The coffee powder extraction process
Today, let us go through the coffee powder extraction methods.
Introduction to coffee:
One of the world’s most popular beverages is Coffee. The scientific name of Coffee is Coffea Arabica. Coffee is supposed to have been discovered by a goat herder. It’s the second most popular drink in the whole world.
Coffee is produced from the seeds of a small red fruit that grows on plants halfway in size between shrub & tree. The procedure that turns these seeds into a beverage is a long and complex process, perhaps the most complex process associated with any major beverage. Coffee has caffeine. Caffeine works by stimulating the central nervous system (CNS), heart, & muscles. There are two types of coffee. Arabica coffee was initially cultivated on the Arabian Peninsula. Robusta coffee is a hardy plant but contains double the amount of caffeine.
About the coffee plant:
Mature plant:
Coffee plants can grow to a height of 10 to 15 m at maturity but are kept at 3 min plantations for harvesting purposes. The shrubs remain productive for 15 years to 20 years. The elliptical leaves of the coffee tree are shiny, dark green, waxy and up to 1.5 to 2.4 cm long.
Leaves:
The leaves are simple, petiolate & have persistent stipules. Their underside is marked by small cavities. On the trunk & suckers, the opposite leaves are in crossed pairs, whereas on the branches they are on the same plane.
Flowers:
The white to pinkish color flowers are very fragrant and arranged in glom rules of 3 to 16, which, in turn, are grouped together in the axils of the leaves or above the leaf scars.
The tree flowers are ephemeral, withering a few hours after they have bloomed. Flowers occur in large bunches on old-growth wood, are normally self-fertile and will produce fruit without pollination.
The roots:
The roots of the coffee tree can extend 2.0m to 2.5m in total length. The tree taproots can penetrate to a depth of 2.5 to 4 min plantation situations.
The fruit:
The coffee fruit is oval, similar in size and shape to a small olive & turns red from green during ripening. The fruit is a fleshy berry, in which 2 seeds are embedded. Blossoming and fruit setting occurs mostly 2 to 3 times a year. About 6 to 7 months are necessary to ripen the fruit. The interim period between the flowering & ripening of the fruits varies, being determined by a number of factors (climate, latitude & altitude).
The extraction process of coffee:
Harvest maturity:
Coffee berries or fruit matures from May to October, depending on the climatic zone & the cultivars. Coffee berries are mature when they are red and soft. The coffee berries are complete 8 to 9 months after the plant flowers.
Harvesting methods for coffee extraction process:
There are four different ways of harvesting coffee, the first of the four types being the stripping method. This form of harvesting is done by hand, and it removes all of the berries, flowers, green berries & deeply over-ripened berries.
The second method of harvesting uses a comb to brush the trees. This method does remove all ripe berries, leaving the unripe berries as well as the green color leaves that are still connected to the branches of the tree. This is a time-consuming method, but it is worth the time invested. However, this process of harvesting must be more profitable because the unripe berries will eventually become ripe, increasing the future yield.
The third method used for harvesting is mechanical. A vibrator fixed to the trunk of the coffee tree is used to shake the ripe berries loose so that they fall to the ground where they can be reached with ease.
The fourth method is the most expensive because it requires hand picking the berries when they become ripe. The reason for this expense is that it must be done as many times as required until all the berries are picked. Picking must start from the center of the plant, using both hands. For the wet processing of coffee harvesting, the mature berries are picked selectively by hand either weekly or every second week. There are no machines that can pick the coffee berries selectively.
Read: Tea Powder Making Process.
Coffee powder extraction process:
Coffee berries & their seeds undergo several processes before they become the familiar roasted coffee. Coffee berries have been selectively picked by hand; a labor-intensive method, it involves the selection of only the berries at the peak of ripeness. More generally, crops are strip picked, where all berries are harvested simultaneously regardless of ripeness by person or machine. After picking, green coffee is processed by one of two methods the dry process method, as the berries can be strip picked, and the wet process method, which incorporates fermentation into the procedure & yields a mild coffee.
Then they are sorted by color, and most often the flesh of the berry is removed, generally by machine, and the seeds are fermented to remove the slimy coating of mucilage still present on the seed. When the fermentation is finished, the seeds are washed with a large amount of fresh water to remove the fermentation residue, which generates massive amounts of coffee wastewater. Lastly, the seeds are dried.
The best (but least used) process of drying coffee is using drying tables. In this method, the pulped & fermented coffee is spread thinly on raised beds, which allows the air to pass on all sides of the coffee, & then the coffee is mixed by hand. In this method, the drying that takes place is more uniform, & fermentation is less likely. Next, the coffee is sorted, & labeled as green coffee. Some companies use cylinders to pump in heated air to dry the coffee seeds, though this is normally in places where the humidity is very high.
Roasting in coffee powder extraction:
The next step in the procedure is the roasting of the green coffee. Coffee is generally sold in a roasted state, and with rare exceptions, all coffee is roasted before it is consumed. The roasting process influences the taste of the beverage by changing the coffee bean both physically & chemically. The bean decreases in weight as moisture are lost & increases in volume, causing it to become less dense. The density of the bean also influences the strength of the coffee & requirements for packaging.
The roasting begins when the temperature inside the bean reaches 200°C, though different varieties of seeds differ in moisture. During roasting, caramelization occurs as intense heat breaks down starches, which alters the color of the bean.
Sucrose is rapidly lost during the roasting process and can disappear entirely in darker roasts. During roasting, aromatic oils & acids weaken, changing the flavor; at 205°C, other oils start to develop. One of these oils is created at about 200°C, which is largely responsible for coffee’s aroma & flavor.
Roasting is the final step of processing the beans in their intact state. During this final treatment, while still in the bean state, more caffeine breaks down above 235°C. Dark roasting is the utmost step in bean processing removing the caffeine.
Raw materials required for coffee powder extraction:
Two of the 50 known species of coffee beans lead the beverage coffee industry. Coffee Arabica varieties, grown mainly in Latin America, India, and Indonesia, are relatively mild in flavor and, consequently, bring a higher price. They are relatively expensive to harvest since individual coffee cherries must be handpicked at their peak of ripeness. Coffee Robusta varieties, grown mostly in Africa, India, and Indonesia. It’s had a harsher flavor, but they are cheaper to grow since they can be harvested over a range of ripeness & are more resistant to diseases and insects. Because of their more attractive price, the robustas are generally used in the manufacture of instant coffees.
Roasting at temperatures above 300°F or 180°C drives the moisture out of coffee beans. Beans intended for use in instant products are roasted in the same method as beans destined for home brewing, although the moisture content may be left slightly higher (about 7-10%). The beans are then ground coarsely to minimize fine particles that could impede the flow of water during the industrial brewing system.
Direct Organic Solvent Extraction:
A common process of extracting caffeine from coffee beans is organic solvent extraction, using an organic solvent to wash the beans. First, steam the beans in a rotating drum for at least 30 minutes to open their pores, and then rinse them repeatedly for several hours with dichloromethane or ethyl acetate.
The caffeine saturates the solvent, so can remove it. At this stage, the caffeine extracted from the beans is now dissolved in the solvent, rather than the beans. After rinsing, you steam the beans for a second time, which evaporates the solvent, exit the caffeine behind as a white powder. The coffee beans are then vacuum dried. This method can extract caffeine from liquid coffee. Coffee is mostly water, so dichloromethane works since it is a water-immiscible solvent. When dichloromethane & water mix together, they separate into two layers.
Water Process Method of coffee powder extraction:
During the water process, you place the coffee beans in water and heat to around boiling points. This removes the caffeine from the beans, but it removes all flavors. You treat the mixture with a solvent, which absorbs & evaporates the caffeine. Finally, you put the beans in the mixture again to let them absorb the flavor they lost earlier in the procedure.
Supercritical Carbon Dioxide Extraction:
Another method to extract pure caffeine from coffee beans uses carbon dioxide. Carbon dioxide is a gas at atmospheric pressure and temperature, but if you raise the pressure & temperature, the gas changes into a supercritical liquid. In carbon dioxide extraction, rinse the beans with supercritical liquid carbon dioxide. Then, you filter the supercritical liquid to get rid of the extracted caffeine, & recycle it to use it again.
The dry process of coffee powder extraction:
The dry procedure enables us to obtain so-called natural coffee. There are totally four steps:
- Cleaning/sieving
- Drying
- Hulling
- Cleaning
If coffee harvesting has been carried out by means of stripping, it is all the more important to clean the beans from impurities & foreign bodies. The process usually involves sieving the cherries and then washing them with a strong jet of water; alternatively, the drupes can be immersed in tanks of running water. After washing, the dry method begins the cherries are dried in the sun, after being been placed on concrete patios.
Mixing at regular intervals allows all the cherries to be shown to the dehydrating effect of sunlight the fruits are left in the sun for between two & three weeks. In some areas, this procedure takes place by means of hot air in dryers for two or three days. Once maximum dehydration has been achieved, they are placed inside hulling machines that release the bean from the skin, pulp & parchment. At this step, the beans must be separated according to type & size, as they are not all of the same quality.
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The wet process of coffee powder extraction:
The wet procedure enables us to obtain so-called washed coffee.
In this stage, there are more steps:
- Cleaning/washing
- Maceration
- Pulping
- Fermentation
- Washing
- Drying
- Hulling
The wet process is used, particularly if the coffee cherries have been picked using the picking technique since the drupes need to be of consistent quality. It ensures higher quality results, first of all, the cherries are placed within tanks full of water to separate the ripe ones from the unripe or dry ones (cleaning phase).
The maceration stage, which takes place in special tanks, prepares the cherries for “pulping”. The cherries are placed in a device that extracts the seeds but still leaves some pulp on the seed. At this stage, fermentation takes place, which lasts from 24 to 36 hours & affects the taste of coffee. In this way, the seed and pulp are completely removed, followed by another washing stage to clean the beans more thoroughly. The penultimate phase involves drying by means of exposure to sunlight or by using particular drying machines. Finally, the parchment coating wrapped around the seed is removed by means of a hulling machine.
Dehydration:
Two basic methods are obtainable for converting the liquid coffee extract to a dry form. They are spraying drying and freeze drying. The spray drying method is done at a higher temperature, which affects the taste of the final product, but it is less costly than freeze drying.
Drying:
Drying can be done by either sun drying or mechanical hot air drying, & preferably on shade netting. By drying, 13 – 15% moisture content is reduced. Sun drying is cheap & makes a slightly higher-quality product but it requires much labor, space and time. The coffee must be laid 2.5cm thick & turned every hour.
Spray drying:
Cooled, clarified liquid concentrate is sprayed during a nozzle at the top of a drying tower. The drying tower is at least 75 ft tall. Air that has been heated to about 480°F is blown down during the mist to evaporate the water. The air is diverted out of the tower near the bottom, and it is filtered to remove fine particles, which can be recirculated back during the tower or reintroduced during the agglomeration step. The dry coffee powder collects at the bottom of the drying tower before being discharged for further processing. The resulting powder contains 2 to 4% moisture and consists of free-flowing, non-dusty particles. Spray drying may be followed by a step to form the powder into coarser particles that will dissolve completely in the consumer’s cup.
Freeze drying:
Freeze drying can be used instead of spray drying. The process involves totally four steps, beginning with “primary freezing.” Coffee extract is chilled to slushy stability at about 20°F. The prechilled slush is placed on a steel belt, trays, or drums & further cooled in a series of steps until it reaches a temperature of -40°F. Quick cooling processes taking result in smaller, lighter colored products, while slower processes taking generate larger, darker granules.
The slabs of ice are broken into pieces & ground into particles of the proper size of the drying step. The particles are sieved to ensure proper sizing, and those that are too small are melted & returned to the primary freezing stage. The frozen particles are sent into a drying chamber where, under proper conditions of heat & vacuum, the ice vaporizes and is removed.
Milling the Beans in coffee powder extraction process:
Hulling machinery can remove the parchment layer of wet-processed coffee. Hulling dry processed coffee refers to removing the whole dried husk the exocarp, mesocarp, and endocarp of the dried cherries.
Polishing is an optional procedure where any silver skin that remains on the beans after hulling is removed by machine. While polished beans are considered superior to unpolished ones, in reality, there is little variation between the two.
Grading and Sorting are done by size & weight, and beans are also reviewed for color flaws or other imperfections. Beans are sized by being passed during a series of screens. They are sorted pneumatically by using an air jet to separate heavy from light beans.
Normally, the bean size is represented on a scale of 10 to 20. Lastly, defective beans are removed either by hand or by machinery. Beans that are unsatisfactory due to deficiencies like unacceptable size or color, over-fermented beans, insect-damaged & unhulled are removed. In many countries, this process is done both by machine & by hand, ensuring that only the finest quality coffee beans are exported.
Cost of Coffee processing machine:
Coffee processing machine cost approximately – Rs 1.5 Lakh/Piece.
Equipment used for coffee production:
Different types of equipment used for coffee production. Some of these are;
- Pre-cleaner – Eliminates impurities for some agricultural granular products such as coffee beans.
- Rotary magnetic separator – Eliminates iron & steel mixed with grains, such as green coffee beans.
- Huller & polisher – Removes dried husks & parchment from green coffee bean
- Gravity separator – Separates coffee beans & other agricultural granular products by their specific weight
- Washing & Refining machine – Removes silver skins, polish the coffee beans
- Drum dryer
- Tower Dryer
- Coffee scaling equipment for roaster – This scale is auto-controlled for use in roasting & grinding coffee
- Coffee mixer – This mixer coffee is generally used for mixing coffee after roasting or grinding
Top coffee producing countries:
- Brazil
- Vietnam
- Columbia
- Indonesia
- India
- Ethiopia
- Mexico
- Peru
- Honduras
- Guatemala
The nutrition profile of coffee:
Many of the nutrients in coffee beans create their way into the finished brewed coffee.
A Single cup of coffee has:
Riboflavin or vitamin B2: 11% of the Reference Daily Intake (RDI).
Pantothenic acid (vitamin B5): 6% of the RDI.
Manganese & potassium: 3% of the RDI.
Magnesium & niacin (vitamin B3): 2% of the RDI.
Health benefits of coffee:
It’s a rich source of antioxidants: The environment is occupied full of free radicals (pollution particles, etc.) that wreak havoc on the skin. However, loading up skin with the antioxidants in coffee protects it & bolsters its natural defenses. In fact, coffee bean extracts can be responsible for skin cell energy preservation due to its free-radical properties.
Increase your fiber intake: A cup of brewed coffee represents a giving of up to 1.8 grams of the fiber of the recommended intake of 20 to 38 grams.
Coffee drinkers have stronger Deoxyribonucleic Acid (DNA): Coffee drinkers have DNA with stronger integrity because the white blood cells of coffee drinkers had far less instance of spontaneous DNA strand breakage.
Coffee reduces colorectal cancer risk: Even moderate consumption of coffee can reduce the odds of rising colorectal cancer by 26%. This protective advantage increases with more consumption.
Reduced heart attack mortality risk: Researchers found that those who drink 2 or more cups of coffee daily after having a heart attack have the least risk of dying from the heart attack.
Reduced liver cancer risk: Take 1 to 3 cups of coffee a day has a 29% reduced risk of developing liver cancer.
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