The Science of Chocolate

What is Chocolate?

• There are three main types of chocolate: dark, milk, and white.
• Ruby chocolate exists but isn't officially recognized.
• All chocolate is made from the Theobroma cacao plant.
• Theobroma means "food of the gods."
• Cacao is derived from indigenous Mesoamerican names.
• For anything to be called "chocolate", it must contain cocoa solids.
• Cocoa solids include cocoa butter and pure cocoa particles.
• Many chocolates include other flavorings, fillings, or toppings.

Cacao vs Cocoa

• Cacao refers to the pods and beans before processing.
• Cocoa refers to the processed cacao bean product post fermentation, drying, roasting and refinement.
• Unprocessed cacao beans are astringent, bitter, and lack aroma.
• Processed cocoa powder is rich and very aromatic.

Types of Chocolate

• Dark chocolate: Contains cocoa solids, does not have milk content.
• Milk chocolate: Contains milk solids and is sweetened.
• White chocolate: Contains cocoa butter and sugar.

Benefits of Chocolate

• Contains polyphenols (flavonols) that may provide anti-blood clotting, anti-inflammatory, and antioxidant activity.
• Theobromine acts as a mild stimulant
• Eating chocolate releases endorphins resulting in a happiness feeling

Eating Chocolate

• All chocolate contains cocoa butter, which melts at 31-34 °C.
• It's best enjoyed slowly in the mouth, allowing it to melt.
• Melting releases aromatic molecules, enhancing enjoyment.

Chocolate-Making Process

• Chemistry takes place from cocoa bean to final chocolate bar.
• Steps include flavor precursor development, fermentation, roasting, and tempering.
• The image provided shows a flowchart of key stages of chocolate production from cacao pods to the final product.

Making Chocolate - Cacao Pods

• Harvested cacao pods are split open, the beans and pulp are piled.
• Sugary pulp ferments; yeasts convert sugars to alcohol.
• When oxygen is depleted, lactic acid bacteria take over.
• Aeration leads to acetic acid bacteria production.
• Heat and acids kill the beans.
• Fermentation produces flavor precursors, including amino acids.

Making Chocolate - Drying

• Cacao beans are dried to about 7% moisture to prevent microbial growth.
• Slow drying at low temperatures avoids acidic taste.
• Fermentation and drying occur at the place of harvest.

Making Chocolate - Roasting

• After drying, beans are delivered to chocolate processors and roasted at 110-150 °C.
• The Maillard reaction generates flavorful compounds, reducing acidity.
• It does not generate bitter compounds or remove new aromatic ones.

Making Chocolate - Grinding

• Roasted beans are cracked and nibs are ground into cocoa liquor.
• Cocoa liquor contains cocoa butter (55%) and cocoa particles.
• Particles must be <30 µm to avoid grainy texture.
• Cocoa butter can be separated into cocoa butter and cocoa powder.

Making Chocolate - Conching

• Cocoa liquor is rough, bitter, astringent, acidic, and viscous.
• Maker adds extra cocoa butter, sugar, milk solids, and flavorings like vanilla.
• Conching mixes ingredients for 8-24 hours.
• This process mellows the flavor, breaks particles, and coats them with cocoa butter.

Making Chocolate - Making Bars

• Conched chocolate is tempered and poured into molds to cool and solidify.
• Cooling causes slight shrinkage making it easy to unmold.
• This process greatly affects color, gloss, and texture.

Chocolate Flavor

• Chocolate has one of the most richest and complex flavors.
• Over 600 volatiles have been detected, a few of which account for the basic roasted quality.
• Bean's natural combination of sugars and proteins, as well as the preparation process gives rise to the complexity.

Most Prominent Tastes and Flavors

• Astringency and bitterness arise from phenolics and theobromine in the bean.
• Fruity, winey, sherry, and vinegary notes originate from the pulp.
• Almond, dairy, and flowery notes come from the self-digested bean.
• Roasted, nutty, sweet, earthy, flowery, and spicy notes develop from roasting.
• Sweetness and warmth come from sugar and spices like vanilla.
• Caramel, butterscotch, and cooked-milk flavors come from added milk solids.

Working with Chocolate - Melting

• Melting methods include directly over the stove, using a bain-marie, or in the microwave.
• Chocolate is a poor heat conductor, hence should be chopped into small pieces.
• Adding a little water to molten chocolate results in a stiff, unworkable mass due to sugars and cocoa particles binding the water.
• If adding liquid, add a large quantity all at once or by adding the chocolate to the liquid.

Working with Chocolate - Tempering

• Besides melting, tempering gives glossy chocolate when cooled.
• Tempering involves getting temperatures right to ensure the correct cocoa butter crystal form is formed.

Cocoa Butter

• Cocoa butter, like all fats, has a triacylglyceride structure.
• Over 95% of its fatty acids are oleic, stearic, and palmitic.
• Its simple structure is responsible for its narrow melting range.
• The structure of cocoa butter is such that oleic acid is usually in the middle of the triacylglyceride

What are crystals and different polymorphs?

• About 80% of cocoa butter is POP, POSt and StOSt, those being solids at room temp.
• The remainder 5-20% is POO and StOO, this being liquid at room temp.
• The triacylglycerides can crystallize in six different forms, known as Forms I-VI.
• Form V is the only crystalline form which gives correctly tempered chocolate.
• Cocoa butter is polymorphic (molecules can be stacked differently).
• There are 6 accepted polymorphs (forms), the desired polymorph is Form V.

Cocoa Butter and its relation to Packing

• The fat molecules can pack in two different ways, only Forms V & VI packing in triple-chain length packing.
• Triple-chain length packing creates a stable configuration.

Chocolate Tempering

• Tempering ensures a shiny and snappy finished product.
• Melting is the process where chocolate is melted then cooled down.
• It is important because cocoa butter is polymorphic.
• The crystals formed when cocoa butter is cooled can take various forms.
• Tempering involves melting the chocolate completely then cooling it in a controlled manner.

Working with chocolate – Tempering, Methods

• To properly temper the product, either heat, cool, and reheat or melt then seed.

Tempering Chocolate

• Tempering is related to the form of cocoa butter crystals.
• If melted chocolate is heated over the tempering temperature, this will melt the crystals.
• Or if the chocolate falls below the tempering temperature, this will form the other crystal forms.
• The chocolate then can be retempered any time.

Storing Chocolate

• Improper storage may form a white coating called bloom.
• Sugar bloom results from temperature changes, causing condensation to draw sugar to the surface.
• Fat bloom results from high-heat storage or fat crystal transitions.

What is fat bloom?

• Fat bloom makes the chocolate looks pale and patchy.
• If puts people off as it is very similar to mould.
• There is nothing mouldy about it.

Prevention of Fat Bloom

• Storing at the correct temperature. (not too warm)
• Temper appropriately.
• Selecting chocolate formulation with specialized fats.
• For a filled chocolate choose compatible fats, no/little liquid oils, and small amounts of non-compatible fats such as coconut oils.