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On behalf of u Cocoa Butter Crystallisation Kevin W. Smith & Kees van Malssen Unilever R&D Colworth.

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Presentation on theme: "On behalf of u Cocoa Butter Crystallisation Kevin W. Smith & Kees van Malssen Unilever R&D Colworth."— Presentation transcript:

1 on behalf of u Cocoa Butter Crystallisation Kevin W. Smith & Kees van Malssen Unilever R&D Colworth

2 October Outline  Introduction  Cocoa Butter and Chocolate  Cocoa Butter Crystallisation  Phase Transformations  Phase Behaviour and Crystallites  Conclusion

3 October Cocoa Butter & Chocolate  Crucial role in chocolate characteristics  Gloss  Snap  Texture  Cool melting in mouth  Shelf-life  Important to crystallise cocoa butter correctly 10  m

4 October Fat Polymorphism  Crystal Structure  few triacylglycerols known  main components of cocoa butter not known POP, POSt and StOSt many proposed structures  natural fats are complex mixtures observed crystal structure is an average new polymorphs may occur

5 October Cocoa Butter Polymorphism  Wille and Lutton (JAOCS, 1966)

6 October Cocoa Butter Polymorphism  Current understanding

7 October Static Isothermal Crystallisation     /sub-  liquid T c (°C) 10s20s30s2m3m4m10m20m30m2h3h6h12h18h2d3d4d2w3w 1 min1 hour1 day1 week Time (logarithmic)

8 October  ' Phase Range Diffraction  ' 25.0  ' 22.5  ' 20.0  ' 17.5  ' 15.0  ' 12.5  ' 10.0  ' d (Å)

9 October  ' Melting Dependent on Crystallisation Temperature

10 October Cocoa Butter Phase Scheme Melt  VI VV  or  sub-  '' Solvent

11 October Assignment of Polymorphs

12 October Phase Behaviour and Crystallites B (%) AB Temperature 100 Liquid L+S Solid

13 October Crystallites Composition

14 October Crystallites - Small Crystals

15 October Crystallites - Different Sizes

16 October Crystallites - Different Composition

17 October Complex Phase Behaviour B (%) AB Temperature L L+S B L+S A SBSB SASA S A + S B

18 October Cocoa Butter Crystallisation  Composition dependent  Solidification in two stages  high melting fraction first molten cocoa butter cooled to 30°C will develop a cloudiness but will not crystallise over 12 weeks  bulk second  Increasing first stage may not accelerate second stage trisaturated triacylglycerols are not good accelerators

19 October Memory Effect & Crystallisation  Memory of  crystal form remains in liquid cocoa butter  up to 7°C above melting point  Subsequent crystallisation occurs into stable  form  a type of seeding  can be used to 'temper' chocolate  Temperature for loss of memory effect is independent of cocoa butter composition

20 October Summary  Assignment of polymorphs to melting points has been mistaken  Solidification temperature determines phase, more than cooling rate  Phases develop faster through phase transitions than through nucleation   phases do not crystallise from the melt (excluding seeding effects)

21 October Acknowledgements  Unilever R&D Colworth: Dr. Kees van Malssen  Loders Croklaan  University of Amsterdam: A van Langevelde, R Peschar, H Schenk  Netherlands Foundation for Chemical Research (NWO/CW) and Dutch Technology foundation (STW)

22 October

23 October Additional  Wille and Lutton  I sub  mp 17  II  mp 23  III  ' mp 25  IV  ' mp 28  V  mp 33  VI  mp 36  Van Malssen   / sub  mp 0   mp 17   ' xmp 23*   ' ymp 25*   ' zmp 28*   mp 31   mp 33 * and many more possible!


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