Organogel-emulsions with mixtures of β-sitosterol and γ-oryzanol: influence of water activity and type of oil phase on gelling capability

J Agric Food Chem. 2012 Apr 4;60(13):3462-70. doi: 10.1021/jf300313f. Epub 2012 Mar 22.

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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Emulsions / chemistry
  • Phenylpropionates / chemistry*
  • Plant Oils / chemistry*
  • Sitosterols / chemistry*
  • Sunflower Oil
  • Water / chemistry*

Substances

  • Emulsions
  • Phenylpropionates
  • Plant Oils
  • Sitosterols
  • Sunflower Oil
  • Water
  • gamma-sitosterol
  • gamma-oryzanol