A Taste of ChocolateAndrew Baik, Charmian Wu and Ruben SavizkyDepartment of Chemistry, The Cooper Union

41 Cooper Square, New York, NY 10003

A Brief History of Chocolate• Maya – chocolate plantations around 600 A.D.

– Aztecs and Incas also used cocoa • Columbus brings chocolate to Europe around

1500– Reserved for the aristocracy– Sugar was added, but it still did not appeal to

most• Milk was added in 1727 by the British• Van Houten develops a cocoa process in 1828

which removes some of the fat from cocoa butter– Cocoa beans were pressed, milled and treated

with alkali to generate a powder that could be dispersed in hot water or milk

A Brief History of Chocolate• Fry designs a factory for producing

eating chocolate in 1867 in the UK– Produced by using cocoa butter,

sugar and cocoa nibs (cotyledons)– Run on steam power

• Peter creates milk chocolate in 1875 in Switzerland

• Lindt creates a smoother tasting chocolate in 1880 by making smaller particles using a conche

• 1930 – white chocolate is made from sugar, milk powder and cocoa butter

Chocolate manufacturing process

Cocoa Liquor Manufacture

Clean Roast Remove Shell Grind

Cocoa Bean Preparation

Fermentation Drying Transport

Mix (sugar, fat, milk?) Grind Agitate (and add

cocoa butter)

Enrobing

Molding

Panning

Press

Cocoa powder

Cocoa Butter

In pictures (and German)

• Harvest Bean cracking Fermentation Drying Roasting Milling Cocoa mass Pressing or mixing Molding

Where does chocolate come from?

Chemical composition of chocolate

• Cocoa mass • Cocoa aroma

Component Percentage (%)

Cocoa butter 54

Egg white 11.5

Organic acids 9.5

Cellulose 9

Polyphenols 6

Water 6

Minerals and salts 2.6

Theobromine 1.2

Sugar 1

Caffeine 0.2

OH

O

O

O

N

N

O

O

S S

O

H

Chemical composition of chocolate

• 3 main types of fat– 40%% POS, 25%

SOS and 20% POP• Cane sugar is a

disaccharide of glucose and fructose

• Lecithin is commonly from soy beans (phosphatidylcholine)

Typical nutrition facts for chocolate (per 100g bar)

Plain Milk White

Energy (kcal) 530 518 553

Protein (g) 5 7 9

Carbohydrate (g) 55 57 58

Fat (g) 32 33 33

Calcium (mg) 32 224 272

Magnesium (mg) 90 59 27

Iron (mg) 3 2 0.2

Chemical analysis of chocolate

• High-Pressure Liquid Chromatography (HPLC)– Separate and identify individual components of

chocolate (methylxanthines)• Attenuated Total Reflectance Fourier

Transform Infrared Spectroscopy (ATR FT-IR)– Spectroscopically distinguish various types of

chocolate

HPLC procedure

• Dissolve chocolate in methanol/water

• Pass through C18 SPE column

• Inject into HPLC and analyze with a UV detector (l = 273 nm)

• Establish concentrations using a calibration curve

• Insert picture of HPLC

HPLC Results

• Insert HPLC spectrum for single caffeine standard

HPLC Results

• Insert HPLC spectrum for single theobromine standard

HPLC Results

• Explain chocolate sample (#, which peak is which, etc)

ATR FT-IR procedure

• Crush sample and analyze

• Establish pattern recognition using Continuous Wavelet Transform (CWT) and Principal Component Analysis (PCA)

• ATR FT-IR spectrum of sample 19

ATR FT-IR results

• Explain regions

CWT results

• Explain what was done

PCA Analysis

• Explain what was done• Show graph of results

Methylxanthine content of various chocolates and beverages

Serving Caffeine (mg) Theobromine (mg)

Milk chocolate 50 g 10.0 70

Plain chocolate 50 g 22.0 209

White chocolate 50 g Trace 1.1

Strong ground coffee

Cup 85.0 ---

Instant coffee Cup 60.0 ---

Tea Cup 50.0 2.0

Cola Can 40.0 ---

Health benefits to consuming chocolate

• ORAC (Oxygen Radical Absorbance Capacity) of chocolate is the highest among known foods

Conclusions

• Comparisons of x vs y (caffeine vs dollars? Specific IR Peak vs dollars?)

• Are there any trends in the cacao content• Did PCA tell us anything?

References

• Beckett, S. T., The Science of Chocolate, 2nd ed., RSC Publishing, UK, 2009

• http://www.barry-callebaut.com/1897• http://www2.dpi.qld.gov.au/horticulture/6223.html• http://www.veryveryvegan.com/what-are-antioxidants

/what-are-antioxidants-by-david-wolfe-jd• Include papers you have used (J Chem Ed for HPLC,

others for IR, etc) – make sure citation is complete (see below): Lastname, X., Journal Name, Year, Issue, Page

• Roth, K., Chem. Unserer Zeit, 2005, 39, 416-428

Acknowledgments

• The Cooper Union– Yash Risbud– Sarah Lerner– Victoria Heinz– Patrick Chiu– Volunteers at

Chocolatefest

• Science House– James Jorasch– Megan Kingery– Gabi de Wit

• Dr. Stefan Koenig for knowledge of German, chemistry and chocolate!