Adventures in Chocolate

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

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Slides from a talk that I gave on April 26th

Transcript of Adventures in Chocolate

Page 1: Adventures in Chocolate

Adventures in Chocolate

Naveen N. SinhaApplied Physics Ph.D. CandidateHarvard University

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Find the key components Vary the components Eat chocolate

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Find the key components Vary the components Eat chocolate

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FIND PHYSICAL ANALOGIESWhat foods are similar to chocolate?

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To find the key components, find similarities to other foods, such as coffee.

Cocoa bean Coffee beans

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FAILURE: A watery brown liquid with oil residue floating on top. Not delicious.

Crushed beans in basket Brewed cacao beans

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

Cocoa beans in spice grinder Cocoa liquor

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Can we find a closer culinary analogy?

Cocoa bean Almond

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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

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Fat molecules, called triglycerides, are a thousand times smaller than the particles.

Walnut-cashew butter Microscopic view

triglyceride molecules

x 1000

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These triglyceride molecules are three fatty acid molecules attached to a glycerol.

triglyceride molecules

double-bond

glycerol

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More saturated fatty acids have higher melting points than unsaturated ones.

higher melting point

All unsaturated All saturatedMixed

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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

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ORIGIN OF CACAO BEANSHarvesting, fermentation, drying

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remove contents

ferment 2-8 days

cacao pods

cacao beans and pulp

dry

dry cacao beans

H McGee, On Food and Cooking

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Stephen Hubbes, Kallari

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Miles Masci, Perfect Fuel

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Miles Masci, Perfect Fuel

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Miles Masci, Perfect Fuel

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Stephen Hubbes, Kallari

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Stephen Hubbes, Kallari

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Stephen Hubbes, Kallari

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Stephen Hubbes, Kallari

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remove contents

ferment 2-8 days

cacao pods

cacao beans and pulp

dry

dry cacao beans

H McGee, On Food and Cooking

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CACAO BEAN PROCESSINGRoasting, Grinding, Refining

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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

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grind re-grindwinnowroast

Taza Chocolate

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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

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Many chocolate bars indicate the percentage of ingredients that come from the cacao beans.

12% sugar

88% liquor

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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.

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

sugar

cocoa particles

cocoa butter

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Find the key components Vary the components Eat chocolate

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What can we change about this model system?

sugar

cocoa particles

cocoa butter

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CHANGE THE VARIABLES: IAdd stuff to the chocolate

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

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

higher melting point

olive oil

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

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

higher melting point

coconut butter

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

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

water sugar, cocoa particles fat

hydrophilic hydrophobic

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

water sugar fat

hydrophilic hydrophobic

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VARIATION #4: Dilute with water and whisk in air to create a chocolate mousse.

Cocoa butter crystallizes

see “chocolate chantilly” by Herve This

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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

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FAILURE: Attempt to make Heston Blumenthal’s chocolate soil leads to sticky mess.

Boil chocolate in syrup. Forms caramels, not crystals.

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VARY THE COMPONENTSChange the crystal structure

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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.

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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.

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17-22

20-27

29-34

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T (°C)

a

b’

b

Each of these arrangements has a different melting point.

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17-22

20-27

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a

b’

b

Heating and cooling can maximize the number of crystals in the b form.

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Heating and cooling can maximize the number of crystals in the b form.

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Tempered chocolate has a shiny appearance, compared to non-tempered chocolate.

Tempered Not tempered

200 mm200 mm

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

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Tempering is essential for making sculptures from chocolate.

Enric Rovira

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

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Can we temper at just one temperature?

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Can we temper at just one temperature?

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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

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Find the key components Vary the components Eat chocolate

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PHYSICAL DIFFERENCESParticle size

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Taza Mexicano Taza 87% Endangered Species 88% Jivara Lactee

Step 1: Look at the glossiness of each chocolate.

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Taza Mexicano Taza 87% Endangered Species 88% Jivara Lactee

Step 2. Observe how the chocolate breaks.

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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

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Taza Mexicano Dark

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Taza 87%

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Endangered Species 88%

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Valhrona Jivara Lactee

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

Smooth

Gritty

Smooth

Gritty

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

More sweet

More bitter

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

Smoother

Drier

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DOVE SILKY SMOOTH DARK CHOCOLATETest #1

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

milk fat

lecithin

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VALHRONA MANJARI DISKSTEST #2

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

sugar

cocoa particles

cocoa butter

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ENDANGERED SPECIES 88%TEST #3

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The high cocoa content results in a dense, intense chocolate.

sugar

cocoa particles

cocoa butter

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ROGUE CHOCOLATETEST #4

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

sugar

cocoa particles

cocoa butter

liquor

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Find the key components Vary the components Eat chocolate

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