The effect of surface-active substances in chocolate masses
One research project lately concluded at the DIL was titled: “Investigations on the effect of surface-active substances in concentrated lipophilic confectionery suspensions on the example of chocolate mass". The main target of this research project was to determine the precise interactions between solid chocolate particles, e.g. sugar, or cocoa particles and different surface-active substances (SAS) including lecithin, PGPR, sugar ester. In particular, the immobilization of cocoa butter at the solids’ surfaces, which has a significant effect on the processing properties of chocolates with the same fat content, was the subject of intense examination.
Even though a direct influence of the different surface energies of the solid particles on the fat immobilization at these surfaces could not be proven, however, it was shown that the morphology, i.e. the fissures on the surface, clearly affect the interactions with the fat. The addition of surface-active substances in general contributes to a release of fat from the surfaces and a decreasing immobilization of the fat. It was shown that more fat was released when more surface-active substances were present at the solids’ surfaces. The reduced fat immobilization caused by surface-active substances increases the amount of free fat with the result that the equilibrium viscosity of the chocolate mass is lower at the same fat content.
Another interesting result was the influence of surface-active substances present during the grinding process in chocolate production. It showed that PGPR, when added prior to the grinding, results in more favorable rheological properties, i.e. lower yield strengths and lower viscosities. However, lecithin present before or during the grinding has a rather detrimental effect on the rheological properties.
The confectionery industry including SMEs could implement the results from this project within a short time. In particular, the producers and processors of chocolate products will be able to benefit from these results especially for their quality assurance, e.g. the control of the processing properties of the chocolate mass prior to moulding or coating. Furthermore, the results allow a much more precise determination of possible cost advantages for the company because they may save expensive cocoa butter in the chocolate formulations. The understanding of the effects of surface-active substances added to chocolate has been improved and may now be implemented into practice.
Added to that, the moment when SAS was added during the grinding process has also been considered. The results indicate that a more targeted modification of the chocolate's properties by SAS may also be within reach. It seems that in particular a separate addition of individual components from SAS blends (made from PGPR and lecithin) during the fine grinding process may be an alternative to achieve an even better and more precise optimization of the yield strength and the viscosity of the chocolate masses with minimum use of SAS and cocoa butter. The results obtained from investigations on the length of the dry conching process and its effects on the adjustment of the required rheological parameters seem suitable to save costs in chocolate production. A possible reduction in dry conching time may help reduce the energy consumption during the conching process.
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 15217 N).
Contact at DIL for this project is
Dr. Knut Franke
Tel: +49 (0) 5431 183 - 144
E-mail: k.franke@dil-ev.de
For further information, please refer to the project abstract.
