17 Delaying water migration with composite barrier layers.

A. JURGENS, J. M. Maagd, and A. J. ten Dam. TNO Nutrition and Food Research Institute, Dept. of Food Sci. and Technology, Utrechtseweg 48, 3700 AJ Zeist, The Netherlands.

A large variety of composite bakery products exists for which moisture barriers extend shelf life and improve sensory quality even shortly after production. Though solutions are given in literature the many questions from the baking industry point to the fact that acceptable practical solutions are still lacking. Among the most important solutions to be found are a good adhesion to the baked product and the method of application of the barrier. The functional component against moisture migration is a high melting fat. However fats frequently show fracture and adhesion problems. Adhesion can be improved by the application of certain types of hydrocolloids. Crystallization phenomena and viscosity during application of the layer determine the quality of the barrier. During this process step many factors come together such as the actual temperature of product and environment and the porosity of the product. These can be compensated for by a proper selection of the fat composition, hydrocolloid concentration and the temperature of the layer material during application. In the paper these aspects will be discussed.