chapter  9
Crystallization and Polymorphism of Fats
Pages 22

I. Crystallization: General Principles....................................................................................... 245 A. Supercooling ................................................................................................................ 246 B. Nucleation .................................................................................................................... 247 C. Crystal Growth............................................................................................................. 247 D. Crystal Geometry ......................................................................................................... 248 E. Crystal Polymorphism and Habit................................................................................. 248

II. Fat Crystallization ................................................................................................................ 249 A. Lipid Classification ...................................................................................................... 249 B. Triacylglycerol Crystal Packing Structure ................................................................... 250

III. Polymorphism and Phase Behavior of Natural Fats............................................................ 253 A. Nomenclature ............................................................................................................... 253 B. Phase Behavior ............................................................................................................ 254 C. Milk Fat........................................................................................................................ 255 D. Palm Oil ....................................................................................................................... 257 E. Lauric Fats ................................................................................................................... 257 F. Liquid Oils ................................................................................................................... 257 G. Hydrogenated Fats ....................................................................................................... 258 H. Cocoa Butter ................................................................................................................ 258

1. Cocoa Butter Polymorph Nomenclature ............................................................... 258 2. Polymorphic Formation and Transformation in Pure Cocoa Butter ..................... 258 3. Natural Fat Mixtures and Polymorphism.............................................................. 260 4. Effects of Emulsifiers and Other Additives .......................................................... 260 5. Intrinsic Seeding and Cocoa Butter Crystallization .............................................. 261

References ..................................................................................................................................... 263

Crystallization can be considered a subset of overall solidification. Solids are crystalline, semicrystalline, or amorphous. The crystallization process from solution first requires supersaturation; supercooling is a prerequisite for crystallizing from a melt. These phenomena lead to nucleation and crystal growth. This chapter emphasizes fat crystallization from the melt.