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 picker

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.

high altitude coffee farm

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.

ripe coffee cherries

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:

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.

drying coffee beans

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.

wet mill

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.

wet mill

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.

drying coffee beans

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.

Density sorting machines

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.

Green coffee defect chart

 

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.

Optical sorting machine

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.

Density sorting machines

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.

green coffee screens

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:

green coffee hand sorting

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.

Bolivian Buena Vista: A Journey of Quality and Sustainability

Embark on a journey to the heart of Bolivia and discover a journey of quality and sustainability, and learn more about why we love with our Bolivian Buena Vista coffee offering. This narrative takes you through the intricate processes of coffee production, from the nurturing of coffee plants to the meticulous processing of coffee beans. It's a story of dedication, hard work, and a deep commitment to quality and sustainability, a story that brings to life the rich flavors and aromas of Bolivian coffee.  Try it for yourself now. 

Bolivian Coffee Farm

The Sol De La Mañana Program

The Sol De La Mañana program is a remarkable initiative that aims to elevate the Bolivian coffee culture and diversify its offerings. This program is designed as a comprehensive school for local coffee producers, taking them on a 7-year journey to graduate as skilled coffee farmers. Taste this coffee for yourself and discover 

The curriculum of this program is extensive, covering every aspect of coffee farming. It starts with the basics of setting up a nursery, moves on to planting, and then guides the producers through the stages of harvesting, pest prevention, and pruning. But it doesn't stop at farming techniques. The program also imparts crucial knowledge about financial management, enabling the producers to run their farms as successful businesses.

The Sol De La Mañana program is a collaborative effort. Leveraging the knowledge acquired through Fincas Los Rodriguez, the program works with around 100 producers, helping them enhance the quality and quantity of their farms. This not only improves the coffee production but also contributes to a better life for the producers and their families in the long term.

Bolivian Coffee Producer

The Journey of Bolivian Coffee

Caranavi is the processing hub where most of the coffee processing work is done. Every evening, their wet mill buzzes with deliveries from their farms and the producers' farms. Each bag of coffee cherries gets weighed and processed immediately. The processing involves washing, fermenting, or moving the cherries to dry as naturals. They use raised beds and machine drying to dry the beans on site before sending them to their dry mill for quality control, packing, and exportation. Quality is checked at every step of the way, and each processed lot gets cupped on site to ensure it meets their standards.

Russ Prefontaine

Bolivia Buena Vista Coffee Mill

The Buena Vista Mill, located in Caranavi in the region of La Paz, is where they receive coffee from their own farms, Sol De La Mañana farms, as well as different farmers in the area. This year, they are excited to announce their collaboration with Agricafe.  Agricafe works with around 500 different farmers to collect coffee from all over Bolivia and bring it to their wet mill in Caranavi in cherry form. This is the best of Bolivian Coffee.

The coffee makes the trek from up to 4 hours away down the mountains to Caranavi every evening by taxi. Agritcafe pays top dollar for only the finest coffee coming from the farms and also pays for the transport by taxi so that there are no additional expenses incurred by the farmers. Once at the Wet Mill, it is then sorted by hand to ensure only the best cherries get through. This is on top of the meticulous sorting that the farmers have done before it is ever put in the taxi.

Raised African Drying Beds

Bolivia Agricafe Processing and Quality Control

One of the most interesting things about this wet mill is how many options they have to process the coffee. They have 6 fermentation tanks, 3 mechanical driers, a concrete patio, African raised beds, and Covered African raised beds. This helps ensure that each coffee is processed exactly the best way to bring out the flavors that their customers request.

After processing and drying, the coffee is stored in Caranavi in a temperature-controlled room for 2 months before being shipped to the dry mill at El Alto. The dry mill is mostly a typical dry mill, where they remove the parchment, run the coffee through density shakers, and finally, it is hand sorted to make sure no damaged beans get through. The unique feature of this dry mill is the black light sorting it goes through. As it is being hand sorted, it passes through these black light tents where imperfections that are previously invisible to the eye are shown as little white dots. Although not a-defect in the coffee, this coffee is removed, which increases the clarity of the cup, making the flavors of each particular coffee pop out more and become more exciting.

At every step of the process, the coffee is cupped to ensure that the product is still what was agreed upon at the time of purchase.

Covered coffee drying beds

Overcoming Challenges

One of the biggest challenges in sourcing good Bolivian coffee is the small size of the farms. With most farms being 3 to 8 hectares, it becomes difficult to find quality coffee in the quantity needed by just dealing with individual farms. This is where Agritcafe comes in. With the ability to work with over 500 farms and find the best coffee from all of those and then pass on this quality, it makes it significantly easier.

For instance, this year they will be buying from 5 different farms that Agricafe works with and has a good standing relationship with already. So instead of hunting down these farms from all over Bolivia, they now have it much easier because of Agricafe. They are looking forward to working with Agricafe in the coming years; it is their hope that next trip down to Bolivia the farms that they are buying from this year will continue to be as good or better so that they can develop more of a relationship with the farmer. If they can find this kind of consistency, they can then start playing with processing types to create the best and most interesting coffee for their customers. They believe they have already found the best Bolivia has to offer and through their continuous improvements in milling and experimenting, they expect it to get even better.

Agricafe drywall

The journey of Bolivian Buena Vista coffee is a testament to the dedication, hard work, and commitment to quality and sustainability of the local producers and the teams at Agricafe and the dedication of the Rodriguez family. It is a story of passion for coffee, respect for the land, and a deep commitment to improving the lives of the local farming community. As customers sip their cup of Buena Vista coffee, they not only enjoy the rich flavors and aromas but also become a part of this beautiful journey.

bolivia buena vista bag

Coffee Processing Methods Explained : Natural, Anaerobic, Honey, Oh My!

Are you starting to get serious about specialty coffee? It’s essential that you learn about all the different coffee processing methods.

You know when you look at a bag of coffee and see “black honey” or “anaerobic natural”? Our aim is to help you end this head-scratchery so you can be confident about your coffee knowledge.

We did a previous blog about coffee processing before, but we wanted to revisit it more in-depth and add some newer processes to the mix. Understanding how your coffee was processed helps you understand why it tastes the way it does.

Natural Processed Coffee

What is coffee processing?

In a nutshell, coffee processing is what gets done to the coffee cherry after it’s been picked off the tree and sorted. After harvesting and picking the ripest cherries, the producer needs to decide what to do with the cherries.

Coffee is the seed inside of a cherry. Sure, you could simply remove the cherry and discard it immediately. That is a coffee processing method in itself (more on that later). But the cherry itself is sweet and fruity, and it can add some very interesting, complex flavours to the green beans.

In most forms of processing, a certain amount of the cherry pulp is left on the bean to ferment. Fermentation is a tricky task which can go terribly wrong and result in spoilage, but if done right, it can be magical. It requires getting the right temperature, pH level, and fermentation time.

Layers of a coffee bean

 

The anatomy of a coffee cherry

Let’s run through the anatomy of a coffee cherry so that when we throw around terms like “mucilage” and “skin,” you know what we’re talking about.

The skin or the “cascara” of the cherry is the outermost layer of the fruit.

The pulp refers to the overall flesh of the fruit, just under the skin.

The mucilage is a very specific part of the pulp–it’s the sticky, slippery layer that covers the seed.

The parchment is the papery layer of the seed that covers and protects the seed. It comes off naturally while being roasted.

The seed of the coffee cherry is essentially the green bean.

To better visualize the anatomy of a coffee cherry, check out this resource

Let’s run through the most popular coffee processing methods.

fully washed coffee

Wet process coffee

Wet process coffee, or “washed” process, is a process where the pulp and mucilage are removed from the seed as quickly as possible. 

First, the coffee cherries are placed in a de-pulping machine. Second, the seeds ferment briefly to soften the mucilage just enough to facilitate easy removal. Third, the seeds are soaked in water and agitated to remove the sticky mucilage layer. Finally, the seeds are laid flat on beds to sun-dry completely before being packed and shipped.

This is a very popular method of processing because it lends a very clean taste that allows the natural acidity to shine.

honey processed coffee

 

Honey process coffee

In the honey process, the skin and pulp are removed from the seed, but the mucilage is left on the seed during fermentation.

There are 3 different levels of honey process coffee: yellow, red, and black. The darker the colour, the longer the fermentation, and the stronger the flavour. Let’s explore these sub-processes more in-depth.

The mucilage is left on the seed, and the beans are laid out on large mats to sun dry. Yellow honey process coffee is lightly sweet and fruity with a clean profile, similar to wet process, but fruitier.

The mucilage-covered seeds are fermented slightly. The seeds are piled on top of each other to facilitate fermentation, and then raked into a flat layer to dry. Red honey coffee tastes sweet and fruity.

In this process, the mucilage-covered seeds are fermented the longest. The beans are piled on top of each other, with a longer fermentation than red honey. Black honey process coffee tastes winey and boozy thanks to the longer fermentation, with ripe fruit notes. 

 

natural processed coffee

Natural process coffee

Natural process coffee is where the whole cherry is left intact on the seed during fermentation. This includes the skin, pulp, and mucilage–nothing is removed. 

The beans lie in the sun on raised beds, while constantly being turned. This prevents rotting and spoiling the entire batch of coffee. Once the beans are fully dried, the dried cherries are hulled off to extract the green beans.

Natural process coffee has a very fruity, molasses-y flavour that a lot of people are drawn to. It’s common to taste fruity notes like blueberry, strawberry, and raspberry, with a pleasant acidity.

The natural process is popular in coffee-growing countries where clean water isn’t an abundant resource. You’ll tend to see natural process coffee from countries like Ethiopia where there isn’t a huge supply of clean water.

Anaerobic process coffee

The anaerobic process is a newer process that’s quite tricky and time-consuming. When done properly, it can have incredibly exciting, exotic flavours like tropical fruit and spice.

Anaerobic means “oxygen deprived.” The intact coffee cherries are placed in large barrels with water and sealed from oxygen for 48 to 72 hours. They ferment without oxygen, which imparts  a completely different flavour from natural or honey processing. After fermentation, the pulp and mucilage are removed and the beans are laid to dry completely in the sun.

Raised African Drying Beds

Wet hull process

Not to be confused with “wet process,” the wet hull process is a less common type of coffee processing. Also known as “giling basah,” this coffee process method is mainly practised in Indonesia. In this process, the parchment is removed from the seed before the bean dries completely.

Coffee that’s been wet hulled tends to have rich earthy, smokey, dirty flavours, with little to no sweetness or acidity. These coffees tend to taste good when roasted dark, which eliminates some of their unpleasant flavours. This allows the desirable flavours, like earth and smoke, to shine. 

Trust the process

Coffee processing methods have a huge impact on the flavour of your coffee. If you’re a coffee lover and want to learn more about coffee, it is essential that you learn about coffee processing methods. It can help you understand why your coffee tastes the way it does.

Want to experience coffee processes for yourself? Shop our Kenya Fully Washed, our West Coast Honey Processed, or our Gunsmoke Fully Washed & Wet Hulled coffees now!

 

The Effects of Drying Speeds for Green Coffee

Nothing is more rewarding then seeing a fresh crop of micro-lots being unloaded off the back of a truck into our roastery.  This pleases me so much as I know the amount of work our producers and exporters have put into this coffee to get it this far.  I also know how much work we have put into sourcing and choosing these precious beans to offer our clients.  What many don’t know, is how the drying speeds at the farm, can drastically effect the quality and shelf life of the green beans roasters receive.  

 

Nothing is more disappointing then when you begin to sample roast and begin profiling these new arrivals and the flavor profiles we tasted at origin are no longer being tasted.  “What is going on!?!?  How can a coffee taste so different at origin compared to what we are tasting now?”   This isn’t unique to Fratello, and is something we have heard many roasters around the world talk/complain about.  It has been a topic of many conversations over the past year with the coffee producers we work with and exporters who are working on the ground at origin every day.

My first major experience with this coffee was 2 years ago when we purchased an incredible micro-lot from Acevado Huila, Colombia.  This 20 bag lot was scored a 91.00 at origin by myself and the others we were with that day.  It was an outrageous coffee, and we paid top dollar for it.  By the time we received this coffee 3 months later, it was extremely faded.  We were getting cupping notes of wood/twigs and it almost tasted like a past crop coffee.  The moisture content was accurate and the processing seemed perfect.  We ended up not selling this coffee to anyone.  It was a total waste of our time and re-sources.  So what went wrong?

6 months later we visited this coffee producer again and began asking questions about how they dried their coffee.  In Colombia it is normal for producers to use a Parabolic drying bed (similar to a green house).  These are perfect for protecting the green beans from the elements; however, it can also produce high levels of heat when not used properly.  Unfortunately, this producer was not, and was drying their coffee in 3-4 days.  This is WAY too fast.  Typically, a producer would want to slowly dry their coffee over a 12-18 day time frame for an even consistency throughout the bean.    What we are learning is when you dry your coffee too quickly; it is hard to read the correct moisture level in your green beans accurately.  The extreme heat forces the water content into the beans giving a false reading in your moisture meters.  You may show a moisture reading of 11-12% (which is the goal), but as these beans sit, the moisture that was forced into the bean, will migrate back out to the surface over time.  The end results are beans being pulled from the drying beds much to early, giving an unstable bean, which has potential fermentation and accelerated fading in flavors.

Another example is in El Salvador we had purchased an award winning Pacamara (large bean).  It was extremely sweet, with an orange syrupy body, maple flavors and very clean.  On arrival in Calgary, we found some of the same faded, twiggy notes coming through in the cup.  Again, a huge disappointment.  With research we found that the drying time was 5-7 days, which was much too fast for such a large bean.

In speaking with our producers the biggest challenge they face is the changing environment.  It is getting hotter and more intense each year.  They never had these issues in the past of drying the coffee this quick and now have to re-think their processing techniques.  Creating systems that help them slow the drying times employing shade barriers and different cooling techniques.  All of this takes time and often a lot of money to re-create their drying beds.  More and more often we see raised African beds with shade cover being installed and used on our top micro-lots.

This then brought my attention to the mechanical drying systems installed at MANY large and micro-mills around the world.  They are becoming very common, as coffee must be dried once it is de-pulped after harvesting.  If the sun isn’t out due to rain, the coffee will need to go into dryers.   These dryers work very fast, and often only take 1 day to finish the drying.  This drying technique is not only fast; it consistently dries the bean through out.  Is this the best route?

Studies are now showing that the ideal drying conditions for coffee require the slow drying technique.  What this allows are some resting periods for coffee.  When heat is on the beans, the cellular structure opens, when the temperatures drop, the cells close…. almost like it is breathing.  This has shown to create a harder cellular structure on the bean that enhances acidity and gives better conditions when roasting.  The fast drying speeds in the mechanical system never allow for resting, giving a softer cellular structure and less acidity in the final cup.

This short blog post barely scratches the surface on drying techniques and does not answer or explain everything processing technique (Naturals, pulped naturals, honey’s, etc…), but has simply been written to bring some awareness to a subject not often discussed.  We have some much more to learn, and together with the producers will continue to push the limits of processing, exporting and roasting the best coffee in the world.

Coffee Processing: What gives coffee unique flavors?

harvesting red coffee cherries

This is an interesting question, and one that does not have a quick answer.  I often compare coffee to wine as there are many comparables.  All bottles of red wine from Italy do not taste the same.  It is dependent on the vineyard, the grape (Merlot, etc..), the harvest, soil conditions, altitude, weather conditions of that particular harvest in that particular year, in that particular region.  All of this is also true with coffee.

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