A kinetic analysis of crystallization of a milk fat model system

摘要: Abstract Crystallization behavior of milk fat, pure triacylglycerol (TAG) fraction fat and three blends 30, 40 50% high-melting (MDP=47.5°C) in low-melting (MDP=16.5°C) were studied by turbidimetry nuclear magnetic resonance (NMR). Nucleation was similar for these systems. In all cases, curves log induction time vs. temperature continuous, which means that when samples crystallized from the melt, only one polymorphic form obtained at temperatures. X-ray patterns verified formation β′ form. The calculated activation free energies nucleation quite low, but close to ones published other fats systems, such as hydrogenated sunflower oil. Only a low supercooling needed start crystallization. When isothermal crystallization NMR, same also found samples. For (crystallization temperatures above 25°C), had sigmoidal shapes with period beginning. high (temperature below no times observed occurred rapidly. An intermediate plateau SFC clearly visible curves. step this decreased steadily both rate height Tc increased. interpreted Avrami kinetic model, parameters Kn n calculated. best fit setting 3. was, on average, 10 lower 25°C.