Polymorphic structure
The polymorphic form of MKF crystallized at 18 °C without and with the
HIU application is shown in Fig. 4. Without the application of HIU, MKF
crystallized into β′ structure at 15 and 30 min of crystallization with
a diffraction peak in wide-angle scattering at 4.14 Å. At 60 min, the
sample showed the coexistence of β′ and β (4.6 Å) polymorphs, indicating
that the β′→β transition was ongoing between 30 and 60 min of
crystallization time. With the application of HIU (70% amplitude), the
sample solidified into β′ polymorph at 15 min and at 30 min it was
already in the mixture of β′ and β polymorphs. At 60 min, β form was the
dominant polymorph. It can be seen from the results that the β′→β
transformation started to occur sooner in thesample that crystallized
with HIU. HIU was found to accelerate β′→β transition in CB (Higaki et
al., 2001), promote the formation of β′ crystal polymorph in anhydrous
milk fat (Frydenberg et al., 2013) and promote β crystal formation for
tripalmitin and trilaurin (Ueno et al., 2003). Acceleration of
crystallization is of great significance to the food industry as this
could shorten the processing time and hence reduce processing costs.
(Frydenberg et al., 2013). These results correlate well with the results
obtained by DSC.