Lipid Polymorphism and Crystallization Behavior

Lipid polymorphism refers to the ability of triglyceride and other lipid molecules to arrange into distinct crystal forms, each characterised by unique molecular packing, thermal stability and functional properties. During cooling from the melt or following tempering, lipids can crystallise into α, β′ and β polymorphs, differing in acyl‐chain tilt, layer spacing and subcell symmetry. These polymorphic transitions underpin the texture, mouthfeel and shelf life of food products such as chocolate and dairy, influence the release kinetics and stability of lipid‐based pharmaceuticals, and determine the performance of cosmetic and surfactant systems. Crystallisation behaviour is governed by factors including fatty acid chain length, degree of saturation, molecular symmetry and thermal history, and may be modified by co‐crystallisation in binary or ternary lipid mixtures. Tools such as differential scanning calorimetry, X-ray diffraction and polarized light microscopy permit the elucidation of phase diagrams and the sequential transformation between metastable and stable forms. Recent advances in molecular simulation and force‐field development have begun to bridge the gap between nanoscale packing and macroscopic properties, while novel processing methods—such as solvent-free melt technologies—offer pathways to control polymorphic form and crystal morphology without organic solvents. An integrated understanding of lipid polymorphism and crystallisation underpins global efforts to tailor functional lipids for food, pharmaceutical and industrial applications, ensuring reproducible quality and optimised performance.

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Research from all publishers

New experimental work has demonstrated how the cooling profile of model triglyceride mixtures dictates crystal morphology and surface energy, with slow cooling favouring heterogeneous β₁′‐rich films that delaminate rapidly in surfactant solutions, whereas rapid quenching yields uniform β₂′‐rich films with enhanced resistance to removal. A complementary study has introduced a coarse‐grained force field optimised for triacylglycerides, reproducing both crystal lattice parameters and melt densities, thereby enabling predictive simulations of polymorphic transitions and enthalpic differences across saturated and unsaturated systems. Further investigations into lipid‐based formulations produced by melting techniques have revealed that the inclusion of liquid lipids such as oleic acid and medium‐chain triglycerides can act as polymorphic modifiers of tristearin, accelerating the α-to-β transformation and stabilising the desired β form prior to storage, with direct implications for controlled drug release and long‐term stability of solid lipid microparticles.

Lipid Polymorphism and Crystallization Behavior publication trend

The graph below shows the total number of articles in lipid polymorphism and crystallization behavior across all publications each year (not limited to Nature Index journals).

Technical terms

Lipid polymorphism: The phenomenon by which the same lipid composition can crystallise into multiple structurally distinct forms.

Polymorphic transition: The conversion between different crystal forms, often thermally driven.

Triacylglycerol (TAG): A lipid molecule comprising glycerol esterified with three fatty acids, principal component of fats and oils.

α, β′, β forms: Designations for common TAG polymorphs, ordered by increasing thermodynamic stability and lattice order.

Differential scanning calorimetry (DSC): A technique measuring heat flow associated with thermal transitions to characterise crystallisation and melting behaviour.

X-ray diffraction (XRD): A method for determining crystal structure and layer spacing by analysing diffracted X-rays.

Molecular force field: A set of potential energy functions and parameters used in simulations to predict molecular interactions and macroscopic properties.

References

1. How triacylglycerol thermal history impacts film removal by surfactant solution. Journal of Colloid and Interface Science (2024).
2. COGITO: A Coarse-Grained Force Field for the Simulation of Macroscopic Properties of Triacylglycerides. Journal of Chemical Theory and Computation (2023).
3. Solvent-Free Melting Techniques for the Preparation of Lipid-Based Solid Oral Formulations. Pharmaceutical Research (2015).
4. Systematic Investigation of Co-Crystallization Properties in Binary and Ternary Mixtures of Triacylglycerols Containing Palmitic and Oleic Acids in Relation with Palm Oil Dry Fractionation. Foods (2020).
5. Structural models of metastable phases occurring during the crystallization process of saturated/unsaturated triacylglycerols. Journal of Applied Crystallography (2007).
6. Liquid Lipids Act as Polymorphic Modifiers of Tristearin-Based Formulations Produced by Melting Technologies. Pharmaceutics (2021).