The Journey of Coffee: Harvesting, Drying and Wet Milling Coffee

Coffee, the magical brew that kick-starts our day and keeps us going during those long work hours, has a fascinating journey before it reaches our cups. The journey of coffee: Harvesting, drying and wet milling coffee involves several hundred different people. It begins at the farms with the harvesting of coffee cherries, followed by the drying process, and finally, the wet milling of these beans. Each of these stages plays a crucial role in shaping the flavor and quality of the coffee we love and cherish. Read below to begin to understand why Fratello Coffee Roasters takes so much pride in working directly with coffee producers who are as passionate about growing coffee, as we are roasting it.

Coffee Harvesting: A Closer Look

The harvesting of coffee cherries is the first step in the journey of your coffee from the farm to your cup. This process is much more complex and labor-intensive than it might seem, especially when it comes to high-quality Arabica coffee.

Arabica coffee plants are typically grown in high-altitude regions with a cool climate and rich soil. These conditions are ideal for producing coffee with a wide range of flavors. However, they also mean that the coffee cherries do not all ripen at the same time. In fact, on a single Arabica coffee plant, cherries can be at different stages of ripeness. This poses a unique challenge during the harvesting process.

To ensure the highest quality, Arabica coffee is often hand-picked. This method allows the pickers to select only the cherries that are at the peak of ripeness. Unripe cherries are left on the plant to ripen and are picked during subsequent rounds of harvesting. This selective picking process is labor-intensive and time-consuming, but it is crucial for maintaining the quality of the coffee.

In a single harvest season, a coffee plant can be picked several times. Each round of picking usually takes place every 10 days to two weeks, which is the time it takes for new cherries to ripen. This means that during a harvest season, which can last several months, a coffee plant might be picked over ten times.

The reason for this meticulous, labor-intensive process is simple: flavor. Coffee cherries that are picked at the peak of ripeness have the perfect balance of acids and sugars, which translates into the complex flavors and aromas that are characteristic of high-quality Arabica coffee. Unripe or overripe cherries can have a negative impact on the flavor, which is why they are carefully avoided during the selective picking process.

Drying Green Coffee Beans

Once the coffee cherries are harvested, they are then dried to reduce their moisture content. This is a crucial step, as the right moisture level is necessary to prevent the beans from spoiling and to prepare them for storage and shipping. There are several methods of drying coffee cherries, including:

Sun drying: The cherries are spread out in thin layers and turned regularly to ensure even drying. This process can take up to several weeks.
Machine drying: In regions where the climate is less predictable, or for larger operations, machine drying is used to speed up the process. The cherries are placed in large tumbling machines where heated air dries them.
Combination drying: Some producers use a combination of sun and machine drying. The cherries are sun-dried until a certain moisture level is reached, and then machine-dried to finish the process.

Each of these methods has its own impact on the final flavor of the coffee. For a more detailed explanation of these drying methods, check out our previous post on coffee drying methods.

Wet Milling Green Coffee Beans

After the coffee cherries are harvested and dried, they undergo the wet milling process, also known as the washed process. This is a meticulous and intricate process that plays a crucial role in determining the final quality and flavor of the coffee.

The wet milling process begins with the immersion of the dried cherries in water. Water is not just used for the sake of hydration; it serves a dual purpose. First, it helps in loosening the pulp or the outer skin of the cherries. Second, it acts as a preliminary quality control step. The ripe and high-quality cherries sink in water while the underripe or defective ones float and are removed.

Once the cherries are soaked, they are passed through a depulping machine. This machine is designed to strip off the outer skin and pulp from the cherries, revealing the coffee beans which are still encased in a layer of mucilage. The mucilage, also known as honey, is a sticky, sugary layer that needs to be removed before the beans can be dried.

The removal of mucilage is a delicate process that involves fermentation. The depulped beans are transferred to fermentation tanks, where they are left to ferment in water. The fermentation process can take anywhere from 24 to 48 hours, depending on the climate and altitude. During this time, naturally occurring microbes break down the mucilage, making it easier to wash off.

It's worth noting that the fermentation process needs to be carefully monitored. If the beans are left to ferment for too long, they can acquire a sour taste. On the other hand, if the fermentation is too short, not all the mucilage will be removed, which can also affect the flavor of the coffee.

After the fermentation process, the beans are thoroughly washed to remove the remaining mucilage. This is usually done in washing channels, where the beans are agitated with rakes. The clean, washed beans are then separated from the water by using a series of screens.

The beans are then dried again to bring down the moisture content to a level suitable for roasting. This can be done either in the sun or using mechanical dryers. The drying process can take several days and the beans need to be regularly turned to ensure even drying.

The wet milling process contributes to the clean, bright flavors that are characteristic of high-quality, washed coffees. It's a labor-intensive process that requires a lot of skill and knowledge, but the result is a coffee that is often considered superior in terms of its clarity and flavor profile.

Conclusion

The journey of coffee from the farm to your cup is a complex and fascinating one. Each stage of harvesting, drying, and wet milling plays a crucial role in creating the flavors and aromas that we associate with our beloved brew. So, the next time you sip your coffee, take a moment to appreciate the journey it has taken to reach you.

Dry Milling Green Coffee and Its Significance on Quality

As coffee connoisseurs and enthusiasts, we understand the value of sourcing premium beans, acknowledging the farm's cultivation conditions, and appreciating the initial stages of processing. However, the significance of dry milling green coffee is an often overlooked yet crucial part of the coffee supply chain. This stage, known as dry milling in green coffee production, significantly influences the final quality of our beans. Let's embark on a journey to explore this less charted territory to better understand its significance on quality.

Understanding Dry Milling in the Coffee Industry

Dry milling is a pivotal stage in the coffee processing chain that takes place after coffee producers have picked and dried their coffee using several unique processing techniques. At this stage, the parchment coffee (coffee beans still encased in a protective husk) undergoes hulling, grading, and sorting before export.

This process typically takes place in a facility separate from the coffee farm, known as a dry mill. It's an essential step that bridges the gap between the coffee farms and the roasters, ensuring that only the highest quality beans make it through. The dry mill is where the final touches are put on the coffee beans before exporting to coffee roasters all of the world, refining them into the product that will eventually be roasted, ground, and brewed.

Hulling: This is the process of removing the dried husk from the coffee bean, a crucial step in ensuring the cleanliness of the bean.
Grading: After hulling, beans are graded based on their size, weight, and shape. This ensures uniformity, which is essential for the roasting process.
Sorting: The final stage involves sorting the beans to remove any defective ones, often using a combination of manual and automated methods.

By understanding the importance of dry milling in the coffee industry, we can better appreciate the journey that each coffee bean takes from the farm to our cup, and the many steps along the way that contribute to the final quality and flavor of our coffee.

Dry Milling's Impact on Our Roasting

As coffee roasters, the quality of our final product significantly depends on the dry milling process.

Flavor Consistency: Well-milled coffee ensures each batch we roast has consistent flavor profiles, maintaining our brand's reputation for quality.
Reduced Waste: Efficient sorting at the dry mill stage reduces the chance of roasting defective beans, saving time and resources.
Roasting Precision: Uniformly sized and dense beans allow for precise control over the roasting process, providing the ability to unlock the bean's full flavor potential.

The Indispensable Role of Dry Milling in the Coffee Supply Chain

Dry milling might seem like a routine, mechanized process, but it's much more than that. It's the last opportunity to ensure only the best beans make it to our roastery.

Removing Defects: The Human Touch and Advanced Technology in Dry Milling

Even with the best harvesting and wet milling practices, defective beans can sometimes make it through to the dry milling stage. These defects can include beans that are too small, cracked, or discolored, among other defects and issues.

One of the most traditional methods for removing these defective beans is manual sorting. In many dry mills, workers stand by a conveyor belt, meticulously inspecting the beans as they pass by. These skilled workers can quickly identify and remove defective beans, ensuring that only the highest quality beans make it to the roasting stage.

However, manual sorting is not the only method used in modern dry mills. Advances in technology have led to the development of automated sorting machines that can quickly and accurately identify and remove defective beans. These machines use a variety of methods, including color sorting technology, which uses cameras and optical sensors to detect discolored or otherwise defective beans.

These technologies, combined with the skilled eye of a human sorter, ensure that only the highest quality, defect-free beans make it to the roasting stage. This rigorous defect removal process is a testament to the importance of dry milling in the production of high-quality coffee.

Another technology used is size grading machines, which separate beans based on their size. This is important because smaller beans can roast faster than larger ones, leading to an uneven roast if not properly sorted.

Ensuring Uniformity: The Role of Oliver Gravity Separators in Dry Milling

Uniformity in coffee beans is a critical factor in achieving a consistent and high-quality roast. This uniformity is achieved through grading the beans based on their size and density, a process that takes place during dry milling.

One of the machines commonly used in this process is the Oliver Gravity Separator. This machine separates coffee beans based on their density, a property that is directly related to the quality and flavor potential of the beans.

The Oliver Gravity Separator works by creating a fluidized bed of coffee beans. The denser beans sink to the bottom of this bed, while the less dense beans rise to the top. This separation allows for the removal of less dense, potentially lower-quality beans, ensuring that only the best beans make it to the roasting stage.

The importance of this process cannot be overstated. Beans of different densities roast at different rates. If a batch of coffee includes beans of varying densities, the result can be an uneven roast, with some beans over-roasted and others under-roasted. This inconsistency can lead to a final product with a mix of flavors, detracting from the overall quality of the coffee. By ensuring uniformity in bean density, we can achieve a more consistent roast and, therefore, a more consistent flavor profile.

The Role of Screen Size in Dry Milling

Screen size is another crucial aspect of the dry milling process. Evan after all of the above work, the coffee beans are passed over a series of screens with different sized holes. These screens effectively sort the beans based on their size, a process known as screen sizing. Screen sizing is important for several reasons:

Uniformity in Roasting: Similar to the importance of density, beans of different sizes roast at different rates. Larger beans take longer to roast than smaller ones. If a batch of coffee includes beans of varying sizes, the result can be an uneven roast, with some beans over-roasted and others under-roasted. By ensuring uniformity in bean size, we can achieve a more consistent roast and, therefore, a more consistent flavor profile.
Quality Control: Screen sizing also serves as a method of quality control. Beans that are too small may be immature and could negatively affect the flavor of the coffee. By removing these beans during the screen sizing process, we ensure that only the highest quality beans make it to the roasting stage.
Market Grading: Screen size is often used as a grading method for green coffee beans in the marketplace. Beans are categorized into different grades based on their screen size, with larger beans generally considered to be of higher quality.

Incorporating screen sizing into the dry milling process is another way we ensure the quality and consistency of our coffee. By paying attention to every detail, from the size and density of the beans to the removal of defects, we can deliver the ultimate coffee experience to our customers.

Dry Milling - The Unsung Hero of Coffee Production

The dry mill might be the unsung hero in the coffee supply chain. It plays a vital role in maintaining quality and consistency in every cup of coffee. As coffee roasters, understanding and recognizing the value of this step ensures we can source the best beans, roast them to perfection, and deliver the ultimate coffee experience to our customers. By shedding light on the importance of dry milling, we hope to elevate the appreciation for this critical stage in coffee production.

Shade Grown Coffee and Its Role in Coffee Production

One of the most popular beverages worldwide is coffee, which boasts a distinctive and complex flavour profile. But many coffee drinkers might not be aware that a variety of environmental elements, such as elevation and longitude, have an impact on the quality of the coffee they enjoy. The interaction of these elements may significantly affect the development, maturation, and general quality of the coffee beans. Understanding the relationship between elevation, longitude, and shade grown coffee is important when simply looking at these terms exclusively alone.

Why is the Elevation of Coffee Farms Important?

Elevation and longitude have a significant impact on the quality of coffee. Elevation affects the temperature and other environmental factors that influence the growth of coffee plants. Coffee plants grow best at specific temperatures, and too much heat or too much cold can negatively impact the quality of the coffee beans. At higher elevations, temperatures are typically cooler, making high elevation coffee-growing regions ideal for growing high-quality coffee.

Coffee farms located near the equator are often located at elevations of over 1500 meters, while coffee farms further away from the equator, such as in Central America, are typically located at elevations of around 1100 meters. This difference in elevation is due to a combination of factors including tectonic activity, global weather patterns, and the intense solar radiation at the equator. We go deeper into this conversation about High Altitude Coffees in an older blog post “High Altitude Coffee : What’s The Big Deal”

Why is Shade Grown Coffee Important?

Cloud cover, which offers natural shade and aids in temperature regulation, frequently benefits coffee farms located at higher elevations nearer the equator, thus negating the need for shade trees. This cloud cover is caused by moist air rising from the nearby lowlands coming into contact with the chilly, high-altitude air and condensing into clouds. In contrast, coffee plantations farther from the equator and at higher elevations, like those in Central America, may require the utilization of shade trees to control the temperature and provide a better environment for coffee growth.

It is crucial to remember that while shade and temperature regulation are crucial for coffee quality, other elements like soil quality, the local microclimate, and coffee varietal also affect how best to grow coffee. It depends on the exact region and its particular environmental elements whether shade trees are required or not. Depending on the region, several things are considered "high elevation" for coffee region.

The regulation of temperature and shade are essential factors in determining the quality of coffee. At higher elevations, coffee plants are exposed to cooler temperatures and more moderate climate conditions. The coffee cherries may grow slower and mature over a longer length of time as a result, giving the coffee beans more time to develop their intricate flavour and aroma characteristics. The general temperature of the farm trees would be too cold to grow coffee if these places also have shade trees.

However, excessive sun exposure can result in overheating of the coffee plants, which can harm the coffee beans and lower the quality of the resulting brew. Additionally, because coffee plants require a constant temperature to survive, excessive temperature variation can stress plants, which lowers the coffee's overall quality. Shade trees are used in some areas to help control temperature, lessening the effects of heat stress on coffee plants.

The use of shade trees in coffee production has other benefits as well. Shade trees provide habitat for beneficial insects, birds, and other wildlife, which can help to maintain a healthy ecosystem in the coffee growing region. They also help to conserve soil moisture and improve soil fertility, further improving the overall quality of the coffee.

In conclusion, the use of shade trees in coffee cultivation aids in temperature regulation and guards against overheating, minimizing the effects of heat stress on the coffee beans and enhancing their quality. In addition to offering shelter for wildlife, shade trees preserve soil moisture and fertility, which benefits the ecosystem's ability to grow coffee.