Chocolatefest - The Cooper Union

Report
A Taste of Chocolate
Andrew Baik, Charmian Wu and Ruben
Savizky
Department 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 Bean Preparation
Fermentation
Drying
Transport
Cocoa Liquor Manufacture
Clean
Roast
Remove Shell
Grind
Enrobing
Mix (sugar, fat,
milk?)
Grind
Cocoa powder
Press
Cocoa Butter
Agitate (and add
cocoa butter)
Molding
Panning
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
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
• Insert picture of HPLC
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
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-areantioxidants/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!

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