Coffee lovers welcome the smooth, rich aroma of the morning brew. The journey from coffee tree to flavorful cuppa Joe is a captivating story of process and progress. A globally popular beverage, coffee continues to rise in prominence to a distinct artisan creation.
Coffee flowers and fruits or cherries grow on small evergreen trees or shrubs. If left unpruned, coffee trees can reach up to 5 m (16 ft). Most farmers trim them each year to a height of 1.5 - 2 m (5 to 7 feet) for easier harvest.
Coffee Varieties
Flavor starts with species. Coffee varieties are the different subspecies obtained through selective breeding or natural selection of coffee plants. Most coffee comes from two main groups, Coffea arabica and Coffea canefora (aka C. robusta).
These produce countless variants and subspecies. C. canefora beans have a lower acidity, increased bitterness, and a woodier, less fruity taste in comparison to C. arabica beans. The majority of C. canefora beans are used in instant coffee.
Despite the vast diversity found in both wild and cultivated coffee plants, only a few varieties and cultivars hold commercial significance. This is due to their distinctive and inherent characteristics, such as disease resistance and fruit yield.
Producers choose breeds based on these traits when developing crops. Thus, from the very beginning, selecting the right breed is crucial is a vital factor in determining cup quality and flavor blends. This is good info to know and could help determine the right blend for you.
Start With the Soil
Even the pH level of the soil, which indicates acidity or alkalinity, directly affects the flavor of coffee. Neutral pH soils yield coffee with a more balanced flavor, whereas acidic soils often yield beans with bright and tangy notes.
Coffee soils can be sandy loam or rich in clay. The texture of soil influences nutrient absorption. Clay and organic soils retain nutrients better than sandy loam. Soils high in nitrogen (acidic soil) and ammonia or ammonium (alkaline) produce healthier plants.
Ammonia (NH3) and ammonium (NH+4) are created by nitrogen-fixing bacteria. They live in the roots of the tree or nearby legumes and transform nitrogen in the soil, which the plants can't uptake, into compounds they can easily absorb.
In nature ammonia also comes from anaerobic decay of plant and animal matter by fungi and bacteria, such as acetic acid bacteria. These organisms use nitrogen, phosphorus and other nutrients to live and grow.
They reduce nitrogen to organic acids and ammonia. Ammonia has a slightly sour taste. Plant leaves absorb high quantities of ammonia from the air, even at low concentrations. These elements influence the flavor of coffee creation from the roots of the earth herself.
Coffee Harvesting
Coffee trees or bushes cherish lush, tropical climates, like the torrid zone between the Tropics of Cancer and Capricorn. Coffee plants like Arabica and Robusta prefer altitudes from 600 to 2,000 meters (1970 - 6600 ft).
Coffee production is prolific in equatorial regions like Colombia, Ecuador and Brazil. Southern Africa and tropical Asia are major producers. Vietnam produces about 90% of the Robusta on the global market.
After about 5 years of growth, coffee plants bear fruits known as cherries. On the stem they rarely all ripen at the same time. Bright red coffee cherries are ripe and ready for picking.
Underneath the cherry's outer skin is a thin layer known as the mesocarp, more commonly the pulp. The inner part of the pulp is the mucilage. Beneath the mucilage is another layer of pectin. These layers are rich in sugars, which are essential to fermentation.
When fruits ripen they produce more sugar, usually as glucose and fructose. The increase in sugars attracts wild yeast indigenous to the region. This industrius fungus is accompanied by several other microbial fermenters like lactic acid bacteria.
Coffee is harvested through selective picking or strip picking.
Selective Picking
In this method, only ripe coffee cherries are hand-picked, which is labor-intensive but ensures the highest quality beans, or seeds of the coffee. This approach is important to the coffee drinkers at the end of the process, favoring quality over quantity.
Harvest typically happens once a year. In regions with diverse climates, multiple harvests can take place. Timing is crucial. Cherries must be picked when fully ripe for optimal coffee flavor.
This method collects only the best cherries are collected at the proper stage of ripeness. In Brazil this technique results on average in 40% higher quality coffee compared to strip picking.
Strip Picking
Strip picking harvests all cherries at once, regardless of ripeness. The problem here is obvious. The method is quicker and more cost-effective but causes quality decline and inferior blends or flavors.
This approach is common in large-scale farms but does affect the product. Strip-picked coffee can lose up to 25% of its flavor potential due to mixed ripeness. However in this method flavor is not a priority. The point is production.
Preparation: Cherries to Beans
Once harvested, cherries have to be prepared quickly before spoilage sets in. Microscopic mold also exists on the beans, and given the opportunity it will proliferate, especially in moisture or humid climates, resulting in a spoiled batch.
The preparation process can be done through three main methods: dry method, wet method, and honey process.
Dry Method
In the dry method, or natural processing, cherries are spread out in the sun to dry. This allows the sugars from the fruit to leach into the beans, creating unique flavors. The dried fruit is then hulled to extract the beans. This technique imparts fruity notes and body to the coffee.
Coffees processed this way can have a "sweetness profile". In Ethiopian natural coffees for instance, the natural sugars account for more than 60% of the final flavor.
Wet Method
In the wet method, cherries are depulped to remove the outer fruit layer before fermentation. This process enhances clarity and brightness in the final cup. It's more common in specialty coffees. Colombian coffees often use this method for a crisp and fruity flavor with citrus notes.
Honey Process
The honey process merges aspects of both methods, where some mucilage is left on the beans after depulping. This creates a balance of sweetness and acidity, influencing the intricacy of flavors. Costa Rican coffees frequently use this method.
While the chosen processing method influences coffee flavor, fermentation plays a crucial role in developing the coffee's singular profile.
Fermentation
Fermentation is a critical stage significant to flavor development. During this process, natural enzymes and microbes break down the mucilage, the sticky substance surrounding the beans, in wet processing.
Microbes include wild yeast or introduced yeast, lactic acid bacteria (LAB) and acetic acid bacteria. Lactic acid bacteria include Lactobacillus, Streptococcus Leuconostoc, Lactococcus and Pediococcus. They also drive the fermentation of milk, vegetables, cereals and legumes.
While consuming sugars yeast expels carbon dioxide and ethanol (alcohol). The acetic acid bacteria are here for the booze. They digest alcohol and transform it to vinegar. Acetobacter is a popular genus among vinegar artisans, less so among vintners.
Fermentation uses two main methods.
Controlled Fermentation: Many coffee artisans opt for controlled fermentation, where variables like temperature and time are monitored to achieve optimal flavor notes.
Wild Fermentation: A more natural approach, this lets local yeast and bacteria influence the fermentation. This method can lead to unique flavors reflective of the terroir.
Terroir means “a sense of place.” Terroir comprises all the factors of coffee production, from the climate, soil, elevation, pollinators and wild fermenters. It's also applied to the making of beer, wine and bread. Fermentation lasts between 12 and 72 hours.
During fermentation, the microorganisms break down sugars and develop acids integral to the coffee's aroma and taste. Properly managed fermentation can yield bright, fruity profiles. Poorly managed fermentation can introduce off-flavors truly noxious to connoisseurs.
Roasting: The Flavor Catalyst
Roasting transforms green coffee seeds into the aromatic beans we know and love. This process is an art form itself. Roasting requiring precision and knowing how different roasting profiles influence flavor.
Light Roasts: Retain more of the bean’s original flavors, highlighting the acidity and brightness. Often preferred for single-origin coffees.
Medium Roasts: Balance the flavors between acidity and body, appealing to a broader audience.
Dark Roasts: Develop rich, bold flavors, often with notes of chocolate and caramel. This style can mask some of the original bean's nuances.
Each roast level unlocks specific chemical reactions within the beans, affecting the resulting aroma, flavor, and body. A skilled roaster can bring out the best in each batch.
Three reaction stages happen during roasting. These are drying, browning and development.
The Maillard reaction or browning stage is a chemical reaction between amino acids and reducing sugars, in which main flavor compounds are formed. The Maillard reaction also applies to charred steaks, baked bread crust and roast marshmallows.
Processing Techniques: Beyond Roasting
Grinding is the next significant step, breaking roasted coffee into smaller pieces. The grind size impacts extraction during brewing. For example, a coarse grind is ideal for a French press, yielding a smooth cup, while a fine grind works well for espresso, for a thicker crema.
Brewing significantly influences flavor extraction. From pour-over to espresso and French press, each method brings out different flavor notes and aromas. Using the pour-over technique can accentuate a coffee's floral notes, while French press might enhance its body.
6. Refining Flavors: The Final Touch
For coffee artisans, refining flavors is an ongoing journey. This can include blending different beans to achieve a desired taste profile, using flavored syrups, or incorporating unique brewing methods to accentuate specific notes.
Flavor Profiles: Coffee connoisseurs often analyze aromas and flavors, identifying notes of fruits, nuts, chocolate, or floral qualities. This understanding allows for more intentional pairings with foods and enhances the overall experience.
Sustainability and Ethical Sourcing: Increasingly, coffee artisans focus on sustainable sourcing and ethical practices, which contribute to the quality and sustainability of coffee production. Knowledge of the supply chain fosters a deeper appreciation for the craftsmanship involved.
Coffee artisans experiment with flavor pairing, for instance blending beans from different regions to create a unique profile.
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