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Cocoa Butter

Cocoa Butter. crystallization, tempering, bloom. Plan. Lipid structure, crystallization & polymorphism Tempering theory & practice Bloom. Fatty Acids. Stearic acid 18 carbon carboxylic acid linear molecule. Oleic Acid 16 carbon carboxylic acid single double bond puts a “kink”. O. C.

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Cocoa Butter

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  1. Cocoa Butter crystallization, tempering, bloom

  2. Plan • Lipid structure, crystallization & polymorphism • Tempering theory & practice • Bloom

  3. Fatty Acids Stearic acid 18 carbon carboxylic acid linear molecule Oleic Acid 16 carbon carboxylic acid single double bond puts a “kink” O C HO

  4. Fatty Acids in Cocoa Butter …plus about 5 others

  5. Triglycerides take on a tuning fork configuration

  6. Homogeneous Nucleation T>Tmelt T=Tmelt T<<Tmelt supercooling Crystal lattice True melt Crystal embryos

  7. Heterogeneous Nucleation T>Tmelt T=Tmelt T<Tmelt less supercooling Crystal lattice True melt Nucleation

  8. heating cooling 100% solid • SFC is a function of temperature • SFC is a function of temperature history • SFC is a function of time • SFC is a function of composition Solid Fat Content 100% liquid hot cold Temperature

  9. Polymorphism Molecular packing can vary by angle of tilt...

  10. …and by chain packing

  11. Consequently there are several types of triglyceride crystal Higher MP More dense More desirable

  12. Key Facts • Desirable forms have a high melting point • The higher melting point, the more stable • More stable fats are more dense • More stable forms are slow to form • Like crystals will grow from like • Cocoa butter can convert from a less to more stable form

  13. As the oil cools the fat molecules slow down • Eventually try to “stop” in contact with another molecule (crystal lattice) • It takes time to get into optimal position (most dense) • Pre-existing nuclei can help form a template

  14. Rapid cooling leads to a less well ordered structure!

  15. Cocoa butter • Cocoa butter is largely triglycerides • There has several stable crystal polymorphs • Good chocolate can only be made from the stable crystals

  16. Tempering Tempering is a time-temperature process ensure the formation of chocolate in the right crystal habit In practice this means we want 1-2% solids at ~32oC which will act as seeds when the melt is cooled

  17. Why 32oC?

  18. Tempering • Why temper? • Demolding • Snap • Gloss • Resistance to bloom • Temperature and time control

  19. Tempering Sequence 50oC Melt Cool - no crystallization Form mix of crystals Melt out unstable polymorphs 1 2 3 4 temperature 32oC 30-32oC 1 27oC 2 4 3 time

  20. Tempering Practice • Hand tempering • Batch tempering • Continuous tempering • Temper meters

  21. Melt Cool - no crystallization Form mix of crystals Melt out unstable polymorphs 1 2 3 4 Hand Tempering • Melt fat • Pour melt onto slab and work with spatulas • Return semicrystalline batch back to warm melt • Mold chocolate

  22. Melt Cool - no crystallization Form mix of crystals Melt out unstable polymorphs 1 2 3 4 Kettle Tempering

  23. 3-stage Tempering Machine 1 2 3

  24. Tempering • Tempering is a process to ensure the formation of stable crystals • Tempering is a time-temperature process • Tempering can be done as a batch or continuous process • Degree of temper can be measured from a cooling curve

  25. What is bloom? • White “moldy” appearance at the surface • Major reason for product failure • NOT a health hazard Often caused by large fat crystals growing from the surface and scattering light

  26. Types of Bloom • High temperature bloom • Low temperature bloom • Fat migration bloom

  27. High Temperature Bloom • Fat is stored hot enough to melt (~35oC) • Fat resolidifies and is no longer tempered • Untempered chocolate rapidly grows bloom U se a high melting fat if you can’t be certain of distribution temperature

  28. Low Temperature Bloom • In well tempered chocolate stored below its melting point • Associated with V to VI transition • Occurs faster at high temperatures (esp. if temp. cycles) Reduce storage temperature

  29. Migration Bloom • The movement of fat from an enrobed center to the surface • Dissolves some cocoa butter and carries it to the surface • Cocoa butter recrystalizes at the surface

  30. How to avoid bloom • Temper the chocolate properly • Store cool • Add butter-fat • Add emulsifier (e.g. sorbitan monostearate)

  31. Bloom • A moldy white deposit on the surface • Large fat crystals formed by migration and recrystallization • Not a health hazard but it is a cause for product rejection • Avoid by good tempering and controlled storage

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