March 17/Rio De Janeiro, Brazil/Journal of Engineering -- "The aging mechanisms of olive oil-lemon juice emulsions were investigated. The emulsions were prepared with xanthan gum where different concentrations of modified starch or maltodextrin were added," scientists in Brazil report.

"Emulsions stability was followed through analysis of the evolution of mean droplet size measured by image analysis during 203 days. All the samples presented phase separation at the end of the studied storage period. The stability results indicate that large droplets' mean diameter were obtained in samples where maltodextrin or only xanthan gum was used. The study of the evolution of the droplet mean diameter with time show that the studied salad dressing ages preferentially through coalescence, although in certain cases molecular diffusion may occur," wrote K.A. Silva and colleagues, Federal University of Rio de Janeiro.

The researchers concluded, "The incorporation of xanthan gum in salad dressing emulsions has a large influence in their rheological behavior."

Silva and colleagues published their study in the Journal of Food Engineering ("Evaluation of Aging Mechanisms of Olive Oil-Lemon Juice Emulsion Through Digital Image Analysis." Journal of Food Engineering, 2010;97(3):335-340).

For more information, contact K.A. Silva, Federal University of Rio de Janeiro, Inst Quim, Center Ciencias Matemat & Nat, BR-21949909 Rio De Janeiro, Brazil.

From the March 29, 2010, Prepared Foods E-dition