Engineering interfacial properties by anionic surfactant-chitosan complexes to improve stability of oil-in-water emulsions

Food Funct. 2012 Mar;3(3):312-9. doi: 10.1039/c2fo10197a. Epub 2012 Feb 2.

Abstract

Oil-in-water emulsions (10% w/w n-tetradecane) were prepared at pH = 5.7 by using, as surface active agents, electrostatically formed complexes of sodium stearoyl lactylate (SSL) at a concentration of 0.4% (w/w) and chitosan (CH) in a concentration range between 0 and 0.48% w/w. The use of complexes in emulsions with a low concentration of CH (<0.24% w/w) resulted in highly flocculated systems; instead, with increased level of CH, the emulsions had a smaller average droplet size and exhibited greater stability during storage. Emulsions stabilised by SSL/CH complexes showed non-Newtonian flow behavior with pronounced shear thinning. Among all formulations studied none showed a gel-like behavior since in all cases the G' (storage modulus) was lower that G'' (loss modulus). Adsorption kinetics of pure SSL and SSL/CH complexes to the oil/water interfaces were evaluated using an automated drop tensiometer (ADT). Even though complexation of SSL with CH resulted in a delay of the adsorption of the surface active species at the oil/water interface, the inclusion of the polysaccharide resulted in substantially improved interfacial properties as indicated by a significant increase of the dilatational modulus. Furthermore, the enhanced interfacial properties of the emulsion droplets resulted in improved stability against freeze-thaw cycling. The results of this study may facilitate the development of frozen food products such as desserts with an ameliorated stability and favorable sensorial characteristics.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adsorption
  • Chitosan / chemistry*
  • Emulsions / chemistry*
  • Kinetics
  • Particle Size
  • Surface-Active Agents / chemistry*

Substances

  • Emulsions
  • Surface-Active Agents
  • Chitosan