Low crystallization-rate and formation of crystalline clusters makes palm stearin unpopular in fat-based products especially in their post-processing stage. Addition of emulsifiers is commonly used to overcome these drawbacks, since they are believed to induce or stabilize specific polymorphs of palm stearin. Glyceryl monostearate (GMS) was applied in palm stearin (1%, 2%, and 4% w/w) in this study, and the mechanisms on crystallization of palm stearin were investigated by means of differential scanning calorimetry (DSC), X-ray diffraction (XRD), and polarized light microscopic (PLM) method. Data showed that GMS prompted the isothermal crystallization (15-30 °C) in a dose-dependent manner. Crystallization turned to low super-cooling sporadic nucleation at 30 °C. Besides, GMS led to an earlier onset of crystallization during cooling. GMS-palm stearin blends crystallized to form α polymorphs at first and subsequently underwent polymorphic transition to become β' polymorphs. Addition of 4% w/w GMS in palm stearin significantly decreased the size of crystals, which is helpful to reduce the grainy mouth feel of fat products in practice.
Keywords: Crystallization; Glyceryl monostearate; Palm stearin; Polymorphism.