Editing Instant coffee (section)

==Production==
[[File:Close-up of a granule of Gold Blend instant coffee.jpg|thumb|Close-up view of a granule of [[Nescafé]] instant coffee]]
As with regular coffee, the green coffee bean itself is first roasted to bring out flavour and aroma. Rotating cylinders containing the green beans and hot combustion gases are used in most roasting plants. When the bean temperature reaches {{convert|165|°C}} the roasting begins. It takes about 8–15 minutes to complete roasting. After cooling, the beans are then ground finely. Grinding reduces the beans to {{convert|0.5|to|1.1|mm|adj=on}} pieces. Until here, the process is in general the same as for other types of coffee.<ref name="MussattoMachado2011"/>

===Extraction===
To produce instant coffee, the soluble and volatile contents of the beans, which provide the coffee aroma and flavor, have to be extracted. This is done using water. Pressurized water heated to around {{convert|175|°C}} is used for this process. The coffee concentration in the liquid is then increased by either evaporation or by freeze concentration.<ref name="MussattoMachado2011">{{cite journal|last1=Mussatto|first1=Solange I.|last2=Machado|first2=Ercília M. S.|last3=Martins|first3=Silvia|last4=Teixeira|first4=José A.|title=Production, Composition, and Application of Coffee and Its Industrial Residues|journal=Food and Bioprocess Technology|volume=4|issue=5|year=2011|pages=661–672|issn=1935-5130|doi=10.1007/s11947-011-0565-z|hdl=1822/22361|s2cid=27800545|hdl-access=free}}</ref><ref>Archived at [https://ghostarchive.org/varchive/youtube/20211211/4G5LcVUcWAg Ghostarchive]{{cbignore}} and the [https://web.archive.org/web/20180311144244/https://www.youtube.com/watch?v=4G5LcVUcWAg Wayback Machine]{{cbignore}}: {{cite AV media |title=How It Works - Instant Coffee |medium=video |language=en |url=https://www.youtube.com/watch?v=4G5LcVUcWAg |access-date=4 March 2016 }}{{cbignore}}</ref>

===Freeze drying===
{{No footnotes|section|date=March 2016}}
[[Image:Production freeze dryer.JPG|thumb|right|A [[freeze drying|freeze dryer]]]]

The basic principle of [[freeze drying]] is the removal of water by [[sublimation (chemistry)|sublimation]].

Since the mass production of instant coffee began in post-WWII America, freeze-drying has grown in popularity to become a common method. Although it is more expensive, it generally results in a higher-quality product.

# The coffee extract is rapidly frozen and is broken into small granules. (Slower freezing would lead to larger ice crystals and a porous product; it can also affect the colour of the coffee granules).
# The granules are sifted and sorted on size.<ref name="MussattoMachado2011"/>
# Frozen coffee granules are placed in the drying chamber, often on metal trays.
# A vacuum is created within the chamber. The strength of the vacuum is critical in the speed of the drying and therefore the quality of the product. Care must be taken to produce a vacuum of suitable strength.
# The drying chamber is warmed, most commonly by [[thermal radiation|radiation]], but [[heat conduction|conduction]] is used in some plants and [[convection]] has been proposed in some small pilot plants. A possible problem with convection is uneven drying rates within the chamber, which would give an inferior product.
# Sublimation—the previously frozen water in the coffee granules expands to ten times its previous volume. The removal of this water vapor from the chamber is vitally important, making the condenser the most critical and expensive component in a freeze-drying plant.
# The freeze-dried granules are removed from the chamber and packaged.

===Spray drying===
{{main|Spray drying}}
[[Image:Labspraydryer.svg|thumb|Laboratory-scale spray dryer.<br /> A=Solution or suspension to be dried in, B=Atomization gas in, 1= Drying gas in, 2=Heating of drying gas, 3=Spraying of solution or suspension, 4=Drying chamber, 5=Part between drying chamber and cyclone, 6=Cyclone, 7=Drying gas is taken away, 8=Collection vessel of product, arrows mean that this is co-current lab-spraydryer]]

Spray drying is preferred to freeze-drying in some cases because it allows larger scale economic production, shorter drying times, and because it produces fine rounded particles.

The process produces spherical particles about {{convert|300|μm}} in size with a density of 0.22&nbsp;g/cm<sup>3</sup>.<ref>{{cite book | title = Spray Drying Handbook | edition = 5th | first = K | last = Masters | year = 1991 | publisher = Longman Scientific & Technical | isbn = 978-0-582-06266-5 }}</ref> To achieve this, nozzle atomization is used. Various ways of nozzle atomization can be used each having its own advantages and disadvantages. High speed rotating wheels operating at speeds of about 20,000&nbsp;rpm are able to process up to {{convert|6000|lb|kg}} of solution per hour.<ref>{{cite book | title = Encyclopedia of Chemical Processing and Design | editor = John J. McKetta | publisher = Marcel Dekker Inc | year = 1995 | isbn = 978-0-8247-2604-1 }}</ref> The use of [[spray wheel]]s requires that the drying towers have a wide radius to avoid the atomized droplets collecting onto the drying chamber walls.
* Completed in 5–30 seconds (dependent on factors such as heat, size of particle, and diameter of chamber).
* Moisture content change: IN = 75–85% OUT = 3–3.5%
* Air temperature: IN = {{convert|270|°C}} OUT = {{convert|110|°C}}

One drawback with spray drying is that the particles it produces are too fine to be used effectively by the consumer; they must first be either steam-fused in towers similar to spray dryers or by belt agglomeration to produce particles of suitable size.

===Decaffeination===
{{See also|Decaffeination}}
In commercial processes, the decaffeination of instant coffee almost always happens before the critical roasting process which will determine the coffee's flavour and aroma processes.

===Byproducts===
The main byproduct of the instant coffee production process is spent coffee grounds. These grounds can be used as biomass, for example to produce heat used in the manufacturing process.<ref>{{cite web|url=http://www.madehow.com/Volume-3/Instant-Coffee.html|publisher=Madehow|title=Instant Coffee}}</ref> Roughly two times the mass in spent coffee grounds is generated for each quantity of soluble coffee.<ref>Pfluger, R. A. (1975). Soluble coffee processing. In C. L. Mantell
(Ed.), Solid wastes: origin, collection, processing, and disposal.
New York: Wiley.</ref>