Phase Behavior and Polymorphism of Saturated and Unsaturated Phytosterol Esters

Area of Science:

• Lipid chemistry and physical chemistry
• Materials science of esters
• Crystallization and phase behavior studies

Background:

• Phytosterol esters (PEs) are widely used in functional foods and pharmaceuticals.
• Understanding their physicochemical properties is crucial for formulation and application.
• The influence of fatty acid chain length and unsaturation on PE behavior is not fully elucidated.

Purpose of the Study:

• To investigate the impact of fatty acid chain length and unsaturation on phytosterol ester physicochemical properties.
• To analyze the crystallization and melting behavior of synthesized phytosterol esters.
• To correlate structural characteristics with macroscopic properties like melting temperature and morphology.

Main Methods:

• Synthesis of saturated and unsaturated phytosterol esters via esterification of β-sitosterol with various fatty acids.
• Non-isothermal crystallization and melting behavior analysis.
• X-ray diffraction for crystal structure determination, and microscopic analysis for morphology.

Main Results:

• Bilayer crystal structures were observed in saturated PEs and β-sitosteryl oleate.
• Lamellar spacing decreased with shorter fatty acid chains and higher unsaturation.
• Melting temperature and enthalpy increased with chain length but decreased with unsaturation; smaller spherulites formed with unsaturation.

Conclusions:

• Fatty acid chain length and unsaturation significantly dictate the physicochemical properties of phytosterol esters.
• These factors influence crystal structure, phase transitions, and morphology.
• Findings provide insights for designing phytosterol esters with tailored properties for specific applications.