Harvest, processing and storage of coffee beans

Processing and harvesting of coffee beans

The annual winter, that is, the dry season is the harvest time for coffee beans. After three to four years of growth, the coffee trees gradually mature and begin to bear fruit. The fruits are arranged in strings or clumps next to the branches. The coffee beans are wrapped in a red coat and can be picked as soon as they turn red.

Most Arabica coffee beans mature from June to August and Robasta coffee beans from September to October, so although in some countries where the dry and wet seasons are not obvious, such as Colombia and Kenya, there are two flowering periods a year, that is, two harvests, but technically only once a year.

Of course, the harvest date varies from region to region. To the south of the equator, such as Brazil and Zimbabwe, the main harvest is in April or May, although it can last until August, while regions north of the equator such as Ethiopia and Central America are generally harvested in September-November. However, equatorial countries, such as Uganda and Colombia, can harvest all year round, especially those plantations that make good use of different elevations. As a result, newly harvested coffee beans are available for most of the year.

As far as picking coffee beans is concerned, there are two ways. One is picking in pieces, that is, picking all the beans in the garden at once, and the other is picking selectively, that is, picking only the ripe red berries at intervals of 8 to 10 days, so you need to pick more times in the garden. Compared with the former method, the latter method is labor-intensive and expensive, and is generally used only for Arabica coffee beans, especially those that need to be washed.

The number of coffee beans picked depends on a variety of factors, the most obvious being the height of the trees and the layout of the farm or plantation. The average farm can pick an average of 50 to 100 kilograms a day. But only 20 percent of these beans are real coffee beans, so the average picker can only pick 10 to 20 kilograms of coffee beans a day. Coffee beans are in bags with a standard mass of 45 to 60 kilograms. As a result, it takes some workers three to six days to fill a bag.

It has been calculated that the cost of harvesting a plantation or farm is half of the total cost of the year. In Brazil, people have tried many times to reduce these costs by mechanical picking. The machine shakes the branches across the coffee tree so that the berries that become loose because they are ripe will fall into the funnel. But this can only be done in places with better natural conditions, and they need to be adjusted first, because the machine can only be used where the trees can be planted in straight rows. Afterwards, you also need to check the mechanically picked coffee beans and practice the leaves and branches that fell in the funnel. Picking in this way is still troublesome.

In areas with relatively high elevations, such mechanical picking method cannot be adopted, and manual picking must be used, which requires a large number of seasonal workers. Pickers should also be careful not to pick coffee beans that are not ripe, bad or too ripe, as they will affect the overall quality of the coffee harvested.

The original picking method ensures the quality of coffee bean picking to a great extent. Those coffee beans that are not so good are classified as ordinary acid fermented beans, and the last one is very bad.

Rough processing of coffee beans

A coffee bean is a seed that resembles a cherry fruit, and its skin appears red when it is ripe. Each fruit is wrapped in a parchment-like skin, and under the flesh, in the middle, lies two coffee beans with flat sides leaning against each other.

When the fruit is ripe, the parchment is wrapped in a thin, thin layer of glue. The beans under the parchment are covered with another thinner film, which is a silver pericarp, or seed coat. Each cherry fruit usually contains two coffee beans; if there is only one, it must have a more round shape, which is called pea-shaped coffee beans.

Coffee beans must be removed from the fruit and dried before roasting. This process can be completed in two days and can be dried or wet. When this process is completed, the coffee beans to be roasted are called raw coffee beans. Coffee beans are the seeds of coffee cherries. Every winter, that is, the dry season is the harvest time, and there are many harvesting methods. The bean itself is wrapped in many layers of material, including a silver skin, parchment-like paper, slime, slime, and its watch case. The interaction between these sweet, sticky substances and the coffee bean itself determines the taste of many coffee beans; similarly, the method used when the coffee bean is removed from the cherry can also affect its taste.

There are basically three ways to take out coffee beans, wet, dry, and semi-dry and semi-wet.

The coffee bean itself is wrapped in many layers of material, and every coffee bean has a thin outer membrane, which is called silver skin, and its outer layer is covered with a yellow skin, called pulp, while the whole coffee bean is wrapped in a sticky prize to form coffee pulp, and the outermost layer is the shell.

The process of processing coffee seeds into commercially valuable coffee beans is called refining. Drying method is used for unwashed coffee beans, and wet treatment is used for thoroughly washed or semi-washed coffee beans.

Except for the more common use of drying in Brazil and Ethiopia, most Arabica coffee beans are processed by wet treatment. At one time in Nicaea, some robastian coffee beans were processed by wet treatment, but this is not common in the region.

1 drying method

Drying, also known as natural drying, non-washing, is the cheapest, simplest and most traditional method of processing coffee beans, which requires drying the whole coffee fruit. There are also many differences in the implementation of this process, depending on the size of the farm plantation, the equipment available and the final quality required. The basic three steps are cleaning, drying and peeling, which are described in detail below.

First of all, the harvested coffee fruits are usually sorted and washed, picking out the immature, overripe and damaged ones, and removing dust, soil, twigs and leaves. This is usually done by hand, using a large sieve in which any coffee fruit and other beans needed can be left at the top of the sieve and picked out. Ripe coffee fruit can also be separated by flotation in the sink, which is close to the stage of drying.

Spread the coffee fruit in the sun, usually using large concrete floors, brick platforms, or straw mats lifted to the middle of the fork. As the coffee fruit dries, apply a hand rake or turn it over to make sure it is drier.

It takes four weeks for the coffee fruit to dry to the best 12.5% humidity, depending on the weather. On larger farms or plantations, a dryer is sometimes used to speed up the process after the coffee fruit is exposed to the sun for a few days in advance.

At this time, the surface of the coffee fruit becomes dark brown and fragile, and the coffee beans can be heard cackling in the shell. In Brazil, coffee beans at this stage are given the name cocoa that agrees to be confused.

The drying process is the most important stage in the whole process, as it will affect the final quality of coffee beans. Overdried coffee beans can become brittle and lead to many broken beans when peeled. Chopped beans are considered bad beans, while coffee beans that are not completely dry are too wet and can deteriorate easily once bacteria invade.

Dried coffee fruits will be stored in special soil piles until they are transported to the mill. Peeling, sorting. Grading and packing, these processes will be carried out there. The outer skin of all dried coffee fruits will be removed in the steps performed by the peeling machine.

Ninety-five percent of Arabica coffee produced in Brazil is dried, and the vast majority of coffee in Ethiopia, Haiti and Paraguay is also produced in this way. Almost all robastian coffee is produced in this way. This method does not apply in areas where the air is humid or where the harvest season is rainy.

2Wet treatment method

After the coffee is picked, it needs to be peeled, fermented, cleaned, dried, threshed, screened and so on. In this program, water can be used, which is called wet treatment. Wet treatment is also called water washing, wet method, which requires much more money and energy not to dry, but it is also easy to cause environmental pollution, but this method can better ensure the quality of coffee beans and reduce losses.

Separate

During wet treatment, the pulp is immediately separated from the coffee instead of drying it. The separation of pulp is carried out by using a separator. The fruit of bacca is placed in a machine with a fixed surface and a movable surface, or in a machine with a movable rod, the fruit is mechanically crushed to separate the pulp from the coffee beans.

The pulp must be separated after harvest, which is ideal within 12 hours and no more than 24 hours at the latest, in order to ensure the quality of coffee beans. If the coffee beans are kept for too long, the pulp will become difficult to separate from the coffee beans, resulting in incomplete separation and possible damage to the coffee beans.

classification

Also, the separated peel and pulp of coffee beans will be washed with water. The flushing tank is designed to separate light and tender coffee beans from thick and ripe coffee beans. Put the fruit in the sink for about 24 hours. From which we will see that the ripe fruit will sink, while the immature fruit will float on the surface, using this method to select.

Some of the coffee beans picked are freshly ripe, overripe, and immature, all mixed together. If these coffee beans are not treated separately, the quality of the coffee beans is really unpalatable, because it is mixed with a lot of bad-tasting impurities. So these coffee beans have to be washed and placed in a spring tide filled with water for preliminary classification.

Good coffee is relatively dense, so it will sink into the water. On the other hand, overripe coffee beans will surface and can be easily classified.

Unfortunately, those coffee beans that are not yet ripe will sink to the bottom of the water and mix with those that are ripe. So use wet treatment for those immature coffee beans, or use drying treatment to classify them after a while.

Such a separation can also be done by an Austrian high score machine. Ogao, a Norwegian coffee grower, designed a device to filter coffee beans into a large water container through a filter while growing coffee in Kenya. The large, full beans first sink into the water. The lighter beans stay in the large container all the time. In this process, water can be recycled.

Ferment

Then there is the most basic fermentation, that is, using the action of enzymes to separate the greasy glue that covers the peel of the flesh. The coffee beans are stored in the fermentor for about 12 to 36 hours, depending on the surrounding temperature, the thickness of the glue and the enzyme. When the fermentation is finished, the peel around the coffee bean feels like a pebble and is no longer sticky.

Because its process is more complex, it is sometimes easier to leave the flavor during fermentation, or because of the different treatment of the drying process, it leads to abnormal odor and the taste becomes worse. And the quality changes in preservation should also be paid full attention to.

Drying

After wet treatment, the coffee beans are preserved in the pulp shell, which still contains about 15% water. The flesh fruit must be dried to a moisture content of about 11% to ensure that coffee beans are stored in a stable and safe environment.

Water content is very critical, neither too much nor too little. If Arabica coffee beans are overdried to 10% perspiration, they will lose their original turquoise and their quality will decline.

The drying process can also be done by the sun, and coffee beans should be turned over regularly to ensure complete dryness, a process that takes 12 to 15 days. The most important thing is that the endocarp should not be cracked. If the sun is too strong, the coffee beans must be covered.

At this point, the whole process is completed, coffee beans have completed the well-known 'parchment coffee beans', because the endocarp of coffee beans is quite like parchment, so it is said. In general, coffee beans are kept in this form until they are exported.

In the process of over-wet treatment, preventing coffee bean rot is a crucial point in quality control, and the equipment used must be cleaned every day to ensure that no impurities are left before the next round of processing. Because even if only one coffee bean is rotten, the beans may damage all the coffee beans.

(3) semi-wet treatment

Semi-wet treatment, also known as natural removal of pulp, is a relatively new method. This method can only be used in specific areas of some countries, such as a long drying period in the climate, before it can be used to deal with local coffee.

The coffee harvest produced by this method is sticky, and the mucus is not removed with fermentation in the tank. Therefore, the coffee produced by this semi-wet treatment contains the characteristics of both wet treatment and drying treatment. The acidity, sweetness, seasoning and flavor of this coffee are quite good, the only disadvantage is that the taste of this coffee is not as strong as that produced by pure drying or wet treatment.

Shelling

Coffee beans should be ground before they are exported, that is, the endocarp of Arabian and Robbite coffee beans to be sold should be removed. The residual shell of coffee beans after removal and cleaning of endocarp and drying process is also known as peeling or peeling.

It is more difficult to remove the endocarp of coffee beans during wet treatment than during drying, so different shelling machines are needed. There are mainly two types of machines: friction sheller and compaction sheller. The Engelberg and African models of friction shellers are suitable for dry or wet coffee beans: in an one-person cylindrical box, the coffee beans are squeezed between a linear strip and a knife, and the shell is scratched by a knife to reveal the beans.

Parchment coffee beans are usually shelled on a Smout friction sheller. The machine is equipped with a rotating body with a screw, which rotates in a box with a screw, which rotates in the opposite direction. When the coffee bean is driven along the rotation, the endocarp is peeled off the coffee bean. Because the rotating body rotates relatively slowly, it produces less heat than other types of shelling machines.

Other shellers include rolling shellers (mainly used for dried coffee beans produced in South America) and crossbar shellers (with knives inside).

In other places except Brazil, the parchment coffee beans are treated with a pressing sheller instead of rubbing the sheller. Coffee beans must have moderate water content when shelling, or they may break. The pressing sheller consists of a horizontal disk rotating in a ring, and the edge of the plate is surrounded by an iron needle or rod. When the machine is running, the coffee bean comes into contact with the iron needle due to the action of centrifugal force, which makes the endocarp shell fall off.

It is worth noting that coffee beans must have moderate water content when shelled, or they may break.

Polishing

The silver skin left on the coffee beans after shelling must be removed by polishing. Most polishers work in a similar way to Smoot shellers, except that copper rods are used instead of iron rods, which cause less damage to coffee beans. Copper also plated coffee beans with bluish blue. Coffee beans treated with a pressure sheller are usually polished because they always look more messy than those shelled by friction.

Some people once thought that polished coffee beans were of higher grade than unpolished ones. In fact, when the final drink is tasted in a cup, it makes almost no difference. There are also people who stubbornly believe that the value of polishing will be affected by the quality of the cup, but it is difficult to find hard evidence.

Grading

Coffee beans are graded in different countries according to different grading systems. Coffee beans are graded first by size and then by density. With two exceptions, all coffee beans have a considerable size and the same proportion, with flat on one side and semi-oval on the other. The special cases are pea-shaped coffee beans that tend to be more oval in shape and giant coffee beans with large particles (that is, Marragol peel coffee beans).

Generally speaking, large coffee beans can produce better coffee. Coffee beans are usually graded on a scale of 10 to 20, but in some countries coffee beans are graded according to levels corresponding to a certain size, such as AA. The way to determine the size of coffee beans is to pass them through a sieve. But even so, there may be weight differences between coffee beans of the same size, and bad, crumpled coffee beans that have to be removed will still remain.

classification

The best way to separate unwanted coffee beans from good ones is to use gravity and air. The compressed air method is operated manually and requires higher technology. it uses jets to separate heavy and light coffee beans. Another method, the weight separation separator, is to put the coffee beans on a raised plate and let the air pass through them to make the heavy coffee beans fall. This is also a technologically demanding method, if used properly, the coffee beans can be separated more accurately and effectively.

The next step is to sort these coffee beans. Remove rotten, black, sour and overfermented or unshelled coffee beans. This process depends on eyesight, putting the beans on a moving belt to check. Other methods include the electron color classification (mainly used for Robbaut coffee beans) and the dichromate (bichromatic) method, which uses light detection to find bad beans. Today, however, the best test classifier is still the human eye. But high-tech microprocessing systems will eventually replace this process completely.

Storage

Since countries that produce coffee beans need to export coffee beans throughout the year, rather than just about three months of harvest, coffee beans should be preserved in the form of 'parchment coffee beans' in a relatively stable environment.

High temperature is the enemy of coffee beans, and it is easy to damage coffee beans when the humidity reaches 70%. For this reason, parchment coffee beans are generally not kept on farms where they are produced.

Coffee beans grown in the highlands should be kept at the same altitude as or close to the altitude where they are grown, as they are particularly vulnerable to humidity. In this environment, Arabica coffee beans should not be stored for more than 12 hours, while Robart coffee beans can be stored for a longer period of time.

There are many preservation methods, but the most effective, simple and direct method is one-way valve packaging such as automobile tire basketball safety valve, and sealed barrel packaging, the packaging material is moisture-proof, gas-proof and light-proof. The gas can only come in and not go out, but ask the guest and businessman about the aroma. In a strict sense, the packaging of coffee is not vacuum packaging, the packaging contains nitrogen to maintain the original flavor of coffee beans. Processed beans will release secondary carbon in the process of storage, one-way valve packaging can effectively discharge the carbon dioxide out of the bag, but the sealed bucket can not.

Storage of coffee

1. I hate water most. Two natural enemies of coffee; water and oxygen. Coffee beans should be kept fresh in sealed bags, sealed with leftovers and used up within 15 days after opening the package.

two。 Put it in a cool and ventilated storeroom.

3. The shelf life of coffee beans is about 3 months, while coffee powder is only 7 to 15 days. The more detailed the coffee powder, the shorter the storage time, even only 3 days.

4. Ground coffee is sealed or vacuum packed to ensure that the coffee oil does not dissipate, resulting in a loss of flavor and strength, if not quickly used, can be placed in the refrigerator.

5. Recycle inventory and check the grinding date on the bag.

6. Store caffeine away from food that has a strong irritating taste.

7. The coffee has four flavors and one fragrance, sour. Sweet。 Bitter. Astringent and condensed fragrance. Grind it as much as possible when needed. Boil it now. Brew. This is the freshest and best coffee. Otherwise, like pepper, it loses its fragrance soon after grinding.

Transport

After shelling, the coffee beans, in units of 60 kilograms, are packed in a coarse sack and ready for export.

In the world coffee trade products of raw coffee beans, fried coffee beans, ground coffee, instant coffee, mainly raw coffee beans, coffee beans every year there are 500-6 million tons to be exported, they start from the plantation, are carried out on animals, then by land, water, railway, until today's aviation system to reach all parts of the world, have experienced a long process of transportation.

Coffee is stored and transported in the form of parchment coffee beans before being exported or sold. Although this has added the weight of coffee and increased the transportation cost of coffee, it plays a certain role in protecting the quality of coffee.

Almost all the new coffee beans are packed in coarse fiber bags made of jute and pineapple flax, each containing about 60 kilograms. In Hawaii, bags that can hold 45 kilograms are commonly used; in Colombia, 70 kilograms are more popular; and in Puerto Rico, 90 kilograms are sometimes used.

The coffee is then moved to a container that can hold 250 standard bags, or transported on a wooden conveyor. In the process of transportation, pests or moisture will seriously affect the quality of coffee. It is estimated that there are 2250 ships engaged in coffee bean transportation in the world.

China Coffee Trading Network: www.gafei.com