BY: KAT E K I N Z Y F E B R U A RY 9 T H 2 0 1 5

CHOCOLATE “UNWRAPPED”: THE PROCESS OF MAKING CHOCOLATE

MOTIVATION

PROCESS OF MAKING CHOCOLATE

http://sweetmatterphysicist.com/images/chocolate_making_process_scheme_big.png

A lot of work just to make a simple piece of chocolate, right?

I would argue that it is totally worth it.

Plus, we’ve been doing this for a long time (maybe not as complex of a process but we are engineers and we are naturally inclined to make it

more difficult on ourselves)

PROCESS OF MAKING CHOCOLATE

http://sweetmatterphysicist.com/images/chocolate_making_process_scheme_big.png

HISTORY OF USE OF CACAO

• Cocoa tree from tropical parts of the Americas• Grown by Aztecs of Mexico

and Mayas in Central America• Fruit = “cacavacentli”,

drink prepared from fruit = “chocolatl” • Husked, roasted, ground,

mixed with spices, formed into cakes, dried, dissolved in hot or cold water [1]

http://www.annarbor.com/entertainment/food-drink/adventures-in-making-drinking-chocolatl/

WHAT CAN BE MADE FROM CACAO?

• Cocoa nibs – cookies, beer, chocolate covered, etc.

• Chocolate liquor - made into chocolate

• Cocoa powder – cooking applications

• Cocoa butter – chapstick, lotion

http://sciencefare.org/wp-content/uploads/2012/08/chocolate-processing-phase-21.jpg

WHERE IS COCOA HARVESTED?

• Main sources:• Brazil• Ghana• Nigeria• Dominican Republic

[1]

[2]

DOES THE PH HAVE AN EFFECT ON TASTE?

• Quality of taste independent of pH

• Some variation within countries (fermentation technique, type of beans, climate, etc.)

• Flavor score – • Acidic• Bitter• Fruity• Burnt• Hammy• Musty• Nutty• Sweet

[2]

Increasing pH

PROCESS OF MAKING CHOCOLATE

http://sweetmatterphysicist.com/images/chocolate_making_process_scheme_big.png

FERMENTING OF COCOA

• Yeast cells degrade glucose to ethanol

• Lactobacilli produce lactic acid, heat rises

• Acetic acid bacteria thrive in higher temperature environment [3]

• Aerobic spore-forming bacteria (can lead to off-flavors via C3 – C5 free fatty acids from this stage)

• Filamentous Fungi – not an important part of fermentation, can produce acid that impart off-flavors [4]

[4]

PROCESS OF MAKING CHOCOLATE

http://sweetmatterphysicist.com/images/chocolate_making_process_scheme_big.png

ROASTING

• Many many chemical reactions taking place• “browning reactions” – carbonyl-amine reactions

(non-enzymatic browning) AKA Maillard reactions• Hard to characterize all the reactions with

examples, however simplest step will be further explored… [5]

http://sciencegeist.net/the-maillard-reaction/

FIRST STEP

• Primary amino acid and carbonyl group reducing sugar (D-glucose) or aldehyde condense• Isomerizes (changes

orientation in space) *** very important that the end product is rearranged for later reactions to occur*** [5]

[5]

INTERMEDIATE

• This stage allows generation and interaction of compounds to yield flavor components and notes• Start with isomerized

products from first step• Possible reactions shown

to reach melanoidins which is the end product• This step is where

“browning reaction” term comes from [5]

[5]

PROCESS OF MAKING CHOCOLATE

http://sweetmatterphysicist.com/images/chocolate_making_process_scheme_big.png

CONCHING:MODERN DAY MORTAR AND PESTLE

• Benefits:• Expulsion of moisture• Loss of tannic acid• Free acetic acid• Full development of

aroma• Smoothing of texture

• Some say shape of particles changes, others say no• Viscosities decrease

with time of conche [1]

PROCESS OF MAKING CHOCOLATE

http://sweetmatterphysicist.com/images/chocolate_making_process_scheme_big.png

TEMPERING (THIS IS VERY IMPORTANT)

• Cocoa butter turns into polymorphs (raised temperatures)• Polymorph – “many” “shapes” [5]

[6]

POLYMORPHS

[7] [5]

ON THE MOLECULAR SCALE…

Goal:

[8]

ON THE MOLECULAR SCALE…

1.[8]

ON THE MOLECULAR SCALE…

2.[8]

ON THE MOLECULAR SCALE…

2.[8]

ON THE MOLECULAR SCALE…

2.[8]

ON THE MOLECULAR SCALE…

2.[8]

ON THE MOLECULAR SCALE…

3.

[8]

ON THE MOLECULAR SCALE…

3.

[8]

ON THE MOLECULAR SCALE…

3.

[8]

ON THE MOLECULAR SCALE…

3.

[8]

WHAT HAPPENS IF YOU DON’T TEMPER THE CHOCOLATE?

http://www.sugarhero.com/wp-content/uploads/2013/03/temper-chocolate-7_thumb.jpg

MYTHBUSTING

Are cocoa beans healthy? Chemicals that are chemopreventive agents based on antibiotic activities [3]

Is a little dark chocolate a day healthy?

Reduces oxidation of the LDL (low-density lipoprotein) cholesterol (bad cholesterol) [9]

Does chocolate have antioxidants?

High content of polyphenols – excellent radical scaventers (antioxidants), moderately protective against cardiovascular diseases and cancer [10]

MYTHBUSTING

Do people crave chocolate? Psychologically motivated, emotional stress, premenstrual phase, feeling of chocolate on tongue [11]

Does chocolate provide a feeling of happiness when consumed?

Can create a feeling of emotional elation, possible danger for addiction for predisposed people [12]

Is chocolate an aphrodisiac? No aphrodisiacally active substance detectable in cocoa, likely deeply anchored in social belief [13]

MYTHBUSTING

Is chocolate dangerous for animals to eat?

Theobromine which is in chocolate has a stimulatory effect on the central nervous system, not high enough of a dose to affect humans but it is degraded much more slowly in some animal species (dogs) so high quantities can cause death [14]

MYTHBUSTING

Is white chocolate actually chocolate?

No. it does not contain any chocolate solids, it is just cocoa butter, milk, and sugar [15]

[15]

MYTHBUSTING

Does chocolate have a significant amount of caffeine? (similar to a cup of coffee or tea)

[15]

BIBLIOGRAPHY

[1] P. S. Dimick, J. M. Hoskin, Chemico-physical Aspects of Chocolate Processing – A Review, Can. Insl. Fuud Sel. Technol. J. Vol. 14. No. 4. [October 1991] pp. 269-292.[2] S. Jinap, P. S. Dimick, R. Hollender, Flavour evaluation of chocolate formulated from cocoa beans from different countries, Food Control, Vol. 6. No. 2. [1995] pp. 105-110.[3] R. F. Schwan, A. E. Wheals, Crit. Rev.Food Sci. Nutr. 2004, 44, 205. PMID: 15462126.[4] Rosane F. Schwan & Alan E. Wheals, The Microbiology of Cocoa Fermentation and its Role in Chocolate Quality, Critical Reviews in Food Science and Nutrition, Vol. 44 No. 4, [2004] pp. 205-221, DOI: 10.1080/10408690490464104.[5] G. Tannenbaum, ed. G. B. Kauffman, Chocolate A Marvelous Natural Product of Chemistry, J. Chem Ed, Vol. 81 No. 8 [August 2004].[6] http://industrialchocolatemanufacturing.blogspot.com/2012/08/cocoa-butter-crystallisation-during.html[7] K. W. Smith, K. van Malssen, Presentation, http://www1.food.leeds.ac.uk/mp/LipidConference/AbstractKevinSmith.html#CB%20polymorphism.[8] http://chocolatealchemy.com/illustrated-tempering/[9] http://www.chemistryviews.org/details/news/1006809/A_Reason_to_Eat_Chocolate.html[10] P. Fryer, K. Pinschower, MRS Bull. Vol. 25 [2000]. www.mrs.org/publications/bulletin.[11] W. Michener, P. Rozin, Physiol. Behav. Vol. 56, [1994] pp. 419. DOI: 10.1016/0031-9384(94)90283-6 [12] www.nakos.de (German); www.oa.org (English)[13] http://www.chemistryviews.org/details/ezine/854777/Chocolate__The_Noblest_Polymorphism_III.html[14] http://vetmedicine.about.com[15] S. Schenker, The nutritional and physiological properties of chocolate, British Nutritional Foundation, Nutrition Bulletin, Vol. 25, [2000] pp. 303-313. [16] M.H.A. Jahurul, I. S. M Zaidul, N. A. N. Norulaini, F. Sahena, S. Jinap, J. Azmir, K. M. Sharif, A. K. Mohd Omar, Cocoa butter fats and possibilities of substitution in food products concerning cocoa varieties, alternative sources, extraction methods, composition, and characteristics, Journal of Food Engineering Vol. 117 [2013] pp. 467–476.