Chocolate Coated Science Booklet

Beans could be exchanged for a range of things including food, clothing, labour and even for paying fines!

This practice continued into the nineteenth century within the tribes of Mexico and Central America.

Sir John Eric Sidney Thompson, a 20th century English archaeologist and ethnographer, even described paying porters 20 cocoa beans per trip when he lived in Yucatan.

Milk and white chocolate have other ingredients added during the manufacturing process like animal fats, proteins, sugar and milk. In fact, one bar of milk chocolate contains 22 teaspoons of sugar! They also contain less cocoa powder, which is the source of good antioxidants in chocolate. This makes dark chocolate better for you than milk or white chocolate.

FACT: White chocolate does not contain ANY cocoa powder. Instead it just has cocoa butter and powdered or condensed milk, making it soft.

Method 1. Break the chocolate into pieces, and melt in a glass bowl over simmering water.

2. Whip the cream until soft peaks form.

3. Fold the two together to form a marble effect. Don’t over mix.

4. Transfer into a glass or bowl and chill.

Ingredients 75g dark chocolate 200ml double cream, whipped An easy and light chocolate dessert.

Chocolate marbled mousse for one

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Each big bright orange or yellow pod on the Theobroma cacao tree contains between 20-60 beans surrounded by pulp.

Cocoa beans were once used as money. The ancient Aztec culture prized cocoa beans so much that they used it as their currency.

The darker the better!

Great served with berries, extra whipped cream and a sprinkle of flaked chocolate.

Picture courtesy Memekiller

The starting point of chocolate, the cocoa bean, actually tastes nothing like chocolate. Cocoa beans taste more like a tropical fruit, with an aroma-less, bitter flavour.

The beans only begin to develop chocolate flavours after they have been fermented.

Money does grow on trees!

This booklet was produced in association with the University of Melbourne.

It starts with a fruit

1

Fermentation

Fresh beans and pulp are scooped from cacao pods, covered and left outdoors for 5-8 days to ferment. This begins the development of yummy chocolate flavours! The farmers then wash, dry and pack the beans, and send them to factories.

The whole beans are roasted for 30-60 minutes at 120-160°C, until they just start to crack. This produces molecules with strong, pleasant aromas, which are generally brown.

The Science:

The Science:

Yeast and bacteria from the environment ferment the pulp, producing ethanol, lactic acid and acetic acid. These compounds seep into the beans, break open the cell walls and make them sterile. The bean’s digestive enzymes then break down its energy sources, carbohydrates and proteins, into their building blocks- simple sugars and amino acids.

Roasting causes a chemical change in the beans. This is called the Maillard reaction, which occurs when amino acids and sugars combine. The Maillard reaction happens whenever foods rich in proteins (made of amino acids) and carbohydrates (made of sugars) are cooked above 140°C.

Important Molecules: Lactic acid FACT: 100g of dark chocolate contains as much caffeine as a cup of coffee!

3

Grind and Conch

The beans are cracked into smaller nibs, then ground, shelled and pulverised by steel rollers to form cocoa liquor. This is non-alcoholic and can be ground further to produce chocolate.

The Science:

2

Roasting

Acetic acid

Lactic and acetic acid are found in both yoghurt and chocolate. They are produced when bacteria ferment sugars.

4

Cool and Temper

For chocolate to be hard, glossy and have a long shelf life, the fat molecules must arrange correctly through tempering.

The Science

Grinding breaks down protein, fibre and starch particles in the nibs, until they’re too small for the tongue to detect- about 0.02mm.

The result is cocoa liquor, which is solid below 30°C and has 40-55% fat.

Dark chocolate is held at 29-30°C for about 5 minutes. This causes the fat molecules to move into a stable arrangement, thickening the chocolate. It’s then heated another 2°C, melting any remaining molecules that are wrongly arranged. It is then cooled and set.

Sugar is added to the liquor and heated to 45-80°C, forming a paste. It’s then agitated and smeared against a hard surface, called conching, for 8-36 hours. The heat evaporates some bad flavour molecules like acetic acid and ethyl acetate (nail polish remover).

Important Molecule: Triglycerides These are the most important component of fats, including cocoa butter. The long carbon chains in these molecules align during tempering, creating a hard, glossy finish.

Important Molecule: 2-acetylpyrroline This aroma chemical is found in freshly made toast, roasted coffee and steak.

Mmm, smells good right? Your nose can detect as little as a billionth of a gram of this molecule!

5

Eat!

Now we come to the best step: eating! Good, dark chocolate is a very rich source of antioxidants; important for our health as they stop or repair damage caused by free radicals.

The Choccy Buzz Chocolate contains the stimulants theobromine and caffeine. Together they create a characteristic ‘buzz’ when eating chocolate. They may also contribute to chocolate’s reputation as an aphrodisiac!

FACT: Theobromine is safe for humans in small doses, but can cause heart attacks in dogs and cats!

Important Molecules: Theobromine (stimulant) Epicatechin (antioxidant)

Cocoa butter (fatty substance) and lecithin (helps sugar to dissolve fat) are added towards the end for lubrication.

Important Molecule: Vanillin Vanillin can be added to chocolate at this stage. It’s the main scent molecule in vanilla extract, but is also in red wine, coffee, olive oil, butter and even raspberries.

FACT: Does your chocolate ever go white? If you heat and cool chocolate too quickly, you disrupt the stable arrangement created during tempering. This causes a white fatty bloom on the surface.

Are you ‘addicted’ to chocolate? Theobromine and caffeine are from the same family of chemicals as nicotine and morphine.