Influence of shear on fat crystallization

• Shear greatly accelerates fat nucleation and polymorphic transformations.
• Below critical shear rates, aggregation is promoted while above it is hindered.
• Shear affects fat crystallization at the nanoscale.
• Shear may cause orientation of fat crystals.
• Shear may be used to form new spheroidal crystal microstructures.

Processing conditions greatly impact fat crystallization kinetics and growth mechanisms. Recently, there has been increased interest in elucidating the role of shear on fat crystallization. This review provides an overview of fat crystallization under static conditions followed by a summary of the current body of work pertaining to the effects of shear on fat crystallization, namely its effects on nucleation and growth, crystal network formation, polymorphic transitions, and microstructure modification at different length scales. The effects of shear are usually tied to critical shear rates but shear generally enhances nucleation and growth, accelerates crystallization and polymorphic transitions, and can cause orientation and structuring of fat crystal networks.