This set focuses on specialized equipment, chemical reactions during roasting, and the unique history of coffee in the Kenyan highlands.
Article 131: The Maillard Reaction: Why Coffee Turns Brown
(Category: Roasting Knowledge | Word Count: ~310)
The most important chemical transformation in coffee roasting is the Maillard Reaction. This is the same reaction that gives toasted bread its flavor and seared steak its crust.
It occurs when heat causes a reaction between amino acids and reducing sugars. In coffee, this usually begins around 140^\circ\text{C} (284^\circ\text{F}).
What it Creates:
- Melanoidins: These are the brown pigments that change the bean from green to brown. They also contribute to the “body” and “mouthfeel” of the brewed coffee.
- Aromas: The Maillard reaction produces hundreds of aromatic compounds, including those that smell like nuts, caramel, and savory toasted notes.
If a roaster rushes through this stage too quickly, the coffee will taste “baked” or bread-like, lacking complexity. If they spend too much time here, the delicate floral and fruity acids (which the reaction consumes) will disappear. A master roaster carefully controls the “Rate of Rise” during this phase to perfectly balance sweetness and acidity.
Article 132: The “Cortado” vs. The “Gibraltar”
(Category: Barista Skills | Word Count: ~240)
In many specialty cafes, you will see a Cortado on the menu. The name comes from the Spanish word cortar, meaning “to cut”—referring to the milk “cutting” through the espresso.
The Recipe:
A Cortado is typically a 1:1 ratio of espresso to milk. It consists of a double shot of espresso and roughly 2\text{ oz} (60\text{ ml}) of steamed milk. Unlike a cappuccino, a Cortado has very little foam; the milk is integrated and silky.
The “Gibraltar” Variation:
You may also hear this drink called a “Gibraltar.” This name was coined in San Francisco and refers specifically to the 4.5 oz Libbey Gibraltar glass it is served in. While the ingredients are the same as a Cortado, the Gibraltar glass has become a symbol of Third Wave coffee culture. It’s the perfect drink for someone who wants to taste the strength of the espresso but with a creamy, smooth finish.
Article 133: Why We Use Raised “African” Beds
(Category: Coffee Education | Word Count: ~260)
Kenya is world-famous for its use of raised drying beds, often called “African Beds.” While some countries dry coffee on concrete patios, the raised bed system is superior for specialty quality.
The Advantages: - Airflow: Because the beds are made of wire mesh, air circulates both above and below the coffee beans. This prevents the “musty” or “earthy” flavors that can occur when beans sit on damp concrete.
- Even Drying: It is much easier to control the drying rate. In Kenya, workers often cover the beds with plastic during the heat of the midday sun to prevent the beans from drying too quickly and cracking.
- Visual Inspection: As the coffee dries, workers can easily walk alongside the beds and pick out any “defect” beans (nicks, bites, or discolorations) by hand.
This meticulous attention to detail is why Kenyan coffee consistently scores so highly in international cupping competitions.
Article 134: Understanding “Static” in the Grinder
(Category: Barista Skills | Word Count: ~210)
Have you ever noticed coffee grounds “spraying” out of the grinder or sticking to the sides of the chute? This is caused by Static Electricity.
When coffee beans are crushed between metal burrs at high speeds, friction builds up a static charge. This causes the grounds to repel each other and stick to everything else. Static is usually worse when the air is dry or when the beans are very fresh (containing more CO_2).
The “RDT” Trick:
Specialty baristas often use the Ross Droplet Technique (RDT). This involves adding a single tiny drop of water (or a quick mist from a spray bottle) to the whole beans before grinding. The moisture neutralizes the static charge, ensuring the grounds fall neatly into the portafilter without clumping or making a mess.
Article 135: The Anatomy of a Coffee Tree
(Category: Coffee Education | Word Count: ~290)
The Coffea Arabica tree is a woody perennial evergreen. Understanding its structure helps baristas appreciate the labor involved in farming. - The Taproot: A deep central root that can grow up to 1\text{ meter} deep, seeking out nutrients and stability in the volcanic soil.
- Verticals and Laterals: The tree has a main vertical trunk and horizontal “lateral” branches. Coffee cherries only grow on the lateral branches.
- The Leaves: Waxy, dark green leaves. They are the “solar panels” of the tree. If the leaves are covered in dust or damaged by “Leaf Rust” fungus, the tree cannot produce enough sugar for the cherries.
- The Nodes: The points on the branch where the flowers and cherries grow. A healthy Kenyan tree will have “clusters” of 10\text{ to }20 cherries at each node.
In Kenya, trees are often “stumped” or pruned heavily every few years to encourage new growth and keep the cherries within reach for hand-picking.
Article 136: What is a “Lungo”?
(Category: Barista Skills | Word Count: ~220)
A Lungo (meaning “long” in Italian) is an espresso shot that is pulled for a longer time, using more water.
The Difference: - Standard Espresso: 1:2 ratio (e.g., 18\text{g} coffee to 36\text{g} liquid).
- Lungo: 1:3 or 1:4 ratio (e.g., 18\text{g} coffee to 54\text{g} or 72\text{g} liquid).
The Flavor Profile:
Because more water passes through the grounds, a Lungo is more “highly extracted.” It will be thinner in body than a standard espresso and will often have more bitter, smoky, or toasted notes. While less common in specialty cafes (where we prefer the sweetness of a shorter shot), the Lungo is popular in Europe as a “longer” sipping coffee that still has the punch of an espresso.
Article 137: The “Refractometer” and Brew Charts
(Category: Coffee Science | Word Count: ~320)
To move from a “good” barista to a “master” barista, you must understand the Brew Chart. This is a graph that plots Strength (TDS) against Extraction Yield.
The Coordinates: - Strength (Vertical Axis): How “concentrated” the coffee is.
- Extraction (Horizontal Axis): How much of the bean’s mass you actually dissolved.
The “Ideal” Zone:
According to the Specialty Coffee Association, the “sweet spot” is typically between 18\% – 22\% Extraction and 1.15\% – 1.45\% TDS. - If your coffee is in the bottom-left corner, it is Weak and Under-extracted (sour/thin).
- If it is in the top-right corner, it is Strong and Over-extracted (bitter/muddy).
By using a digital refractometer to measure your TDS, you can plot your brew on this chart and know exactly how to adjust your grind or ratio to reach the “Ideal” zone.
Article 138: Why We Use “Micro-Holes” in Filter Paper
(Category: Brewing Methods | Word Count: ~200)
Not all paper filters are the same. If you look at a V60 or Chemex filter under a microscope, you will see a network of tiny cellulose fibers.
The Function:
These fibers create a “tortuous path.” Water can pass through, but large coffee particles and oils are trapped. - Chemex filters are very thick, removing almost all oils and producing the “clearest” cup.
- V60 filters are thinner, allowing a few more oils through for a slightly heavier body.
The “Paper” Taste:
Because they are made of wood pulp, paper filters can add a “cardboard” taste to your coffee. This is why it is essential to rinse your filter with hot water before adding the coffee grounds. This washes away the loose paper fibers and warms up your brewer at the same time.
Article 139: The “Double-Walled” Glass Advantage
(Category: Barista Skills | Word Count: ~180)
In high-end specialty cafes, drinks are often served in double-walled glass cups. This isn’t just because they look beautiful (allowing you to see the layers of a latte); it’s about Temperature Retention.
The layer of air trapped between the two glass walls acts as an insulator. - Keep it Hot: It prevents the heat from the coffee from escaping into the cold room air.
- Protect the Hand: It keeps the outside of the glass cool to the touch, so the customer doesn’t need a handle or a sleeve.
For a barista, these glasses are great for showing off “tiger-striped” espresso or the perfect separation in a Macchiato.
Article 140: Coffee Economics: The “C-Price” vs. Specialty
(Category: Coffee Business | Word Count: ~340)
Most of the world’s coffee is traded as a commodity on the New York Stock Exchange. This is known as the “C-Price.”
The Problem with the C-Price:
The C-Price is based on supply and demand, not on the quality of the coffee or the cost of production. If there is a massive harvest in Brazil, the price drops for everyone, even for a farmer in Kenya who grew incredibly high-quality beans. Often, the C-Price falls below the actual cost of farming, leaving farmers in poverty.
The Specialty Solution:
The specialty coffee industry operates on a different model. Roasters and buyers pay Direct Trade premiums. Instead of following the stock market, they pay a price based on the Cupping Score.
In Kenya, because our coffee is so high-quality, it often fetches prices 2\text{ to }4 times higher than the C-Price. This is why education is so important—when we teach baristas and farmers how to improve quality, we are directly helping them escape the trap of the commodity market.