Adventures in Chocolate
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Transcript of Adventures in Chocolate
Adventures in Chocolate
Naveen N. SinhaApplied Physics Ph.D. CandidateHarvard University
Find the key components Vary the components Eat chocolate
Find the key components Vary the components Eat chocolate
FIND PHYSICAL ANALOGIESWhat foods are similar to chocolate?
To find the key components, find similarities to other foods, such as coffee.
Cocoa bean Coffee beans
FAILURE: A watery brown liquid with oil residue floating on top. Not delicious.
Crushed beans in basket Brewed cacao beans
Longer times in the spice grinder make a paste, known as cocoa liquor.
Cocoa beans in spice grinder Cocoa liquor
Can we find a closer culinary analogy?
Cocoa bean Almond
Nut butters seem similar to cocoa liquor; proteins and starches are suspended in fats.
Walnut-cashew butter Microscopic view
solid particles liquid fats
x 1000
Fat molecules, called triglycerides, are a thousand times smaller than the particles.
Walnut-cashew butter Microscopic view
triglyceride molecules
x 1000
These triglyceride molecules are three fatty acid molecules attached to a glycerol.
triglyceride molecules
double-bond
glycerol
More saturated fatty acids have higher melting points than unsaturated ones.
higher melting point
All unsaturated All saturatedMixed
The saturation of chocolate fatty acids leads to a melting point just above room temperature.
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
98.6 °F72°F
ORIGIN OF CACAO BEANSHarvesting, fermentation, drying
remove contents
ferment 2-8 days
cacao pods
cacao beans and pulp
dry
dry cacao beans
H McGee, On Food and Cooking
Stephen Hubbes, Kallari
Miles Masci, Perfect Fuel
Miles Masci, Perfect Fuel
Miles Masci, Perfect Fuel
Stephen Hubbes, Kallari
Stephen Hubbes, Kallari
Stephen Hubbes, Kallari
Stephen Hubbes, Kallari
remove contents
ferment 2-8 days
cacao pods
cacao beans and pulp
dry
dry cacao beans
H McGee, On Food and Cooking
CACAO BEAN PROCESSINGRoasting, Grinding, Refining
roast
grind, refine
press conch
pulverize cool, form
cocoa powder chocolate
chocolate liquor
dry cocoa beans
cocoa cake
vanilla, lecithin, sugar, milk
cocoa butter
nibs
H McGee, On Food and Cooking
grind re-grindwinnowroast
Taza Chocolate
roast
grind, refine
press conch
pulverize cool, form
cocoa powder chocolate
chocolate liquor
dry cocoa beans
cocoa cake
vanilla, lecithin, sugar, milk
cocoa butter
nibs
H McGee, On Food and Cooking
Many chocolate bars indicate the percentage of ingredients that come from the cacao beans.
12% sugar
88% liquor
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.
For our model system, chocolate is a suspension of sugar and cocoa particles in cocoa butter.
sugar
cocoa particles
cocoa butter
Find the key components Vary the components Eat chocolate
What can we change about this model system?
sugar
cocoa particles
cocoa butter
CHANGE THE VARIABLES: IAdd stuff to the chocolate
VARIATION #1: Add olive oil (unsaturated fat) to create spreadable chocolate.
Olive oil has more unsaturated fats and lowers the overall melting point.
higher melting point
olive oil
VARIATION #2: Add coconut oil (saturated fat) to create a scoop-able chocolate paste.
Coconut butter has more saturated fats and raises the overall melting point.
higher melting point
coconut butter
VARIATION #3: Add corn syrup, which has water and sugar, to make a pliable chocolate.
The sugars and cocoa particles are hydrophilic, so they bind to the water in the syrup.
water sugar, cocoa particles fat
hydrophilic hydrophobic
The sugars and cocoa particles are hydrophilic, so they bind to the water in the syrup.
water sugar fat
hydrophilic hydrophobic
VARIATION #4: Dilute with water and whisk in air to create a chocolate mousse.
Cocoa butter crystallizes
see “chocolate chantilly” by Herve This
The cocoa butter crystals hold the air bubbles in place, similar to a chocolate mousse.
Liquid cocoa butter,bubbles incorporated
Solid cocoa butter,bubbles held in place
FAILURE: Attempt to make Heston Blumenthal’s chocolate soil leads to sticky mess.
Boil chocolate in syrup. Forms caramels, not crystals.
VARY THE COMPONENTSChange the crystal structure
a ’b b
K Smith, Chocolate Tempering. Confectionary Manufacturing Expo, Brussels, Belgium, June 2006.
Chocolate fat molecules can arrange in at least three different ways.
a ’b b
K Smith, Chocolate Tempering. Confectionary Manufacturing Expo, Brussels, Belgium, June 2006.
Chocolate fat molecules can arrange in at least three different ways.
17-22
20-27
29-34
36
33
30
27
24
21
18
15
T (°C)
a
b’
b
Each of these arrangements has a different melting point.
17-22
20-27
29-34
36
33
30
27
24
21
18
15
T (°C)
a
b’
b
Heating and cooling can maximize the number of crystals in the b form.
36
33
30
27
24
21
18
15
T (°C)
Heating and cooling can maximize the number of crystals in the b form.
Tempered chocolate has a shiny appearance, compared to non-tempered chocolate.
Tempered Not tempered
200 mm200 mm
Un-tempered chocolate can lead to a light-colored discoloration, known as bloom.
Tempering is essential for making sculptures from chocolate.
Enric Rovira
The chocolate rapidly sets into rigid sheets, which can be cut into different shapes.
36
33
30
27
24
21
18
15
T (°C)
Can we temper at just one temperature?
Can we temper at just one temperature?
What other factors are important for the tempering process?
50°C RTno agitation
50°C 4°C4°C RTagitation
50°C 4°C4°C RTno agitation
50°C 34°C32°C RTagitation
50°C 34°C32°C RTno agitation
Amy Vo
Find the key components Vary the components Eat chocolate
PHYSICAL DIFFERENCESParticle size
Taza Mexicano Taza 87% Endangered Species 88% Jivara Lactee
Step 1: Look at the glossiness of each chocolate.
Taza Mexicano Taza 87% Endangered Species 88% Jivara Lactee
Step 2. Observe how the chocolate breaks.
Taza Mexicano Taza 87% Endangered Species 88% Jivara Lactee
Step 3: Feel the microstructure of the chocolate.
Thanks to Adam Graham and Harvard Center for Nanoscale Science
Taza Mexicano Dark
Taza 87%
Endangered Species 88%
Valhrona Jivara Lactee
The conching process reduces the sizes of both the sugar crystals and cocoa particles.
Smooth
Gritty
Smooth
Gritty
Sugar sweetens the naturally bitter chocolate, but can mask other flavors.
More sweet
More bitter
The ratio of cocoa butter to cocoa particles affects the consistency of the chocolate.
Smoother
Drier
DOVE SILKY SMOOTH DARK CHOCOLATETest #1
Lecithin and milk fat are common additives to achieve a smoother texture.
milk fat
lecithin
VALHRONA MANJARI DISKSTEST #2
These discs are popular for confections due to the high cocoa butter content.
sugar
cocoa particles
cocoa butter
ENDANGERED SPECIES 88%TEST #3
The high cocoa content results in a dense, intense chocolate.
sugar
cocoa particles
cocoa butter
ROGUE CHOCOLATETEST #4
This minimalist style is made with just cacao beans and sugar, and no added cocoa butter.
sugar
cocoa particles
cocoa butter
liquor
Find the key components Vary the components Eat chocolate