| Popis: |
Polymorphism and growth behavior of blends of a high-melting fraction of milk fat (HMF) and sunflower oil (SFO) formulated with and without the addition of sucrose esters (SE) P-170, P-1670, and S-170 were studied by pulsed 1H NMR spectroscopy, X-ray diffraction, and polarized light microscopy. The effect of SE on the solid content maximum (S max) or crystallization rate was observed only at low supercooling (values of ΔT below 15°C). The Avrami k n decreased as n values increased, indicating that SE inhibited growth and impeded nucleation. Addition of SFO modified the polymorphic behavior of milk fat, most likely owing to the increase in the C54 fraction (mostly 18∶1 cis) in crystals composition. P-170 and S-170 modified the polymorphic behavior of HMF when it crystallized in the α-form or in blends with up to 40% SFO at all crystallization temperatures (T c ) selected. Addition of P-170 and S-170 favored crystallization in the β′-form, and the appearance of the β-form was delayed. P-1670 had no effect on polymorphism. When HMF and the blends were crystallized under dynamic conditions, addition of P-170 and S-170 markedly decreased crystal sizes. P-1670, however, showed no effect on microstructure. |
