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Why is The Classification of Cherries Essential to Improve the Quality of Coffee?

improve the quality of coffee

Growing high-quality coffee requires great skill and attention to detail. Beyond implementing best agricultural practices, harvesting and sorting cherries are essential parts of the process to improve the quality of coffee. Many farms choose to pick and sort cherries manually. Some even have no choice but to harvest them by hand; However, these methods can be laborious and time-consuming, resulting in higher costs for producers.

As a result, some coffee growers are turning to mechanized solutions to harvest and sort cherries to improve quality. To find out more, I spoke with Carlos Henrique Palini, commercial director of Palinialves , and with Felipe Fernandes Vilhena Faleiros, operational manager of Eldorado Specialty Coffees.

How do pickers harvest and sort cherries?

Harvesting and sorting cherries are two essential steps in coffee production. Farmworkers can use several different methods to do both, including manual, semi-mechanized, and fully mechanized.

Carlos works at Palinialves , a Brazilian agricultural equipment manufacturer. He explains that the ripeness of the cherries is a key factor in all three picking and grading techniques.

It is necessary to harvest coffee cherries at the optimal state of maturity and uniformity, with a higher percentage of ripe fruits or red cherries.” he says.

Selective harvesting helps coffee farms achieve this. Workers hand-pick only the ripest cherries, which helps improve quality and increase sweet, complex flavors ; However, this method is labor intensive.

Meanwhile, some farms use manual strip picking . There, workers harvest all the cherries on the branches by hand.

Mechanized harvesting methods

One of the most common semi-mechanized harvesting techniques is when farm workers use hand tools called derricadeiras to shake and pluck cherries from the branches. The cherries then fall onto tarps located under the plants to facilitate harvesting.

Felipe works at Eldorado Specialty Coffees , a group of farms in Brazil. He says his growers wait for the cherries to reach around 75% maturity before harvesting them using mechanized systems.

On larger farms located on flatter terrain, such as in Brazil, producers use specialized machinery to pick cherries. Workers drive large mechanical harvesters that have rotating and vibrating rods to shake the cherries and collect them into bins.

Whether done by hand or machine, strip picking can save time and money but removing green cherries from harvested lots can be arduous.

During harvest it is common for pickers to remove underripe and overripe cherries, as well as ripe ones. The first two must be eliminated to maintain the quality of the coffee.

Through post-harvest processing, the ripe cherries are separated.” explains Carlos. “This improves uniformity of maturity to increase quality.”

What about the classification of coffee cherries?

Carlos says that the process of sorting cherries involves various equipment and techniques to achieve optimal ripeness. Many farms begin by placing the harvested cherries on a tarp and removing those that are not ripe. Others use automated systems to sort cherries by size, color and density.

In certain cases, cherries are placed in water tanks to identify defective, underdeveloped or overripe cherries, which float to the surface and are then removed.

Farmworkers then visually inspect the coffee as it dries in carts or yards to identify and remove damaged, insect-infested, discolored, or underripe beans.

After a drying period of approximately two months, producers use a density classifier and gravity separator to distinguish high- and low-density beans . Denser beans are generally considered to be of higher quality and often sell for higher prices.

Finally, the green beans are sorted by color to remove defective beans, either by hand or by machines with sensors. This step is crucial to ensure that the coffee meets specialty quality standards.

Problems associated with manual classification methods

Although manually sorting coffee can help with quality control, this method is often time-consuming and not always the most accurate.

Due to the size of our farms and the volume of coffee harvested daily, sorting cherries manually is inefficient and expensive” says Felipe.

It can take a team of people hours to meticulously sort cherries by hand . The longer this process takes, the more likely the cherries will become overripe and spoil. Selective picking can take even longer as not all cherries ripen at the same rate, so workers must harvest multiple times.

To increase productivity, coffee farms must employ large equipment, so costs can grow quickly.

On the other hand, most coffee-producing regions in Brazil are currently suffering from labor shortages” explains Felipe. This creates a number of problems, including overripe cherries and poorly selected coffee, ultimately resulting in lower yields and lost profits.

Additionally, collectors often rely solely on color as an effective way to assess maturity levels but this process can be subjective. Additionally, sorting yellow cherries can be especially difficult because it is more difficult to know when they have reached optimal ripeness.

Manual sorting is an even greater challenge for larger producers because they have larger planted areas and a greater volume of coffee at different stages of ripening. This results in an even greater lack of uniformity” says Carlos. “In turn, larger farms require more robust post-harvest infrastructure to separate and sort coffee cherries.”

Increasing use of mechanized sorting systems

Producers with the means and resources to decide must weigh the pros and cons of manual and mechanized sorting solutions. As it becomes more difficult each year to find a stable workforce in some producing countries, an increasing number of farms have begun to rely on automated solutions.

One of them is Palinialves ‘ FullSelect optical sorter , which was displayed at the company’s booth at the International Coffee Week 2023 event in Belo Horizonte, Brazil, from November 8 to 10.

Carlos explains how the machine works. “The FullSelect is an electronic optical sorter that separates coffee cherries according to color,” he says. “Farm workers feed the harvested cherries (which are at various stages of ripening) through a hopper. They are transported on a conveyor belt to the optical sorting machine.”

“The machine uses high-resolution cameras to take photographs of the cherries and distinguishes them by color sensitivity,” he adds. “For example, red or yellow cherries are accepted, while green and black cherries are rejected.”

When FullSelect identifies defective cherries, a stream of high-precision compressed air moves them and separates them from the ripe cherries.

“The optical sorter is also equipped with a set of full-color cameras that can detect green coffee in ripe red cherries,” says Felipe. “These cameras are very sensitive and can classify cherries with a high level of accuracy based on subtle differences in color tone.”

Consider the context of each producer

Despite that, it is important to keep in mind that not all farmers need to use mechanized harvesting or sorting machines. For example, it is potentially more profitable for small producers growing coffee on one or two hectares to harvest and sort cherries by hand, mainly because they produce small volumes of coffee.

Additionally, some farms may be located at higher altitudes or in mountainous terrain, making it difficult for harvesting machines to operate. Additionally, some producers may not have the capital or access to loans to invest in these solutions.

How do sorting machines benefit producers?

Of course, the most obvious advantage of using mechanized sorting solutions is saving time and money. Instead of meticulously sorting cherries by hand, growers can use machines and focus on other areas of their farm.

Mechanized sorters like FullSelect are much more reliable than manual methods and allow me to free up more time.” explains Felipe.

Using these machines can also increase production volumes more effectively.

Carlos points out that “manual sorting methods usually have high operating costs but result in lower yields.” “Optical sorters can process between 6,000 and 10,000 kg of coffee cherries per hour, significantly more than the volume that pickers can sort by hand.”

Carlos adds that sorting machines also offer other benefits to producers, particularly those who focus on growing higher quality coffee.

“The Palinialves FullSelect machine , for example, can sort large volumes of cherries efficiently and accurately,” says Carlos. “This way, growers can process only the ripest cherries and therefore raise overall quality.”

Greater focus on quality can improve the quality of coffee, enhancing the overall experience for consumers.

For producers who have the resources to invest in mechanized sorting solutions, post-harvest processing methods can become more accessible and optimized.

The FullSelect machine is simple to operate and can be configured using an intuitive touch screen panel” explains Carlos. “Also, it has automatic sensitivity adjustment.”

Additionally, this more advanced technology means that farmers can dedicate more time and energy to other aspects of their business to further improve coffee quality.

“With the use of mechanized sorters I am sure that I will only process ripe red cherries without defects,” concludes Felipe.

From planting the seeds to implementing various processing methods, producers who grow high-quality coffee certainly don’t underestimate any step of the process. Against this backdrop, many farmers around the world rely on manual methods of harvesting and sorting, and some have no choice but to do so.

At the same time, it appears that more and more producers have begun to see the benefits of using mechanized sorting solutions. For coffee farms that have the infrastructure and resources to invest in them, these machines can provide a wide range of benefits.


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