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

Photo by Robert Shunev on Unsplash

The Legend of the Coffee Goat

Legend has it that coffee was first discovered by Kaldi, a goat herder from Kaffa. One day Kaldi noticed one of his goats jumping around, almost dancing devilishly and bleating loudly. Upon further investigation, Kaldi found that the source of his possessed goat was from bright red cherries growing on a cluster of small shrubs. Deciding to test the cherries for himself, Kaldi noticed that the cherries had an instant energising effect!

I don’t know how far this legend is from the truth, however, I do know that if Kaldi or his curious goat were alive and well today, they would both probably be sipping on a french vanilla latte at Starbucks or sharing an instant coffee at home talking about the good old days.

I’m a man of simple needs and demands, so I would probably join Kaldi for that second option. Today we have moved passed those red cherries because nowadays we get our coffee on a shelf in the grocery store. However, if I was to be friends with Kaldi today, I’d first have to ask him if he likes his instant coffee spray-dried or freeze-dried?

What…you don’t know the difference? Oh my beans, please let me enlighten you.

Quick History Lesson: Who Was First?

Let me tell you something now. Researching the origin of instant coffee is bloody difficult. It seems that every second scientist or entrepreneur alive during the late 1800s has a claim to instant coffee in some shape or form. Yet, time and time again I kept coming across the following three most influential names:

1. Alphonse Allaise
2. David Strang
3. Satori Kato

Alphonse Allaise

The only information I could find on Alphonse Allaise was of a French humorist. However, I am not certain if this is the same Alphonse Allaise who basically invented “instant coffee”. Nonetheless, his claim to instant coffee was a french patent numbered 141,530 (image attached below).

Alphonse Allaise’s patent retrieved from Procaffeination.com

David Strang

Being a New Zealander myself, I was somewhat surprised to discover that David Strang was a pioneer in the instant coffee business. Strang is thought to have been the first person to commercialise instant coffee in Invercargill, New Zealand. His “soluble coffee powder” was patented in 1890 under the name Strang’s Coffee.

Satori Kato

Before Strang’s patent came to light, it was recently thought that the invention of the first commercial instant coffee was attributed to Tokyo chemist, Satori Kato. Mr Kato introduced his exquisite powdered coffee in Buffalo, New York, at the Pan-American Exposition in 1901.

Although it is unclear who was the godfather of instant coffee, we have a pretty clear indication of who it might have been (*cough*cough* Strang *cough*cough*). Regardless, let’s get stuck into the two main forms of instant coffee available today.

Extraction of Coffee Concentrate

The first step to producing instant coffee starts with the extraction of soluble solids and volatile compounds from roasted coffee beans. Volatile compounds may sound intense, but it really just means the aroma and flavour of coffee. This is done using water that is heated to 175˚C under pressurised conditions. The liquid slurry is then concentrated using evaporation or freeze concentration and further condensed into instant coffee using either spray-drying or freeze-drying techniques.

While spray drying is more economical for production, freeze-drying outperforms the former in terms of producing a higher quality powder.

Spray Drying and Freeze Drying

Spray Drying: 3-Step Rundown

1. Atomization — liquid sample is turned into tiny droplets using an atomizer.
2. Spray-air — the droplets are met with a steam of hot air (ranging from 80 up to 180˚C depending on the sample being dried).
3. Dry product — water particles are instantly evaporated, leaving behind fine solid powder.

Hey-presto! Your instant coffee has been formed.

Advantages

• Cheap to operate.
• Quick-drying process.

Disadvantage

• Long cleaning time.
• Raw materials are susceptible to degrading as high spray drying temperatures are used.

Freeze Drying: 3-Step Rundown

1. Freezing — sample is frozen below its triple point. The triple point is the lowest temperature at which the solid, liquid and gas phases of the material can coexist.
2. Primary Drying — the pressure is lowered in the freeze dryer. Heat is then applied, forcing ice crystals in the sample to sublime (turn from solid to gas).
3. Secondary Drying — removes any unfrozen water molecules.

Voilà! Your instant coffee has been formed.

Advantages

• Drying materials are less susceptible to physical and chemical alterations, or thermal degradation, as the raw materials are dried at low temperatures.
• Samples are easily reconstitutable (return to the state before drying).

Disadvantage

• Time-consuming process
• Expensive procedure

Photo by Kushal Permal on Unsplash

So Kaldi, Could We Ever Be Friends?

I don’t know about you, but I still check my labels before purchasing instant coffee. To be honest, sometimes I shake the bottle to see what the granules look like on the inside (cheeky me). My choice of coffee powder has to be freeze-dried. Even though freeze-dried coffee may be more expensive than spray dried. You can definitely taste the difference between the two. Freeze drying is energy-intensive and expensive due to the application of low temperatures and pressures. Spray drying, on the other hand, exhibits possibilities of losing certain aromatic compounds, due to high-temperature operation.

So to freeze-dried instant coffee, I say one thing…. words cannot expresso how much you bean to me….