Unwrapping the secrets of chocolate

Sacred or sensual, sex-aid or salve, how did the seed of a tropical tree so completely capture mankind’s imagination? Ashley Hay investigates the chemistry between us and our favourite food.

Frank Bean

The Aztec emperor Montezuma consumed it before visiting his harem; the Marquis de Sade employed it in his vile schemes; Madame de Pompadour, influential chief mistress to Louis XV, used it as an aphrodisiac; on reaching the summit of Everest, Tenzing Norgay buried a small piece in the snow as an offering to the gods. And it’s one of the first foods NASA hopes to “print”.

There’s nothing quite like chocolate. For millennia we’ve worshipped it, craved it and been seduced by it. Now, science is starting to unravel its secrets.

On a Saturday afternoon 20 of us have gathered to learn about chocolate in a workshop at Kimberley Chocolates in Leichhardt, Sydney. It’s a sparse room with stainless steel benches, sinks, vats and ladles. Beneath the window sits a metal tub, a barred tray to one side, a wheel and spout to the other, and a thermostat clicking up to 37˚C as the machine begins to work. The device, made in Holland by J.K.V. de Chocoladevormenspecialist, is designed to melt and keep chocolate in sweet perpetual motion, smooth and malleable. Our flesh and warmth seem soft and incongruous amongst the machinery and stainless steel. There is a delicious correlation between chocolate and people: it melts at our body temperature, 37˚C, and I’m not the first person to wonder if this might partly explain our fascination with it.

Leading the class is Joseph Atallah, the Kimberley chocolatier – an ebullient middle-aged food scientist with a Lebanese heritage. He arrived in the business by way of organic chemistry and “a little personal interest”. “Any milk chocolate I bought, I never liked,” he says. He wondered about making something better. Differences in taste and quality, he tells us, come down to the source of the beans – Atallah prefers the stronger flavour of West African to the Asian and Central America beans – and to mysterious-sounding techniques such as “conching” and “tempering”. “A fine chocolate is conched, or ground, so that our tastebuds can’t distinguish its particles,” he explains.

Traces of cacao have been found in clay pots, lying on piles of bones from the dismembered bodies of sacrificial victims

Even Carl Linnaeus, the 18th century father of taxonomy, fell under the spell of chocolate. He classified the cocoa tree as Theobroma cacao. The genus name, Theobroma, means “food of the gods”.

While the trees originated in Ecuadorian forests at the headwaters of the Amazon, today they grow around the world in a precise 20-degree band – from 10˚S to 10˚N. They’re beautiful, with large glossy leaves and rugby ball-shaped pods that can take on a rainbow of colours from greens through yellows to warm oranges and bright scarlet. Cut open the leathery pods and there, in a white sticky fibrous pulp, lie 40 or so reddish-brown oval seeds that look like oversized almonds.

The cocoa beans are encased in the pod in a sweet pulp. – ISTOCK

Since ancient times, these beans have been associated with the sacred. At a 4,000-year-old burial site called San Lorenzo in the capital of the Olmec empire (now part of the Mexican state of Veracruz), traces of cacao have been found in clay pots. These, Terry Powis and colleagues reported in Proceedings of the National Academy of Science in 2011, lay on piles of bones from the dismembered bodies of sacrificial victims.

Cacao remained integral to the mythology of later Mesoamerican civilisations, such as the Mayans. Their paintings, preserved in a book called the Madrid Codex, depict priests lancing their earlobes, chests and genitalia, and collecting the blood into cups; glyphs tell us that these pots contained cacao.

Mesoamerica was steeped in chocolate. An Aztec statue shows a man holding a cocoa pod. – WIKI COMMONS

It was equally sacred to the Aztecs. Montezuma served a chocolate drink in a golden cup to Hernando Cortez, a being he mistook for the bird god Quetzalcoatl. The Spanish conquistador landed his white-winged tall ships on the Mexican coast in April of 1519, the very month and year that the Aztec priests are said to have predicted their bird god would return – if true, one of the greatest coincidences in history. According to Bernal Diaz del Castillo, a soldier in Cortez’s army: “They brought some in cups of fine gold, with a certain drink made of the cacao itself which they said was effectual to produce lustful desires toward women … then they brought in some 50 jars of good cacao with its froth and they drank it, the women serving them with a great deal of respect and when [Montezuma] did eat, several Indians stood by him and danced before him, Montezuma being much given to pleasure…”

The cacao bean was not just for religious or aphrodisiac use. In those days money really did grow on trees. “Every native American group from Mexico, south to Venezuela and into Colombia used it as a form of currency,” says Lou Grivetti, a geographer from the University of California, Davis. He spent more than a decade studying the history of chocolate with a grant from the Mars company. In those days, 10 beans could buy a rabbit, 100 a slave. The bean was entrenched in the spiritual, nutritional and financial fabric of life in the region. According to Grivetti, all Mesoamerican languages have words for cacao; the most ancient of them use 30-40 terms for the bean. The English word cocoa and the Spanish cacao both derive from a Mesoamerican word, kakawa.

The drink “would have been extremely bitter, like a double or triple espresso.”

Thanks to the accounts of the Spanish conquistadors, we know that Montezuma served Cortez real chocolate – a buttery bean extract dissolved in hot water – although at the time Cortez cared much more for the gold cup than what was in it. The drink “would have been extremely bitter, like a double or triple espresso,” says Grivetti. The conquistadors were, however, clearly impressed by its purported Viagra-like properties.

We know that the Aztecs were drinking a cacao bean extract, but we cannot be sure what earlier civilisations were imbibing. The evidence of cacao found in ancient pots at the Olmec capital and at 3,000-year-old sites in Honduras comes from traces of theobromine, a long-lasting chemical only found in the cacao plant in this part of the world. But archaeologists John Henderson and Rosemary Joyce from the University of California, Berkeley, who worked the Honduran site, suspect that theobromine was not a residue of beans but of a fermented alcoholic product of the slightly sweet pulp that encases them. The shape of the flasks, with very narrow spouts, seem more suited to pouring an alcoholic beverage than the frothy viscous chocolate that Montezuma drank. In the tropics, fermentation of the pulp would have happened all too easily. And the alcohol-induced trances might have been appreciated by both the priests and the sacrificial victims who were given the brew.

It takes a complex process to transform the beans of T. cacao into modern “chocolate”. The transition of the food of the gods from beer to a buttery ooze was just the beginning of a long history of tinkering. The beans and pulp were scooped from the pods and left in a pile to ferment for several days; then they were dried and roasted. Roasting also cracked the beans; the shells were winnowed away and the inner seeds, or “nibs”, were ground into paste. As Cortez discovered, the taste was oily and very bitter. Many of the conquering Spaniards dismissed the brew as “a drink for pigs”. But others played with the flavour, retaining the vanilla that the early Mayans chocolatiers had used, and adding cinnamon and other sweeteners.

Montezuma served Cortez chocolate after their first fateful meeting. – HISTORICAL PICTURE ARCHIVE/CORBIS

The first beans arrived in Spain in 1544, and from there spread throughout Europe.

For many years, chocolate was consumed as a fatty drink, a major competitor to tea and coffee. Then in the 1820s a Dutch father and son tinkered with cacao chemistry and laid down the innovations for the chocolate bar. Casparus van Houten, whose cacao mill first started grinding in Amsterdam in 1815, patented a process where he fed ground cacao paste into a hydraulic press and the fatty yellow cocoa butter oozed out and drained away. The remaining cacao powder offered a more palatable drink for those who didn’t care for all that fat. His son, Coenraad Johannes, did some more tinkering, treating the powder with alkaline salts to make it more soluble – a process now known as “Dutching”.

Once the van Houten patent expired, others were free to do more experimentation. In 1847 the British chocolate maker J.S. Fry added a little cacao butter back to the cacao powder, along with sugar, and invented a product that could be shaped, poured and moulded to make the world’s first commercial chocolate bar.

But it wasn’t the first time the word “chocolate bar” entered the lexicon. We know that thanks to the writings of the Marquis de Sade. Some academics suggest the marquis was almost as notorious for his use of chocolate as for the sadistic behaviour he gave his name to. Grivetti has uncovered a reference to a chocolate bar in a letter de Sade wrote to his wife while imprisoned in 1779. Dated May 16th, he chastised her for sending him cookies with “fake” chocolate in them. “The next time you send me a package … try to have some trustworthy person there to see for themselves that some chocolate is put inside. The cookies must smell of chocolate, as if one were biting into a chocolate bar.”

Chocolate was the Marquis de Sade's most acceptable vice. – ADOC-PHOTOS/CORBIS

Barbara Lekatsas, a professor of literature at Hofstra University in New York, found another reference to de Sade’s penchant for chocolate in the secret memoir of Bachaumont dated 25 July 1772. De Sade “gave a ball to which he invited many people and for dessert gave them very pretty chocolate pastilles. They were mixed with powdered Spanish fly. Their action is well-known. All who ate them were seized by shameless ardour and lust and started the wildest excesses of love. The festival became a Roman orgy.”

Ahem. Nevertheless, the 1800s heralded many of the innovations that produced the chocolate we know and love today.

In 1876 milk chocolate was born when Swiss chocolatier Daniel Peter added Henri Nestlé’s evaporated milk powder, first produced 10 years before, to cacao. Three years later his compatriot Rodolphe Lindt discovered the benefits of “conching” – kneading, churning and stirring the cacao paste as it is recombined with cacao butter.

Conching – along with the controlled heating and cooling called tempering – transforms the food from a fairly brittle and rough texture to something smooth and velvety that also snaps delightfully when you break off a square.

Fermenting piles of cocoa beans are the first step to making chocolate. – ISTOCK

At Kimberley Chocolates on this Saturday afternoon, Atallah moves around the class, testing, re-rolling, distributing moulds and bowls of cocoa powder and crushed nuts.

“I used to try and get behind the science of chocolate at the beginning of these classes, thinking everyone would be as enthralled as I was,” he says. “Now I wait, I feed you a little chocolate, I wait until it gets your endorphins flowing, and then I explain. That feeling you get when you’re falling in love, that feeling of euphoria; that’s the brain releasing phenylethylamine."

Phenylethylamine triggers the release of norepinephrine and dopamine in the brain – as do amphetamines.

The food of the gods is packed with hundreds of different chemicals. Some are tantalising candidates for the properties attributed to chocolate: the cravings we have for it; the euphoria it creates and its supposed health benefits. Caffeine is present in small quantities. Another stimulant, theobromine, is present in greater quantities but has weaker effects on the the central nervous system (though not for dogs; for them chocolate can be dangerous because they don’t have the enzymes to break it down).

Phenylethylamine, the chemical Attalah noted for its association with the “feeling of falling in love”, triggers the release of norepinephrine and dopamine in the brain – as do amphetamines.

Attalah must have been harking back to the “chocolate theory of love” first hypothesised by New York psychiatrist Michael Liebowitz in his 1983 book The Chemistry of Love. In a 1980 interview with The New York Times, he speculated that the heartbroken might be relying on phenylethylamine in chocolate to replace the frisson of passion.

But chocolate and the love molecule was so 1980s. Today what you are much more likely to hear is that chocolate is very good for you.

The chemical and medicinal attributes of the cacao bean are far from our minds in Joseph Atallah’s back room. Perhaps Fernand Pessoa, the early 20th century Portuguese poet, had the best sense of it. “Look,” he wrote, “there’s no metaphysics on earth like chocolate.”

Those Mayan gods knew what they were doing.

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