Crystallization Behaviour of Glyceryl Monooleate and Its Effect on the Crystallization and Texture Characteristics of Palm Stearin

The crystallization behaviour and texture characteristics of specialty fats and oils are influenced by glyceryl monostearate (GMS), a commonly used food emulsifier. Crude glycerol monooleate (GMO) was synthesised through enzymatic synthesis and subsequently purified to high-purity GMO using the solvent crystallisation method. The microscopic crystal structure and isomer ratio of GMO were analysed by using techniques such as polarized light microscopy (PLM) and nuclear magnetic resonance hydrogen spectroscopy (1H-NMR). Moreover, 2wt% GMO was added to palm stearin (PST) under melting and stirring in order to investigate the effect of GMO crystallization behaviour on the crystallization and texture properties of PST. Results showed that, the content of crude GMO (56.7%) was significantly increased to 90.0% after purification (P<0.05), with the ratio of sn-1 (3) GMO (91.4%) to sn-2 GMO (9.6%) approximately 9:1. Besides, comparing with hardness (700 g) and the crystal size (~50 μm) of PST, the addition of 2wt% GMO/GMS was found to significantly reduce its hardness(~460 g) and crystal size (~10 μm) (P<0.05). After 10 d of storage, a finer and denser crystalline network was observed in 2% GMO+PST. Moreover, the hardness of 2% GMO+PST was significantly reduced compared to that of PST (P<0.05), which could be attributed to the regulatory effect of GMO on the crystallization behaviour of PST. In conclusion, this paper provides fundamental data on the thermodynamic properties and microscopic crystal structure of high-purity GMO, and elucidates the mechanism by which GMO influences the crystallization behaviour and texture characteristics of PST. These findings offer valuable insights into the potential use of GMO as an emulsifier in specialty fats and oils.