”The improvement of the storage stability of chocolate products with aqueous, non-alcoholic fillings based on O/W emulsions” was the title of a 30 months research project the DIL conducted in cooperation with the Fraunhofer Institute for Process Engineering and Packaging IVV in Freising, Germany. Main objective was the close examination of the processes that take place in the layer between the chocolate shell and an oil-in-water emulsion chocolate truffle type filling. Within the scope of the project, the main influencing factors on quality deviations during storage of these products and possible control parameters should be determined.

In this type of filling, the concentration related mass exchange processes between the chocolate shell and the filling, which are finally responsible for the development of the quality during storage, are governed by the binding of the water and the migration of the inner oil phase into the chocolate shell. The structure of the chocolate shell, e.g. its micro pores and ingredients (emulsifiers) play an important role in the migration of substances from the fillings. The introduction and stabilization of the water in the fillings of these products is a very interesting aspect in new product development conducted at the manufacturers of chocolate products.

One key result from the project was the formulation of scientific principles according to which chocolate products with O/W emulsion fillings and an improve storage stability can be produced. For that, model systems (specifically composed chocolate disks) as well as industrially produced chocolate shells were used to investigate a large spectrum of recipes and production processes relevant for practical applications.

It was shown that the binding of the water to the macro molecules can be increased either by a more intense introduction of energy (microwave) or by conventional heating in the presence of saccharides. This way the migration of the water into the chocolate shell can be reduced compared to other fillings with the same moisture content. Added to that, it was proven that the mobility of the water in the filling can be restricted through smaller oil droplets in combination with a high specific interface in the emulsion. The same effect can be achieved by increasing the oil content in the filling.

In terms of chocolate, clear dependencies between the type of emulsifier in the chocolate and the water absorption were found. Obviously the migration of substances decreases when emulsifiers with high HLB values are used. The examination of the structure with a scanning electron microscope and the analysis of the sugar spectrum in the fillings prove that even water-soluble substances (in particular sucrose) migrate from the chocolate into the filling.

In the tests with industrially produced chocolate it was confirmed that a migration of oil from the filling into the chocolate was not detectable. Regarding the influence of the type of chocolate, it was shown that in milk and dark chocolates a moisture migration took place during the storage period while chocolate with a higher content in cocoa or fat is more resistant against water diffusion.

The project was supported within the scope of the “program for promoting joint industrial research (IGF)” by the Federal Ministry for Economy and technology (via AiF) through the Association Energy and Environment (VEU) (AiF project no 14947 N).

For more information about the project, please contact

Dr. Ute Bindrich       
Phone: +49 (0) 5431 183 - 130               
E-mail: u.bindrich@dil-ev.de

Dr. Knut Franke
Phone: +49 (0) 5431 183 - 144
E-mail: k.franke@dil-ev.de