Formulation of Conjugated Linoleic Acid Microemulsion Using Mixed Nonionic Surfactants

Abstract

A novel class of conjugated linoleic acid (CLA)-in-water microemulsion based on Tween80, EL-35, ethanol, and n-octanol was investigated as potential food delivery systems. The influences of pH on the microemulsion region were considered. The microemulsion structural transition was divided into water-in-oil (W/O), bicontionuous, and oil-in-water (O/W) microemulsion by conductivity and viscosity method. The microemulsion size and polydispersity were determined by dynamic light scattering (DLS). The size of O/W microemulsion droplets depends strongly on the contents of surfactants and CLA, and the diameter ranges from 22.1 to 30.7 nm and from 18.3 to 32.8 nm, respectively. All samples keep a remarkable stability in the experiments of 30 days. The stability of CLA in microemulsion and ethanol solution was determined by ultraviolet-visible spectrophotometry, the results revealed that the stability of the CLA in the microemulsion was increased remarkably.

Keywords:

• Conjugated linoleic acid
• microemulsion
• phase transition
• stability

Support of this work by the Natural Science Fund of China (20573048, 20676051) and the Foundation of Shanghai (07DZ19508, 07DZ05019) is gratefully acknowledged.

Notes

^a Saa is the mixture of surfactants and cosurfactants in fixed mass ratio.

^b R _h and PDI are hydrodynamic radius and polydispersity index, respectively.