PHYSICAL BEHAVIOR OF BINARY-MIXTURES OF C ACAO BUTTER AND MILK FATS, USING PULSED NUCLEAR-MAGNETIC-RESONANCE - ISOSOLID AND KINETIC CRYSTALLIZATION CURVES

The cocoa butter (BC) / anhydrous milk fat (MGLA) isosolids diagrams w ere obtained by pulsed nuclear magnetic resonancy (NMR). The study of the crystallization curves of these mixtures was followed also by puls ed NMR. Two different BCs with extreme physical properties were mixed with one MGLA and one fractionated MGLA with high melting point (HPF). The isosolid diagrams were deduced from the NMR measurements (solid c ontent versus temperature) which were made immediately after tempering (precrystallization) and after one month of shelf-life al 20 degrees C. Crystallization curves (solids content versus time) were made from samples freshly tempered and maintained at a temperature such that cry stals seeds were still present in the liquid phase. Each sample were p laced in the NMR cell thermostatically regulated at 10 degrees C. Unte mpered samples were also examined. It was shown that the great differe nces observed between the two BCs influence the behaviour of the mixtu res of these BCs with MGLA. The melting properties of the BC are more variable than the melting properties of the MGLA. These results requir e modifications of the tempering conditions. A sample of milk chocolat e was examined (curves of crystallization) during the tempering proces s. The different curves obtained show that the tempering process could be monitored by pulsed RMN.