Three Techniques For Making Instant Coffee, What Are The Differences?
There are three techniques for making instant coffee, spray drying, secondary granulation, and freeze drying. What are the differences then?
Spray drying technique and freeze drying technique
Both spray drying and freeze drying are methods of drying and dehydrating. The two techniques compress and extract the coffee, keep the coffee taste unchanged, and make it show specific water-soluble properties.
The spray drying technique is a high-temperature extraction process in which the extract is sprayed through a hot air jet and the water contented is quickly evaporated, leaving dry coffee grains.
This high-temperature extraction process can realize a large amount of rapid production, and the cost is lower than that of a freeze drying technique.
But the bad thing is that while the instantaneous high temperature vaporizes the moisture, it also damages many aromatic substances, which causes the flavor of instant coffee produced in this mode to be greatly reduced.
Sometimes it will cause coffee “allergic reaction”. When changing the physical form, high temperatures will also change the chemical form of coffee, and some of the original nutrients will also be lost.
However, the freeze drying technique somehow overcomes the shortcomings of spray drying and is the main extraction method for sublimation.
The specific extraction method using freeze drying technique is to freeze the water-containing items below 0 degrees, thus condensing the water into ice, and then turn the ice into steam under vacuum to complete dehydration and drying.
Since freezing and sublimation requires a certain process and the pressure must be strictly controlled, it is not easy to mass-produce and the production cost is high, which is 5 times that of ordinary instant coffee.
However, compared to the high-temperature spray drying technique, the application of freeze drying tech in coffee is an advancement to maximize the preservation of coffee flavor.
In addition, in the low-temperature state, the protein and many coffee nutrients will not be lost or changed, making the coffee grains plump, while having the original mellow aroma and smooth taste of the coffee.
Granulation and freeze drying technique
In 1905, the granulation technology was applied to skimmed milk powder. Coffee made of this process is easier to confuse with freeze-dried coffee, but you will find that the freeze-dried coffee particles are distinct, while the second-granulated coffee has a powdery texture.
There are many methods of granulation, which can be summarized as the following 6:
1.Rotary granulation — by rotating/vibrating to mix up moist powders and then coagulated them.
2.Fluidized bed spray granulation — particles in fluidized bed drip and agglomerate.
3. Squeezing granulation — squeezing particles in the mold to make them agglomerated.
4. Compression granulation — compressing powder into a mold.
5.Crushing granulation —make the powder agglomerate and then redisperse
6.Jet granulation —cooling and solidification of molten material
However, the secondary granulation will only cause a morphological change, and the basic flavor extraction process has not been improved. Therefore, when drinking, many people often have a scorched taste at the beginning and need time to adapt it. This situation will not occur in coffee made by freeze drying or spray drying technique.
Come to Hawach to choose your ideal lyophilization machine and spray drying machine.