Slides from a talk that I gave on April 26th

1. Adventures in Chocolate
Naveen N. Sinha
Applied Physics Ph.D. Candidate
Harvard University

3. Find the key components Vary the components Eat chocolate

4. Find the key components Vary the components Eat chocolate

5. What foods are similar to chocolate?
FIND PHYSICAL ANALOGIES

6. To find the key components, find similarities to
other foods, such as coffee.
Cocoa bean Coffee beans

7. FAILURE: A watery brown liquid with oil residue
floating on top. Not delicious.
Crushed beans in basket Brewed cacao beans

8. Longer times in the spice grinder make a paste,
known as cocoa liquor.
Cocoa beans in spice grinder Cocoa liquor

9. Can we find a closer culinary analogy?
Cocoa bean Almond

10. Nut butters seem similar to cocoa liquor;
proteins and starches are suspended in fats.
solid particles liquid fats
x 1000
Walnut-cashew butter Microscopic view

11. Fat molecules, called triglycerides, are a
thousand times smaller than the particles.
triglyceride molecules
x 1000
Walnut-cashew butter Microscopic view

12. These triglyceride molecules are three fatty acid
molecules attached to a glycerol.
triglyceride molecules
glycerol
double-bond

13. More saturated fatty acids have higher melting
points than unsaturated ones.
All unsaturated Mixed All saturated
higher melting point

14. The saturation of chocolate fatty acids leads to a
melting point just above room temperature.
72°F 98.6 °F
J. Engmann and M. R. Mackley, “SEMI-SOLID PROCESSING OF CHOCOLATE AND COCOA BUTTER”
Trans IChemE, Part C, Food and Bioproducts Processing, 2006, 84(C2): 95–101

15. Harvesting, fermentation, drying
ORIGIN OF CACAO BEANS

16. cacao pods
remove contents
cacao beans and pulp
ferment 2-8 days
dry
dry cacao beans
H McGee, On Food and Cooking

17. Stephen Hubbes, Kallari

18. Miles Masci, Perfect Fuel

19. Miles Masci, Perfect Fuel

20. Miles Masci, Perfect Fuel

21. Stephen Hubbes, Kallari

22. Stephen Hubbes, Kallari

23. Stephen Hubbes, Kallari

24. Stephen Hubbes, Kallari

25. cacao pods
remove contents
cacao beans and pulp
ferment 2-8 days
dry
dry cacao beans
H McGee, On Food and Cooking

26. Roasting, Grinding, Refining
CACAO BEAN PROCESSING

27. dry cocoa beans
roast
vanilla,
nibs
lecithin,
sugar,
grind, refine milk
chocolate liquor
press conch
cocoa butter
cocoa cake
pulverize cool, form
cocoa powder chocolate
H McGee, On Food and Cooking

28. roast winnow grind re-grind
Taza Chocolate

29. dry cocoa beans
roast
vanilla,
nibs
lecithin,
sugar,
grind, refine milk
chocolate liquor
press conch
cocoa butter
cocoa cake
pulverize cool, form
cocoa powder chocolate
H McGee, On Food and Cooking

30. Many chocolate bars indicate the percentage of
ingredients that come from the cacao beans.
12% sugar
88% liquor

31. For our model system, chocolate is a suspension
of sugar and cocoa particles in cocoa butter.
Two views of chocolate through an optical microscope, using polarized light.

32. For our model system, chocolate is a suspension
of sugar and cocoa particles in cocoa butter.
sugar
cocoa
particles
cocoa
butter

33. Find the key components Vary the components Eat chocolate

34. What can we change about this model system?
sugar
cocoa
particles
cocoa
butter

35. Add stuff to the chocolate
CHANGE THE VARIABLES: I

36. VARIATION #1: Add olive oil (unsaturated fat) to
create spreadable chocolate.

37. Olive oil has more unsaturated fats and lowers
the overall melting point.
olive oil
higher melting point

38. VARIATION #2: Add coconut oil (saturated fat) to
create a scoop-able chocolate paste.

39. Coconut butter has more saturated fats and
raises the overall melting point.
coconut butter
higher melting point

40. VARIATION #3: Add corn syrup, which has water
and sugar, to make a pliable chocolate.

41. The sugars and cocoa particles are hydrophilic,
so they bind to the water in the syrup.
water sugar,
fat
cocoa particles
hydrophilic hydrophobic

42. The sugars and cocoa particles are hydrophilic,
so they bind to the water in the syrup.
water sugar fat
hydrophilic hydrophobic

43. VARIATION #4: Dilute with water and whisk in air
to create a chocolate mousse.
Cocoa butter crystallizes
see “chocolate chantilly” by Herve This

44. The cocoa butter crystals hold the air bubbles in
place, similar to a chocolate mousse.
Liquid cocoa butter, Solid cocoa butter,
bubbles incorporated bubbles held in place

45. FAILURE: Attempt to make Heston Blumenthal’s
chocolate soil leads to sticky mess.
Boil chocolate in syrup. Forms caramels, not crystals.

46. Change the crystal structure
VARY THE COMPONENTS

47. Chocolate fat molecules can arrange in at least
three different ways.
K Smith, Chocolate Tempering. Confectionary Manufacturing Expo, Brussels, Belgium, June 2006.

48. Chocolate fat molecules can arrange in at least
three different ways.
K Smith, Chocolate Tempering. Confectionary Manufacturing Expo, Brussels, Belgium, June 2006.

49. Each of these arrangements has a different
melting point.
T ( C)
36
33 29-34
30
27
20-27
24 ’
21 17-22
18
15

50. Heating and cooling can maximize the number
of crystals in the form.
T ( C)
36
33 29-34
30
27
20-27
24 ’
21 17-22
18
15

51. Heating and cooling can maximize the number
of crystals in the form.
T ( C)
36
33
30
27
24
21
18
15

52. Tempered chocolate has a shiny appearance,
compared to non-tempered chocolate.
200 m 200 m
Tempered Not tempered

53. Un-tempered chocolate can lead to a light-
colored discoloration, known as bloom.

54. Tempering is essential for making sculptures
from chocolate.
Enric Rovira

55. The chocolate rapidly sets into rigid sheets,
which can be cut into different shapes.

56. Can we temper at just one temperature?
T ( C)
36
33
30
27
24
21
18
15

57. Can we temper at just one temperature?

58. What other factors are important for the
tempering process?
50°C  RT 50°C  4°C 50°C  4°C 50°C  34°C 50°C  34°C
no agitation 4°C  RT 4°C  RT 32°C  RT 32°C  RT
agitation no agitation agitation no agitation
Amy Vo

59. Find the key components Vary the components Eat chocolate

60. Particle size
PHYSICAL DIFFERENCES

61. Step 1: Look at the glossiness of each chocolate.
Taza Mexicano Taza 87% Endangered Species 88% Jivara Lactee

62. Step 2. Observe how the chocolate breaks.
Taza Mexicano Taza 87% Endangered Species 88% Jivara Lactee

63. Step 3: Feel the microstructure of the chocolate.
Taza Mexicano Taza 87% Endangered Species 88% Jivara Lactee
Thanks to Adam Graham and Harvard Center for Nanoscale Science

64. Taza Mexicano Dark

65. Taza 87%

66. Endangered Species 88%

67. Valhrona Jivara Lactee

68. The conching process reduces the sizes of both
the sugar crystals and cocoa particles.
Smooth Smooth
Gritty Gritty

69. Sugar sweetens the naturally bitter chocolate,
but can mask other flavors.
More sweet
More bitter

70. The ratio of cocoa butter to cocoa particles
affects the consistency of the chocolate.
Smoother
Drier

71. Test #1
DOVE SILKY SMOOTH DARK CHOCOLATE

72. Lecithin and milk fat are common additives to
achieve a smoother texture.
lecithin
milk
fat

73. TEST #2
VALHRONA MANJARI DISKS

74. These discs are popular for confections due to
the high cocoa butter content.
sugar
cocoa
particles
cocoa
butter

75. TEST #3
ENDANGERED SPECIES 88%

76. The high cocoa content results in a dense,
intense chocolate.
sugar
cocoa
particles
cocoa
butter

77. TEST #4
ROGUE CHOCOLATE

78. This minimalist style is made with just cacao
beans and sugar, and no added cocoa butter.
sugar
cocoa
particles
liquor
cocoa
butter

79. Find the key components Vary the components Eat chocolate