Instant coffee, also calledsoluble coffee, coffee crystals, and coffee powder, is a beverage derived from brewed coffee beans that enables people to quickly prepare hot coffee by adding hot water or milk to the powder or crystals and stirring. Instant coffee is commercially prepared by either freeze-drying or spray drying, after which it can be rehydrated. Instant coffee in a concentrated liquid form is also manufactured.

best freeze dryer

Advantages of Freeze drying

Freeze-drying is a process used in food processing to remove water from foodstuffs, with the goal of increasing their shelf life. The process consists of various steps: At first product temperature is lowered, usually to about -40°C, thus causing freezing of the free water. Later, the pressure in the equipment is lowered and sublimation of the frozen water occurs (primary drying). Finally, the bound water is removed from the product, usually increasing product temperature and further decreasing the pressure in the equipment, thus reaching the target value of residual moisture (secondary drying).

When processing foodstuffs the very low operating temperatures and the gentle drying conditions of a freeze-drying process avoid aroma and colour deterioration, as well as nutrient degradation, thus making this process particularly suitable for obtaining high quality products.

Freeze Drying Coffee

Process of Freeze Drying Coffee

Freeze-drying is a key stage in instant coffee production. Coffee beans are first roasted and ground, then dissolved into hot water. By this process coffee flavour, aroma and colour are extracted from the coffee grounds, and a highly concentrated liquor is obtained (generally the coffee solution is about 15–30% coffee by mass at the end of this extraction process).

After filtration, the coffee extract is dried to get the solid soluble coffee. The liquor is frozen to about -40°C to form a thin layer that is then broken into tiny pieces. These granules are then loaded into the freeze-dryer: both batch and continuous plants are used to freeze-dry the frozen product. A batch process is used for low capacities (generally ranging from 50-7,000kg of powder per day), while a continuous process is used for large capacities (generally ranging from 7,000-25,000kg of powder per day).

home freeze dryer machine

Instant Coffee: Spray Dried vs. Freeze Dried, What’s the Difference?

Spray drying

When you’re looking at instant coffee at your local supermarket, chances are you’re looking only at spray dried coffee. It’s, by far, the more common instant coffee creation process.

In this method, coffee beans are brewed and reduced to a thick concentrate. This concentrate is then sprayed as a mist in a chamber filled with swirling hot air (400-500 degrees F). The heat rapidly evaporates the water from the concentrate, causing the coffee to fall to the floor in dry clumps.

This process is pretty fast and can be done using huge machines with high output. When you compare the speed of spray drying to freeze drying, it’s no wonder why giant coffee companies prefer this one.

However, there is a major drawback. Applying that insane heat to the coffee concentrate destroys the flavor. The coffee aromas evaporate and disappear and the chemical structure of the coffee itself is changed, hurting the flavor.

In fact, this process eliminates so much flavor that most companies using this method have to capture the aromas from other pre-ground coffee and insert them into the instant coffee package. The aromas you smell when you open up an instant coffee package aren’t even from that coffee—they were artificially shot into the bag and evaporate away as soon as they’re exposed to oxygen.

The industry standard of spray drying is generally a quality-killing process. When our founders, Kalle and Josh, were getting started, they knew they had to find another way.

Freeze drying

The second method for creating instant coffee isn’t one that’s used by many coffee companies in the United States. It’s a little more common in parts of Europe, but by and large, it’s still a fringe process.

This method is more complicated, takes longer, and can’t be done in huge batches like the big coffee giants need. Rather than one step like with the spray drying method, there are three.

  1. The brewed coffee is frozen at subzero temperatures. Our Head of Coffee, Umeko, brews the freshly roasted coffee using a process specially designed for Sudden. The result is frozen below zero and the freeze-drying machine creates a vacuum to lower the pressure.
  1. A hint of heat is applied in the ‘primary drying phase’. Never going above zero degrees, a small amount of heat is applied to the frozen coffee in order for the water to sublimate. Essentially, the ice goes directly from a frozen to a gaseous state, skipping the liquid phase entirely and leaving behind mostly dry coffee crystals.
  1. Slightly more heat is applied. This ‘secondary drying phase’ uses a bit more heat to turn any remaining water molecules into gas. The coffee crystals that are left are now complete dehydrated—and all under zero degrees.

This process creates a higher quality instant coffee for a few reasons.

  • The lower temperature preserves aromas. Rather than being evaporated instantly from the crazy hot temperature, the aromatic compounds are allowed to remain inside the coffee crystals (and ready for your enjoyment).
  • The lower temperature maintains the chemical composition. Without the presence of heat, the acids are able to remain acids, the sugars are able to remain sugars, and the complexity of a delicious coffee is preserved.

A Brief History Of Instant Coffee

The idea of “instant coffee” is nothing new. Humans have been trying to make this stuff for hundreds of years! In fact, the first documented case of instant coffee being consumed is all the way back in 1771 . We’re talking before the United States had even revolted from Great Britain!

Speaking of Britain, that was where this first coffee was created, and we’re not talking about some quiet, out of the way invention. They called it “coffee compound” and there was even a patent issued for the new creation. It wasn’t until nearly a century later that the new wonder-product made its way back over to the colonies where it was experimented with during the American Civil War.

By the 20th century , several other countries got involved in the development, with Japanese inventor Satori Kato inventing the first stable powdered version, British chemist George Constant Washington helping commercialize it with his work in Guatemala, and the Brazilian coffee industry as a whole pushing it forward as a way to preserve their overflow coffee production.

Even Nestle got in on the action, creating instant coffee under the name “Nescafé” in 1938, which was incredibly popular with the military during WWII.

By the mid-century, the product had improved to the point where it had jumped to nearly a quarter of all consumed coffee, and ever since it has remained a popular hot beverage.

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