzanol: influence of water activity and type of oil phase on gelling capability.
abstract: In this study, water-in-oil emulsions were prepared from water containing different salt concentrations dispersed in an oil phase containing a mixture of β-sitosterol and γ-oryzanol. In pure oil, the β-sitosterol and γ-oryzanol molecules self-assemble into tubular microstructures to produce a firm organogel. However, in the emulsion, the water molecules bind to the β-sitosterol molecules, forming monohydrate crystals that hinder the formation of the tubules and resulting in a weaker emulsion-gel. Addition of salt to the water phase decreases the water activity, thereby suppressing the formation of sitosterol monohydrate crystals even after prolonged storage times (∼1 year). When the emulsions were prepared with less polar oils, the tubular microstructure was promoted, which significantly increased the firmness of the emulsion-gel. The main conclusion of this study is that the formation of oryzanol and sitosterol tubular microstructure in the emulsion can be promoted by reducing the water activity and/or by using oils of low polarity.
authors.affiliation: Laboratory of Physics and Physical Chemistry of Foods, Department of Agrotechnology and Food Sciences, Wageningen University, Wageningen, The Netherlands. hassan.sawalha@wur.nl
authors.forename: Hassan
authors.initials: H
authors.lastname: Sawalha
authors.forename: Ruud
authors.initials: R
authors.lastname: den Adel
authors.forename: Paul
authors.initials: P
authors.lastname: Venema
authors.forename: Arjen
authors.initials: A
authors.lastname: Bot
authors.forename: Eckhard
authors.initials: E
authors.lastname: Flöter
authors.forename: Erik
authors.initials: E
authors.lastname: van der Linden
mesh_terms: D004655:Emulsions / Q000737:chemistry; D010666:Phenylpropionates / Q000737:chemistry*; D010938:Plant Oils / Q000737:chemistry*; D012855:Sitosterols / Q000737:chemistry*; D000074242:Sunflower Oil; D014867:Water / Q000737:chemistry*
chemical_list: D004655:Emulsions; D010666:Phenylpropionates; D010938:Plant Oils; D012855:Sitosterols; D000074242:Sunflower Oil; D014867:Water; C025473:gamma-sitosterol; C013172:gamma-oryzanol