10,000 years of innovation in every can

Every can of Coca-Cola is the product of centuries of accumulated human ingenuity. Here’s how it happens

 
Coca-Cola can on a pedestal
(Photo by Liam Mogan)

The H-E-B grocery store a mile from my home in Austin, Texas, sells 12 cans of Coca-Cola for US$4.49.

Each one of those cans originated in a small town of 4,000 people on the Murray River in Western Australia called Pinjarra—the site of the world’s largest bauxite mine. Bauxite is surface-mined—basically scraped and dug from the top of the ground—and then crushed and washed with hot sodium hydroxide until it separates into aluminum hydroxide and a waste material called “red mud.” The aluminum hydroxide is first cooled and then heated to over a thousand degrees Celsius in a kiln, where it becomes aluminum oxide, or alumina. The alumina is dissolved in a molten substance called cryolite, a rare mineral first discovered in Greenland, and turned into pure aluminum using electricity in a process called electrolysis. The pure aluminum sinks to the bottom of the molten cryolite, is drained off and is placed in a mould. The result is a long, cylindrical bar of aluminum.

Australia’s role in the process ends here. The bar is transported west to the port of Bunbury and loaded onto a container ship to begin a month-long journey to—in the case of Coke for sale in Austin—the port of Corpus Christi, on the Texan coast.

After the aluminum bar makes landfall, a truck takes it north on Interstates 37 and 35 to a bottling plant on Burnet Road in Austin, where it is rolled flat in a rolling mill and turned into aluminum sheets. The sheets are punched into circles and shaped into a cup by a mechanical process called drawing and ironing—this not only forms the can but also thins the aluminum. The transition from circle to cylinder takes about a fifth of a second. The outside of the can is decorated using a base layer called “urethane acrylate,” then up to seven layers of coloured acrylic paint and varnish, which are cured using ultraviolet light. The inside of the can is painted, too—with a chemical called a “comestible polymeric coating,” to prevent aluminum from getting into the soda. So far, this vast tool chain has produced only an empty can with no lid. The next step is to fill it up.

Coca-Cola is made from syrup produced by the Coca-Cola Company of Atlanta, Georgia. The syrup is the only thing the Coca-Cola Company provides; the bottling operation belongs to a separate, independent corporation called the Coca-Cola Bottling Company. The main ingredient in the syrup used in the United States is a sweetener called high-fructose corn syrup 55, so named because it is 55% fructose, or “fruit sugar,” and 42% glucose, or “simple sugar”—the same ratio of fructose to glucose as in natural honey. High-fructose corn syrup is made by grinding wet corn until it becomes cornstarch, mixing the cornstarch with an enzyme secreted by a bacillus, a rod-shaped bacterium, and another enzyme, this one secreted by an aspergillus mould, and then using a third enzyme, xylose isomerase, derived from a bacterium called Streptomyces rubiginosus, to turn some of the glucose into fructose.

The second ingredient, caramel colouring, gives the drink its distinctive dark brown colour. There are four types of caramel colouring; Coca-Cola uses type E150d, which is made by heating sugars with sulphite and ammonia to create a bitter brown liquid. The syrup’s other principal ingredient is phosphoric acid, which adds acidity and is made by diluting burnt phosphorus (created by heating phosphate rock in an arc furnace) and processing it to remove arsenic.

High-fructose corn syrup and caramel colouring make up most of the syrup, but all they add is sweetness and colour. Flavours make up a much smaller proportion of the mixture. These include vanilla, which is the fruit of a Mexican orchid that has been dried and cured; cinnamon, which is the inner bark of a Sri Lankan tree; coca leaf, which comes from South America and is processed in a unique U.S. government–authorized factory in New Jersey to remove its addictive stimulant, cocaine; and cola nut, a red nut found on a tree that grows in the African rainforest (this may be the origin of Coca-Cola’s distinctive red logo).

The final ingredient, caffeine, is a stimulating alkaloid that can be derived from the cola nut, coffee beans and other sources.

All these ingredients are combined and boiled down to a concentrate, which is transported from the Coca-Cola Company factory in Atlanta to the Coca-Cola Bottling Company factory in Austin, where it is diluted with local water infused with carbon dioxide. Some of the carbon dioxide turns to gas in the water, and these gas bubbles give the water effervescence, also known as “fizz,” after its sound. The final mixture is poured into cans, which still need lids.

The top of the can is carefully engineered: It is aluminum, too, but it has to be thicker and stronger than the rest of the can to withstand the pressure of the carbon dioxide gas, and so it is made from an alloy with more magnesium. The lid is punched and scored, and a tab opening, also made of aluminum, is installed. The finished lid is put on top of the filled can, and the edges of the can are folded over it and welded shut. Twelve of these cans are packaged into a paperboard box called a fridge pack, using a machine capable of producing 300 such packs a minute.

The finished box is transported by road to my local H-E-B grocery store, where—finally—it can be bought, taken home, chilled and consumed. This chain, which spans bauxite bulldozers, refrigerators, urethane, bacteria and cocaine, and touches every continent on the planet except Antarctica, produces 70 million cans of Coca-Cola each day, one of which can be purchased for about a dollar on some close-by street corner, and each of which contains far more than something to drink. Like every other creation, a can of Coke is a product of our world entire and contains inventions that trace all the way back to the origins of our species.

The number of individuals who know how to make a can of Coke is zero. The number of individual nations that could produce a can of Coke is zero. This famously American product is not American at all. Invention and creation, as we have seen, are things we are all in together. Modern tool chains are so long and complex that they bind us into one people and one planet. They are chains of minds: local and foreign, ancient and modern, living and dead—the result of disparate invention and intelligence distributed over time and space. Coca-Cola did not teach the world to sing, no matter what its commercials suggest, yet every can contains humanity’s choir.

Once we knelt by a stream to scoop water with bare hands. Now we pull a tab on an aluminum can and drink ingredients we cannot name from places we may not know mixed in ways we do not understand.

Coca-Cola is a branch on our 50,000-year-old tree of new. It is there because water is our most important nutrient. If we do not drink water, we die within five days. If we drink the wrong water, we die of water-borne diseases like cyclosporiasis, microsporidiosis, coenurosis, cholera and dysentery. Thirst should limit us to places within a day or two’s walk of potable water and make migration and exploration dangerous. But the 2,000 generations developed tools to make water portable and potable, and allow us to live far away from rivers and lakes.

Early technologies for carrying and storing water included skins, hollowed gourds called calabashes and—18,000 years ago—pottery. Ten thousand years ago we developed wells, which allowed constant access to fresh groundwater. Three thousand years ago, people in China started drinking tea, a step that coincided with drinking boiled water, a practice that—coincidentally—killed disease-bearing micro-organisms. The existence of these organisms was not discovered for another 2,500 years, but as the technology of tea spread gradually from China through the Middle East and eventually, around 1600 CE, to Europe, tea drinkers began to suspect that water was healthier when boiled. Boiling also enabled free-ranging travel, as water found along the way could now be made safe.

As bottles—first developed by the Phoenicians of the Middle East 2,500 years ago—became more common, it was at last possible to transport sacred water, with its healing purity and high mineral content, from springs to other places. Once bottled and transported, these “mineral waters” could also be flavoured.

Some of the earliest flavoured waters were Persian sharbats,or sherbets, made using crushed fruits, herbs and flower petals, and first described in Ismail Gorgani’s 12th-century medical encyclopedia, Zakhireye Khwarazmshahi. About 100 years later, people in Britain drank water mixed with fermented dandelions and the roots of the burdock plant, which made it effervescent. Hundreds more years later, similar drinks were made in Asia and the Americas, using parts of a prickly Central American vine called sarsaparilla or the roots of sassafras trees. All of these variants on the theme of sparkling water and drinks made with natural ingredients were thought to have health benefits.

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In the late 1770s, chemists began to replicate the properties of spring water and herbal drinks. In Sweden, Torbern Bergman made water effervescent using carbon dioxide. In Britain, Joseph Priestley did the same. Johann Jacob Schweppe, a Swiss German, commercialized Priestley’s process and started the Schweppes Company in 1783. The mineral content of spring water was replicated with phosphate and citrus to make drinks called orange or lemon “phosphates,” or “acids”; these terms were popularly used for flavoured effervescent water in the United States into the 20th century.

As mineralization and carbonation became common, the healing properties associated with spring water receded in favour of remedies and tonics that contained exotic ingredients, such as the fruit of the African baobab tree and roots supposedly extracted from swamps. Many of these “patent medicines” contained cocaine and opium, which made them effective in treating pain (if nothing else) and also addictive.

One of these medicines, invented by chemist John Pemberton in Georgia in 1865, was made from ingredients including cola nut and coca leaf, as well as alcohol. Twenty years later, when parts of Georgia banned alcohol consumption, Pemberton made a non-alcoholic version, which he called “Coca-Cola.” In 1887, he sold the formula to a drugstore clerk named Asa Candler.

A few years earlier, Louis Pasteur, Robert Koch and other European scientists had discovered that bacteria caused disease, marking the beginning of the end for remedies and tonics. During the next two decades, medicine became scientific and also regulated. Harvey Washington Wiley, chief chemist at the U.S. Department of Agriculture, led a crusade that culminated in the signing of the Pure Food and Drug Act in 1906, and the creation of the agency that became the U.S. Food and Drug Administration.

In retreat as a medicine, Coca-Cola syrup was mixed with carbonated water in drugstores and sold as a beverage, its health claims softened to ambiguous adjectives such as “refreshing” and “invigorating.” At first, the carbonated water was added manually, and the drink was available only at soda fountains. Bottling was such a foreign idea that, in 1899, Candler licensed the U.S. bottling rights, in perpetuity, to two young lawyers for one dollar, because he thought that all the money in cola would come from selling the syrup.

This may seem like an amazing mistake, but in 1899 things weren’t so obvious. Glass was not easy to mass-produce, and Candler might have assumed that bottling would be a small business forever. But glass and bottling technologies were improving. In 1870, Englishman Hiram Codd developed a soda bottle that used a marble as a stopper—an ingenious approach that took advantage of the pressure from the carbonation to push the marble up the neck of the bottle to form a seal. Today, these Codd bottles sell at auction for thousands of dollars. As bottle technology improved, Coca-Cola bottling increased. Ten years after Candler sold his bottling rights, there were 400 Coca-Cola bottling plants in the United States. Coca-Cola, once tied to the soda fountain, had become portable, and it would soon migrate again, from the bottle to the can.

The story of the can begins with Napoleon Bonaparte. Napoleon, having lost more soldiers to malnutrition than to combat, had concluded that “an army marches on its stomach.” In 1795, the French revolutionary government offered a 12,000-franc prize to anyone who could invent a way to preserve food and make it portable. Nicolas Appert, a Parisian confectioner, spent 15 years experimenting and ultimately developed a method of preserving food by sealing it in airtight bottles then placing the bottles in boiling water. As with water for tea, the boiling killed bacteria—in this case, the bacteria that caused food to rot, a phenomenon that would not be understood for another 100 years. Appert sent sealed bottles that included 18 types of food, ranging from partridge to vegetables, to soldiers at sea, who opened them after four months and found unspoiled, apparently fresh food inside. Appert won the prize, and Napoleon awarded it to him personally.

France’s enemy, Britain, viewed Appert’s preservation technology as a weapon. Preserved food extended Napoleon’s reach. The army that marched on its stomach could now march further. Britain’s response was immediate: Inventor Peter Durand improved upon Appert’s approach by using cans made of tin instead of bottles. King George III awarded him a patent for his invention. Whereas glass bottles were fragile and difficult to transport, Durand’s cans were far more likely to survive the march to war. Canned food quickly became popular among travellers. It helped fuel the voyages of German explorer Otto von Kotzebue and British admiral William Edward Parry, as well as the California gold rush—which started in 1848 and saw 300,000 people move to California, establishing San Francisco as a major city in the process—and it extended the range of both armies in the American Civil War.

In a coincidence that nods to Napoleon and the origins of canning, Coca-Cola developed the first soda cans during the 1950s to supply American soldiers fighting a distant war in Korea. They were manufactured from tin that had been thickened to contain the pressure of carbonation and coated to prevent chemical reactions, steps that made them heavy and expensive. When cheaper, lighter aluminum cans were invented in 1964, Coca-Cola’s bottlers adopted them almost immediately.

Coca-Cola exists because we get thirsty. It exists because water can be dangerous, and we cannot all live next to a spring. It exists because people got sick and hoped that herbs and roots and tree bark from far-off places might help them. It exists because we sometimes need to travel—to flee, hunt, go to war or search for better places and ways. Coca-Cola may look like a luxury, but it exists because of a need for life.

Kevin Ashton led pioneering work on radio frequency identification (RFID) and co-founded the MIT Auto-ID Center. This article is adapted from his book, How to Fly a Horse (Doubleday, $33), published in January.

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