Effects of Polyglycerine Fatty Acid Esters Having Different Fatty Acid Moieties on Crystallization of Palm Stearin

We studied the effects of adding emulsifiers, specifically polyglycerine fatty acid esters (PGFEs), on the crystallization of palm stearin (PS), using synchrotron radiation X-ray diffraction and DSC methods. Our main aim was to examine the effects of the molecular shapes of PGFEs containing palmitic and oleic acid moieties at different ratios, the concentration of PGFE additives, and the cooling rate on the crystallization kinetics of PS in combined ways. We found that all PGFE additives retarded the crystallization of PS when the concentration of PGFEs was low and the cooling rate was low. However, crystallization was promoted when the concentration of PGFEs containing a high amount of palmitic acid moiety was increased and the cooling rate was increased. It was evident that the additive effects due to the PGFEs became less remarkable with increasing concentrations of oleic acid moiety. By contrast, emulsifiers containing palmitic acid moiety strongly affected the crystallization. We discuss the fact that crystallization was promoted by the template effects of PGFEs but was retarded by the disturbance of nucleation and subsequent crystal growth processes caused by the PGFE molecules.