It is not a surprise that coffee is the most popular drink in the world. This beverage made from roasted coffee beans gives us an instant energy boost to power us through the day. According to British Coffee Association, we consume around 2 billion cups of coffee each day. But in today’s fast pace world that we live in, there is no wonder that most of us would opt for an instant coffee. This article from Washington Post says that almost half of the world prefers instant coffee instead of a cup of freshly brewed coffee. Sure, instant coffee is a quick caffeine fix to finish a busy day at the office. But are we losing some things with instant coffee that we would get from brewed coffee? A quick review of how instant coffee is made will better answer this question.
Spoiler alert: instant cofee is made from real coffee!
Let’s dive right in.
Table of Contents
COFFEE CHERRIES TO GREEN COFFEE BEANS
Harvesting
It may sound simple, but the process of making coffee beans is labor-extensive, actually. This especially true when the coffee cherries are picked or harvested selectively. This way, the cherries are hand picked individually to carefully choose only those that are at their peak ripeness. Cherries of equal maturity ensures better quality of coffee. This is the reason why most coffee farmers use this method.
The less common way of harvesting cherries is by strip picking. In this method, the cherries are harvested or “stripped” off the branch simultaneously regardless of the stage of maturation. Strip picking can be done by a person or a machine.
Processing
After harvesting, processing follows to separate the bean from the cherry. This can be done in two main ways: dry method and wet method. Dry method is the oldest and simplest method of processing. This way, the cherries are spread out on a concrete or drying beds to sun dry. If an even pavement is not available, farmers use nets made of mesh wire. To ensure even drying and prevent spoilage, the cherries are turned every so often.
In some cases, sun drying is combined with and followed by mechanical drying to speed up the processing. Drying takes several weeks to complete (about 4 weeks). By the end of the process, the moisture content should be around 9-12%.
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In the wet method, a depulping machine removes the pulp of the cherries. What is left here are beans, Â the mucilage (slippery outer skin) and a parchment skin. The beans are then cleaned and sorted out by weight. After that, the beans are placed in large fermentation tanks for 14 to 72 hours. By doing so, the naturally-occurring enzymes break down and remove the mucilage. Then, washing follows to remove fermentation residues. After fermentation, the beans should have a moisture content of around 56%. This is brought down to 9-12% by drying for up to 10 days.
As we can see, the wet method is a faster method of processing coffee cherries than the dry method. Furthermore, it helps produce better quality coffee. In fact, this Nepalese comparative analysis study found out that the wet method produced coffee of purer flavor and more pronounced aroma.
Milling of coffee beans
At this point, there are still layers that surround the beans. The milling process removes them. This a two-steps steps— hulling and polishing.
Hulling is an optional step during milling. And what it removes depends on how the beans have been processed. If the beans have been processed by dry method, It removes the dried husk entirely, which include the exocarp (skin), mesocarp (musilage) and the endocarp (parchment).
Hulling of coffee beans that have been wet-processed, on the other hand, only removes the parchment.
After hulling, polishing further removes the silver skin that has not been removed during hulilng. Some millers skip this step, but it is believed that polished beans are of better quality than unpolished ones.
Then, quality checking by hand and/or machine. Here, the beans are checked and sorted out depending on the parameters being checked. Commonly, the beans are sorted depending on the color, size, and weight. One way of checking the size and weight is blowing air using an air jet to separate the heavy coffee beans from the light ones. Coffee beans are also removed for any defects such as insect infestation, over-fermentation, mold growth, and cut or broken beans. This ensures only the finest coffee beans are packed.
Milled beans, commonly referred to as green coffee beans, that have passed the quality requirements are now ready for shipment to the coffee factory.
GREEN COFFEE BEANS TO INSTANT COFFEE
Here comes the interesting part.
These coffee beans are delivered to the factory via lorry. Every production day, tons of coffee beans are delivered to satisfy the demand for instant coffee. Prior to roasting, the beans are first sieved to ensure that debris and other foreign materials are totally removed.
Roasting
Then comes the roasting part. This is done by heating the beans in a large commercial roaster. Stirring prevents burning and ensures uniform roasting of the beans. The introduction of heat allows for chemical reactions to occur. One example is the formation of melanoidins, large molecules that are responsible for browning (Maillard reaction) of coffee beans. Along with browning is the thousands of volatile and non-volatile compounds that in general are responsible for the aroma and flavor profile of coffee. One particular volatile compound is 4-(4-hydroxyphenyl)-2-butanone, one that gives its fruity and sweet aroma.
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Roasting typically lasts for 10 minutes before immediate cooling to minimize the impact of residual heat. And this is carefully monitored. Any change, however little, in the length of exposure to heat and temperature may impact the aroma and flavor.
Grinding
Grinding uses a high-powered industrial roller mill grinder, which turns the beans into coarse powder. This kind of machine can grind over 1000 kilograms of coffee beans per hour. The bad thing about grinding is that takes away the freshness in the beans. Once the beans have been ground, aroma-producing compounds start to escape. The longer the beans are left exposed to air, the staler they become. Studies have shown that coffee beans tend to lose up to 60% of their aroma after 15 minutes. This is the reason why coffee packaging is flushed with nitrogen gas to displace oxygen. Doing so makes the coffee as fresh as the day it was packed while retaining the aroma.
To reduce the losses after grinding, nitrogen gas is pumped to collect the aromas (vapor), which are later added back.
Brewing
This part is what most is familiar about— brewing. This helps recover the flavor and aroma of the coffee. While most us do this part as well at home, adding hot water onto ground coffee beans to brew in the factory is different. There, brewing deals with over 600 kilograms of coffee that goes through a huge extraction pod.
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Evaporation
After brewing, the coffee is sent to an evaporation tank. This tank is huge that it can hold roughly a million cups of coffee. Through the evaporator, the coffee is warmed, evaporating and removing the water. Then, the coffee is heated until it condenses to an extract. Evaporation helps increase the coffee concentration. This extract is moved via conveyor to the next step, freezing.
Freezing
This is done in a large freezer. While working, workers require a thermal jacket in order to protect themselves from the extremely low temperature. The inside of the freezer maintains a temperature between -40°C and -50°C. This low temperature facilitates rapid freezing of coffee. Freezing the coffee extract helps preserve the aromas.
While frozen, the coffee is broken into granules using a granulator. At this point, the challenge is to remove the remaining water in the coffee. To achieve this, a process called sublimation is performed.
Sublimation
Sublimation is a process in which a substance in the solid state is converted into gaseous state, without first becoming liquid. If the coffee became liquid, the aromas that are locked in would be lost. To prevent this, the granules are placed in trays of a freeze-drier and heated at 60°C (140°F) in a vacuum. While under pressure, the remaining frozen water vaporizes directly into steam. A properly freeze-dried coffee granules have their aromas preserved. And they would remain solid at room temperature. For more details on freeze drying, see this post: The Process Of Freeze Drying.
What is next is adding back the aromas that have been saved during the grinding process. To do this, the aromas are sprayed over the coffee granules before packing them in sacks.
The coffee is now ready for packaging in individual glass jars that are lined up on a conveyor. Instant coffee is hygroscopic, it can absorb moisture from the air. To maintain the freshness of the coffee, a lid with an airtight seal is used to prevent oxidation.
Spray-drying (Alternative to freeze-drying)
Spray-drying is the other way of producing instant coffee. In this method, the liquid coffee is sprayed through a nozzle at 400mph into a hot, dry atmosphere chamber (200 and 300 °C). This high-speed air that moves downward instantly atomizes the liquid coffee, eliminating the water, and producing coffee in powder form that settles at the bottom. Then, the aromas that have been captured and saved in the earlier process are sprayed over the coffee.
Compared to freeze-drying, spray-drying has several advantages. First, drying the coffee takes little time. Second, it allows for rapid evaporation. And lastly, it can handle large volume and continuous production.
But despite these, freeze-drying is still the go-to method of producing coffee. The main reason for this is the excessive lost of aroma as a result of rapid evaporation during spray-drying, resulting in a lower quality coffee. A coffee lover who enjoys instant coffee both in granular and powder form will definitely tell the difference.
WHAT IS LOST DURING INSTANT COFFEE MANUFACTURING?
Aroma and flavor
Manufacturing of instant coffee is a stressful process. This is especially true during grinding, where volatile aroma compounds are released and lost to air. This oxidation starts as soon as grinding is started. This is the reason why it is recommended to brew ground coffee immediately. As already mentioned, 60% of the aroma of coffee is lost after 15 minutes. It is true that these aromas can be captured, saved, and added back at a later stage of manufacturing. But when it comes to retaining oils and aromas, a cup of fresh brewed coffee still beats most instant coffees.
Caffeine
Coffee is made up of over a thousand of chemicals. Of these chemicals, caffeine will always be more synonymous with coffee. In fact, we source this naturally-occurring stimulant from coffee. If consumed in moderation (50–300 mg), caffeine improves memory function, reduces fatigue, and enhances performance. A study found out that shift workers who consume coffee make less error at work.
But truth be told, instant coffee contains the least amount of caffeine. The National Nutrient Database for Standard Reference says a 8oz (227ml) cup of instant coffee has 62 mg of caffeine. But a regular or freshly brewed coffee of the same amount will give you 95 mg of caffeine. These numbers still vary though. Instant coffee can contain up to 90 mg caffeine, whereas a regular coffee can contain up to 140 mg of caffeine. This depends on the manufacturing process (particularly roasting and brewing), and the stage of maturity and the type of coffee beans. Like for example, Robusta beans, which most instant coffees are made from, contain more caffeine (2.7%), whereas Arabica beans have 1.5% caffeine.
Obviously, instant coffee will benefit those who wish to lower their caffeine intake. Decaffeinated coffee is an instant coffee whose caffeine content has been reduced. This coffee has a milder taste. And hence for people who do not prefer the strong bitter taste of regular coffee. In the US, in order to carry the decaffeinated label, 97% of caffeine must be removed.
