A lot of people insist that instant coffee isn’t real coffee, but I’m afraid to say that it is. Despite what you might think of it, almost 50 percent of the world’s coffee is turned into instant, so I thought I’d let you in on how instant coffee is made.
Instant coffee is made by freeze-drying and spray-drying the concentrated extract of roasted coffee beans. After brewing, the water is removed by evaporation from the extract and frozen to create dry granules or powder. These granules stay in a solid state at room temperature and dissolve when combined with boiling water.
We’re going to take an in-depth look at the Nestlé factory in Derbyshire (UK) to see how their world-famous Necafé Gold instant coffee is produced through freeze-drying. Let’s look at the nine-stage process.
The nine stages of manufacturing instant coffee
Stage one: Delivery
Raw, green coffee beans enter the Nestlé factory by lorry up to four times a day. It takes more than two hours to unload the 27 tonnes of green coffee that are inside each of the four lorries.
The coffee is then sieved and cleaned by machine to remove any unwanted debris that may have found its way into the batch of beans.
Stage two: Roasting
Next comes the roasting of the beans to turn them from their original green colour to the more familiar brown. For Nescafé Gold, a blend of five different beans, weighing 420kg (926lbs) in total, is added to a giant roaster.
The beans are heated to 230°C (446°F) to produce a medium roast which, the company says, is great for drinking both with and without milk. After 10 minutes of roasting, the beans are then rapidly cooled to 40°C (104°F) to avoid further cooking from the residual heat.
Stage three: Grinding
The roasted coffee beans are now sent to be ground in an industrial roller-mill grinder. This is not the sort of grinder you’ll find on the home kitchen counter. It’s capable of grinding a staggering 1,500kg (3,300lbs) of coffee per hour.
When coffee is ground, a lot of the aromas are lost into thin air. To minimize the loss, the aromas are collected by pumping nitrogen gas through the grounds, capturing the aromas on its way through. The vapour is then stored in a tank to be added later on.
Stage four: Brewing
Now comes the bit you’ll recognize. The ground coffee is now mixed with water to brew, much like you would do at home using a French press (cafetière).
However, this isn’t just a couple of scoops for your six-cup cafetière. Almost 700kg (1,543lbs) of coffee is brewed in a giant extraction pod, enough to produce an incredible 250,000 cups of coffee.
Interestingly: the spent coffee grounds are not thrown away at the Nestlé factory. Coffee grounds produce the same amount of energy as coal, so they are dried and burned in the boilers to power the factory. Something you might want to give a go if you have a log burner at home.
Stage five: Evaporation
Now we start to see the transformation into instant coffee. The brewed and filtered coffee is sent to a giant evaporation tank that spans the entire six floors of the Derbyshire factory. The tank holds around one million cups of coffee, enough for even the most hardened of coffee drinkers!
Every hour, 30,000 litres (6,600 gallons) of coffee is moved through pipes inside the evaporator. Warmed to 70°C (158°F), the water evaporates and is siphoned off.
The coffee is condensed by 50 percent to produce a thick, syrupy coffee extract. This is much like you would reduce a stock at home. As you heat the liquid stock, it reduces and intensifies in flavour.
Stage six: Freezing
The coffee extract is then pre-chilled through heat exchangers in preparation for freezing. Once successfully chilled, the syrupy coffee extract is poured onto a conveyor belt that makes its way into a giant freezer with temperatures between -40°C and -50°C (-40°F and -58°F). That’s colder than the north pole.
The coffee is then broken up into granules. These deep-frozen granules still contain water which needs to be removed.
Stage seven: Sublimation
Stacked up in trays, the granules are driven through a low-pressure tube for several hours to undergo sublimation. Sublimation is the process of turning a solid into a gas without passing through the intermediate liquid phase.
If the coffee were to be turned into a liquid again, the remaining aromas would be released and lost. Sublimation is achieved by heating the coffee to 60°C (140°F) in a strong vacuum. Under pressure, the frozen water vaporizes and turns directly into steam.
When the coffee granules exit the vacuum, they have successfully been dried with the aromas locked in. The granules will now stay in a solid state when stored at room temperature.
Stage eight: Lost aromas readded
The coffee granules are now collected, and the aromas that were captured earlier with nitrogen gas are readded. The aromas are sprayed over the granules as they pass through into giant sacks.
Stage nine: Packaging
The freeze-dried coffee is now ready to be placed into jars. A conveyor belt of empty glass jars are each filled with coffee in under a second. Each jar is topped with a lid containing an airtight seal and a Necafé label is attached.
Packaged with cellophane in sixes, the cases are then sent all over the world, even to coffee-producing countries such as Peru.
Spray-drying coffee is less common than freeze-drying but is sometimes preferred for its large scale, economic benefits to production.
A pulse combustion spray dryer releases liquid coffee which is blown at around 400mph (644km/h) by hot air measuring 538°C (1000°F) in temperature.
The high-velocity air instantly atomizes the liquid with the intense heat driving off the water, forming a powder that exits at the bottom of the dryer.
The turbulence of the atomization zone inside the dryer is so powerful that it makes for almost instantaneous drying with no scorching due to evaporative cooling.
Despite being a cheaper way of producing instant coffee, the enormous loss of aromas in the spray-drying process results in an inferior tasting product.
The history of instant coffee
The first soluble instant coffee was invented in 1899 by David Strang of Invercargill, New Zealand. Until recently, Japanese chemist Satori Kato was wrongly credited with the invention with his version in 1901.
Before 1899, there were several incarnations of a form of instant coffee, but nothing like we would recognize today. Starting in 1771 in Britain, this was called a coffee compound and even received a patent from the British government.
Next came an American version created in 1851. Used during the American Civil War, “cakes” of instant coffee were rationed to the soldiers and proved to be extremely popular for morale.
Instant coffee gained further traction when British chemist, George Constant Louis Washington, helped to commercialize Satori Kato’s coffee through his work in Guatemala.
However, George Washington coffee was viewed somewhat as a novelty and people didn’t much enjoy the taste. Tweaks were also needed as the coffee didn’t dissolve very well, adding to its unpopularity.
Things really took off when Nestlé got involved in 1938. Having been approached by the Brazilian Coffee Institute in 1930, Nestlé was asked to create a flavoursome, soluble coffee using Brazil’s huge surplus of coffee both to decrease spoilage and boost the Brazilian economy.
Nestlé agreed and spent the next seven years working on an instant coffee that delivered in both its flavour and its solubility.
The breakthrough came in 1937 when Nestlé scientist Max Morgenthaler invented a new method for producing soluble coffee using dried coffee extract together with soluble carbohydrates.
Production began the following year and became the first version of the product we all know today as Nescafé. The new instant coffee was an instant success and again proved to be extremely popular amongst the soldiers of World War II.
Attempts to improve the Nescafé product were made in the 50’s and 60’s by removing the use of carbohydrates to stabilize the coffee, with focus on producing a more pure product.
A method called agglomeration, which was achieved by steaming coffee granules to make them stick together in clumps, was used in place of carbohydrates. However, further heating through the brewing process worsened the coffee’s flavour and so Nestlé needed to look to other ideas.
The final breakthrough came with the advent of freeze-drying coffee. The freeze-drying process is considered the best for quality when it comes to instant coffee and is therefore still used by Nestlé for their Necafé coffees today.