The difference between cocoa butter and Salatrim (R) lies in the microstructure of the fat crystal network

The solid fat content of Salatrim(R) at 22 degrees C is 9% higher than that of cocoa butter; however, its storage modulus, G' (1 Hz), or solid-like ch aracter, is one order of magnitude lower (2.5 MPa vs. 52 MPa). This differe nce may be explained by structural differences in the microstructure of the fat crystal network of the respective fat systems. Polarized right microgr aphs of these two confectionery fats show that cocoa butter forms a fat cry stal network characterized by discrete crystalline particles which aggregat e to larger microstructures which then form a three-dimensional network, wh ile Salatrim(R)'s network is composed of randomly arranged noncrystalline, translucent platelets. Rheological measurements on both fat networks yielde d fractal dimensions of 2.37 for cocoa butter and 2.90 for Salatrim(R). Ima ge analysis of the microstructure of cocoa butter yielded a fractal dimensi on of 2.31; however, the microstructure of Salatrim(R) does not lend itself to fractal analysis via image analysis. It was observed that the microstru cture of Salatrim(R) is random instead of fractal. The proposition is made that the macroscopic mechanical properties of Salatrim(R) are related to th e mechanical properties of the platelets that make up the network and the n ature of the links between the platelets. Furthermore, the random spatial d istribution of the platelets does not provide an indication of the strength of the network. For cocoa butter, the macroscopic mechanical properties ar e integrally related to the fractal spatial distribution of the solid mass in the network, the nature of the links between the microstructures, and th e strength of the microstructures.