Over the centuries, people have invented new ways todeliver the flavor and texture of chocolate.
For most of its history, cocoa beans were used for thick,strongly-flavored beverages.
Like milk or cream, hot chocolate is an oil-in-wateremulsion, which makes it a viscous liquid. The cocoa solids likely help stabilize the emulsions and prevent separation.
The Mesoamerican drinks were bittersweet, flavorful,and thicker than much of todays’ hot chocolate. Atole: blue corn atole, unsweetened 99% chocolate, honey, chili, salt. Pepper allspice: unsweetened 99% chocolate, New Mexican raw wildflower honey, hibiscus flowers, spices, Catarine chili, and Mexican vanilla. Rose Almond: unsweetened 99% chocolate, agave nectar, almond, roses, Chipotle Morita chili, and Mexican vanilla. Kakawa Chocolate House, Santa Fe, NM
The European beverages were sweeter andincorporated new ingredients, including milk. 1631 Spanish: 73.5% chocolate, evaporated cane juice, almonds, hazelnuts, roses, spices, Ceylon cinnamon, Red Chimayo chili, and Mexican vanilla. 1680 English: milk, 61% chocolate, egg yolks, sherry, orange blossoms, cinnamon. 1790 Jeffersonian: 73.5% chocolate, cane sugar, nutmeg, Mexican vanilla. Kakawa Chocolate House, Santa Fe, NM
By reincorporating additional cocoa butter,chocolate can be molded into its familiar bar form.
In bar chocolate, the aqueous continuous phase of thehot cocoa is replaced with solid cocoa butter. The cocoa solids are stabilized by a network of cocoa butter crystals. Taza Chocolate
The create this solid dispersion, cocoa beans areground and combined with additional cocoa butter. Roast Winnow Grind Re-grinddevelop flavor remove husks extract cocoa add sugar, butter cocoa butter Taza Chocolate
Trader Joe’s 72% Taza 70% bar 100 mm 100 mm Callebaut 100% Cocoa butter 100 mm 100 mm 23
The melting transition of the cocoa butter in chocolateis responsible for its distinctive texture. Cocoa butter (fats) Cocoa solids (protein, carbs) Chocolate dissolved in acetone
I’ve used oscillating shear wave rheology toquantitatively study changes in the texture. Purely elastic T = 1/w Stress Strain time w Purely viscous Stress time Strain
The rheometer can help quantify the liquid to solidphase transition in cocoa butter. elastic modulus viscous modulus -- axial force
Cocoa butter has a narrow melting range betweenthose of olive oil and coconut butter. Olive oil Coconut butter
Like other edible fats, the fats in cocoa butter aretriglycerides made from fatty acids and glycerol. HO O stearic acid HO OH O OH glycerol oleic acid OH HO O palmitic acid
Like other edible fats, the fats in cocoa butter aretriglycerides made from fatty acids and glycerol.
The differences in the melting point are due to thecomposition of triglycerides. 100% Poly-unsat. 80% Weight % 60% Mono-unsat. 40% Saturated 20% 0% Peanut oil Cocoa Coconut Olive oil butter butter
The fraction of solid cocoa butter decreases as the temperature increases, so it quickly melts in the mouth.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
The chocolate can also be tempered, for a glossyappearance that is resistant to bloom. 200 mm 200 mm Tempered Not tempered
Tempered chocolate also breaks cleanly and with anaudible snap, from the release of elastic energy. 200 mm 200 mm Tempered Not tempered
Cocoa butter, like many edible fats, occurs in severaldifferent crystalline phases. a b b more stable, higher melting pointK Sato and S Ueno, "Polymorphism in Fats and Oils", Bailey’s Industrial Oil and FatProducts, Sixth Edition. 2005.
Each phase has a different melting point. The b form has the highest melting point is most desirable.T ( C) 36 33 b 30 27 24 b’ 21 18 a 15
The chocolate is super-cooled, then re-heated, to maximize the number of b crystals.T ( C) 36 33 b 30 27 24 b’ 21 18 a 15 Time
The goal of tempering is as many and as small crystals as possible throughout the cocoa butter. 50 mm 50 mm Tempered Un-temperedMarty and Marangoni, “Effects of Cocoa Butter Origin, Tempering Procedure, andStructure on Oil Migration Kinetics” Crystal Growth & Design, Vol. 9, No. 3710, 2009
More recently, chocolatiers are experimenting withnovel ways of presenting chocolate.
Water and chocolate can be whipped into astable foam, known as chocolate chantilly. 2 parts chocolate 1 part water 1 part chocolate 1 part water
The chocolate dessert at Alinea features frozenchocolate foam and square chocolate sauce drops.
I’ve had some success replicating this effect in lab…