Instant coffee has been widely consumed for decades due to its convenience. During its peak popularity in the 1970s, nearly a third of roasted coffee imported into the United States was converted into instant products.

Today, about 15% of the world’s coffee is consumed in the form of instant coffee, whether at home, in the office or in a vending machine.

The main advantage of instant coffee is convenience. You can drink a cup of coffee as quickly as possible without using any equipment other than a cup.

At the same time, market researchers also found that consumers like simple coffee consumption patterns. Although brewing coffee by themselves is superior in taste and grade, they do not like the coffee grounds produced. Especially since the classification of garbage, a key issue now is: are coffee grounds considered wet garbage or dry garbage?

Some coffee drinkers are already very accustomed to instant coffee. Their consumption habits have been cultivated. An instant coffee manufacturer has conducted a test to distinguish the taste of freshly ground coffee and instant coffee. The results are surprising. The target audience is not so straightforward in judging the two.

And since the advent of instant coffee, practitioners have been improving instant coffee in various ways. For example, some early instant coffee powders were not easily soluble in water, leaving wet powder clumps floating in the cup, which made the aroma of coffee easily dissipate.

So manufacturers quickly developed a process that made a can of instant coffee smell like freshly ground coffee when opened, and more modern manufacturing processes make instant coffee granules look more like ground coffee beans.

Instant coffee is the fulfillment of a wish hundreds of years ago

The desire to have instant coffee by simply mixing liquid or dry concentrate with hot water dates back hundreds of years, with the first record of instant coffee appearing in England in 1771.

The first official instant coffee product was born in the United States in 1853, and was widely tested during the Civil War.

Coffee poster from the Civil War

In 1901, the first successful technology for making stable instant coffee powder was invented by Japanese Sartori Kato, whose process was derived from his technology for making instant tea.

Sartori Kato's patent in the United States

Coffee poster by Sartori Kato

Five years later, George Constant Washington, a British chemist living in Guatemala, developed the first commercially successful process for making instant coffee.

A poster about George Constant Washington Coffee

Washington's invention was called "Red E Coffee," and it dominated the U.S. instant coffee market for 30 years starting around 1910.

Red E Coffee

In the 1930s, the Brazilian coffee industry encouraged research into instant coffee as a way to absorb their excess coffee bean production.

By 1950, Borden researchers had devised a method for producing pure coffee extract without additional carbohydrates, an improvement that expanded the appeal of instant coffee to the general public.

Borden Company Advertisement

In 1963, Maxwell House began selling freeze-dried instant coffee granules that reconstituted into a beverage that tasted more like freshly brewed coffee. Over the next five years, all the major instant coffee manufacturers developed freeze-dried versions, and by the mid-1980s, 40% of instant coffee used in the U.S. was made with this technology.

Two beans share the world, Robusta makes instant coffee

Of the 50 known coffee bean species, two dominate the beverage coffee industry

Comparison of Arabica and Robusta coffee beans

Arabica coffee varieties, which are mainly grown in Latin America, India and Indonesia, have a strong aroma and are not prone to bitterness. They account for about 70% of the world's coffee production. Because they need to be picked by hand at the peak of maturity, their harvesting costs are relatively high.

Arabica coffee beans

Robusta coffee is mainly grown in Africa, India and Indonesia. Although its aroma is not as strong as Arabica, it is widely used in the production of instant coffee because of its low planting cost and stronger resistance to diseases and insects.

Robusta coffee beans

A cup of simple brewing instant coffee is made like this

The coffee beans are first roasted to release their flavor and aroma. Most roasting plants use a rotating cylinder with hot combustion gases. When the beans reach a temperature of 165°C, roasting begins. The whole workshop is filled with a popping sound similar to that when making popcorn.

Coffee beans take about 8-15 minutes to roast, but using a fluidized bed to roast coffee only takes 30 seconds to 4 minutes, which is about 25-75% of the efficiency of the above method. In addition, the fluidized bed can operate at a lower temperature, which can better preserve the aroma and flavor of the coffee beans.

The coffee beans are then ground using a scoring roller device to form small pieces ranging in size from 0.5 to 101 mm.

Softened water (water without inorganic salts) mixed with ground coffee beans first passes through several hot percolation columns (140-180°C) that operate at pressures above atmospheric pressure to extract hard-to-capture components such as carbohydrates.

It then passes through two or more percolation columns at a lower temperature (about 100°C) to extract the more flavorful elements. The extract is passed through a heat exchanger to cool it down to about 5°C. By the end of this cycle, the coffee extract contains about 20-30% solids.

After the filtration step, there are several ways to treat the extract from the previous process to increase its concentration to obtain an extract with approximately 40% solids.

1. The liquid is processed in a centrifuge to separate the lighter water from the heavier coffee extract;

2. Removing water by evaporation before cooling the hot coffee extract;

3. The extract is cooled enough to freeze the water, and then the ice crystals are mechanically separated from the coffee concentrate

One of the pleasures of drinking coffee is smelling its aroma. During several steps of the manufacturing process, volatile aromatic elements are lost and must be recovered in subsequent steps to produce attractive instant coffee products.

These volatile aroma elements can be recovered at several stages of the manufacturing process

1. It can collect the gases released during the roasting or grinding process. The ground and roasted coffee can be heated to release additional aromatic gases.

2. By passing water vapor or an appropriate solvent through the bottom of the fluidized bed, the roasted coffee can be stripped and the aromatic components captured;

3. By applying high pressure, aromatic oils can be obtained from coffee grounds;

4. Gas can also be distilled from coffee extract after the mixing process is completed

In order to retain as much aroma and flavor as possible, oxygen needs to be removed from the coffee extract, a process that is achieved by foaming the liquid with other gases such as carbon dioxide or nitrogen before the dehydration stage.

There are two basic methods used to convert liquid coffee extract into dry form. Spray drying is done at higher temperatures, which affects the taste of the final product, but is less expensive than freeze drying. The procedure is:

1. The cooled and clarified concentrate is sprayed through the nozzles at the top of the drying tower, which is 23 meters high. Air heated to about 250°C is blown downward through the mist to evaporate the water.

2. Air is discharged from the tower near the bottom and filtered to remove fine particles, which can be recirculated through the tower or reintroduced during the condensation process;

3. The dried coffee powder is collected at the bottom of the tower and then further processed. The resulting powder consists of free-flowing, dust-free particles containing 2-4% moisture.

Spray drying equipment

After spray drying, the powder can be formed into coarser particles in a step (this is achieved by exposing the powder to steam or fine mist while rolling it in the air). The agglomeration process of instant coffee mainly rewet the surface of the coffee powder particles, making the particles contact with each other, thus forming larger particles.

This step can also be replaced by freeze drying, a process that involves four steps, starting with "primary freezing", where the coffee extract is frozen into a paste at a temperature of about -6°C.

The pre-cooled extract is placed on steel belts, trays or drums and then further cooled in a series of steps until its temperature reaches -40°C

A fast cooling process (30-120 seconds) will produce a lighter colored extract with smaller particles, while a slower process (10-180 minutes) will produce a darker colored extract with larger particles.

The frozen extract is then broken up into chunks, ground into particles of the right size for the drying step, sieved to ensure the right size, and any particles that are too small are melted and returned to the primary freezing stage.

The frozen particles are fed into a drying chamber where, under appropriate heat and vacuum conditions, the water evaporates and is removed, and the volatile aromas recovered from earlier manufacturing steps are then sprayed onto the dry coffee particles.

Instant coffee granules are hygroscopic, that is, they absorb moisture from the air, so they must be packaged in moisture-proof containers under low humidity conditions to keep the product dry until it is purchased and opened by the consumer.

In addition, to prevent the loss of aroma and flavor, the product packaging is also filled with some gas, usually carbon dioxide or nitrogen.