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.