Isosolids diagram

Figure 8.7. Isosolid diagram of cocoa butter (CB) (Malaysian/Brazilian blend) with anhydrous milk fat (AMF) (Reproduced with permission from Hartel, 1996).

From the 50% solid fat line in the isosolid diagram of physical blends of milk fat and beef tallow, it was evident that there were eutectic and compound interactions but these were absent in interesterified blends with a more complex triacylglycerol composition (Timms, 1979). 

In mixmres of two or more natural fats, as often occurs in processed foods (e.g., milkfat and cocoa butter in chocolate), it is even more difficult to characterize the true phase behavior for crystallization of fats. One approach that has been used to characterize compatibility of fat mixtures is the isosolids diagram (22). SFC melting curves are obtained (by NMR) for various mixmres of the two fats, as seen for cocoa butter and milkfat in Figure 6. Lines of constant SFC for different temperature and composition are calculated and plotted on an isosolids diagram (Figure 7). 

Figure 7. Isosolids diagram for mixtures of anhydrous milkfat (AMF) and cocoa butter (ICB) (4).

Eutectic behavior is seen where the SFC of a mixture falls below the SFC for either of the two individual components, as seen between 30% and 70% milkfat in Figure 7. Isosolids diagrams allow phase compatibility to be studied (4), but they do not provide a thermodynamic measure of driving force for crystallization. Again, because the crystal phase composition may be different at different temperatures (and mixture ratios), isosolids diagrams do not represent true phase diagrams. 

The isosolid diagrams of NIE and CIE POSBO and LCO (Fig. 39) indicate the monotectic solution behavior, which is prevalent in mixed systems consisting of... 

Figure 17.13. Isosolid SFC temperature phase diagrams, as a funetion of blend eomposition, for binary systems eontaining FIMF-CB (A), MMF-CB (B) and AMF-CB (C).

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