Science

What is chocolate?

Chocolate is a solid mixture. In its basic form, it is composed of cacao powder, cocoa butter, and some type of sweetener such as sugar; however, modern chocolate includes milk solids, any added flavors, modifiers, and preservatives.

Cacao is the plant matter which lends the unique tast and bitterness to chocolate. The chocolate mixture is made of aggregations of micro particles of cacao & sugar and globules of cocoa butter fat milk solids.

The word "chocolate" comes from the Nahuatl word xocolatl for "bitter water", referring to its original incarnation as a hot, spiced beverage in the Mayan and Aztec traditions.

What's in typical chocolate?

• 10-20% cocoa solids
• 8-16% milk solids
• 32-60% sugar
• 10-20% cocoa butter
• 1.2% theobromine & polyphenols

How is chocolate made?

1. Harvest: Cut and crack open pods for beans
2. Ferment: Let micro-organisms and heat kill bean and develop flavor
3. Dry and Ship: Sun dry beans to preserve them for travel to chocolate-making factories
4. Clean: Remove dirt, sand, and debris
5. Winnow: Remove bean shell from cotyledon (nib), saving the flavorful nib
6. Roast: Heat the nib to develop its flavor
7. Grind and Mill: Release cocoa butter fat and generate coarse particles of cacao from the nib
8. Mix: Combine cacao, cocoa butter, milk, sugar, and flavors
9. Conch: Slowly mix ingredients under heat while continuously grinding to make a smooth texture
10. Temper: Crystallize the cocoa butter to form a solid that is easy to snap and melts in the mouth
11. Form: Pour and cast chocolates

Where does chocolate come from?

Cacao comes from the cacao tree, Theobroma cacao, a member of the evergreen family Sterculiaceae. The word "theobroma" literally means "food of the gods," indicating chocolate's exalted status in both ancient and modern tastes!

Cacao trees grow in tropical climates with a high degree of moisture. There are three major varieties: Criollo, Forestero, and Trinitario. Criollo trees yield mild, complex chocolate but are less hardy and more rare. Forestero makes up the majority of modern chocolate product, and Trinitario is a hybrid originally from Trinidad that is used as a supplement to Forestero.

Cacao is made from the cotyledons ("seed leaves", the nibs) of the beans. The beans are found in cacao pods (called cherelles). Every cacao bean is genetically unique!

Cacao pods are usually 200 to 250 g and contain 30-45 beans, They are usually harvested by hand to avoid damage to the beans.

Cocao butter chemistry

Fats and oils are organic molecules made up of three fatty acids chemically linked by an ester bond to glycerol. Fats are solid at room termperature, while oils are liquid.

Cocoa butter fats are made up predominantly by three major fatty acid molecules:

• palmitic acid,
• stearic acid,
• and oleic acid.

Oleic acid is unsaturated (has a double bond on its carbon chain), making it kinked and unable to pack well with other molecules. Because of this, a greater proportion of oleic acid in the fat results in a lower melting temperature for the cocoa butter.

Chocolate makers can adjust the amounts of each fatty acid to produce a chocolate that melts only in the mouth, giving it a superior quality.

Tempering Chocolate

The cocoa butter in chocolate can have several diferent crystal structures (three dimensional patterns in which the fat molecules pack).

There are six known chocolate crystal forms or polymorphs. You can obtain each form by varying the fatty acid ratios and the temperature at which the chocolate is tempered (cooled).

Only a few of the polymorphs with the right blend of snap (when you bite into the chocolate) and melting (when it warms up in your mouth) are considered ideal for gourmet chocolate. Melting is especially important because it controls how well the chocolate disperses and releases flavor onto your tongue.

Polymorph	Melting temperature	Properties
I	17°C	Soft, crumbly, melts too easily.
II	21°C	Soft, crumbly, melts too easily.
III	26°C	Firm, good snap, melts too easily.
IV	28°C	Firm, good snap, melts too easily.
V	34°C	Glossy, firm, best snap, melts near body temperature.
VI	36°C	Hard, takes weeks to form.

Sources consulted: Food Chemistry by Belitz, Grosh, and Schieberle, The Science of Chocolate by Beckett, and Wikipedia.