Controlling lipid crystallization across multiple length scales by directed shear flow.

Area of Science:

• Lipid crystallization
• Rheology
• Materials Science

Background:

• Lipid crystallization is crucial in adipose tissue formation, forensics, and food science.
• Understanding lipid crystallization under shear is vital for controlling material properties.

Purpose of the Study:

• To investigate the impact of shear rate on lipid crystallization and subsequent network formation.
• To elucidate the relationship between crystallite structure, aggregation, and macroscopic properties.

Main Methods:

• Utilized a triacylglycerol lipid model system.
• Employed polarized light microscopy, scanning electron microscopy, atomic force microscopy, and laser diffraction spectroscopy.
• Studied crystallization under laminar shear flows across various length scales.

Main Results:

• Shear rate during crystallization (γ̇_cryst) dictates acyl-chain structure and particle morphology (oblate to prolate).
• Crystallite aggregation into clusters is concentration-dependent and limits floc formation.
• High γ̇_cryst promotes fast cluster formation, leading to weak networks; low γ̇_cryst results in slow growth of larger flocs and strong networks.

Conclusions:

• Shear rate is a critical parameter controlling lipid crystallite morphology and network architecture.
• Findings have implications for designing soft tissue fillers, understanding microbial lipid networks, and optimizing food processing.
• The study provides a framework for tailoring lipid-based materials through controlled crystallization.