This batch explores the “Golden Ratio,” coffee’s chemical compounds, and the specific impact of the Nairobi Coffee Exchange.
Article 81: The “Golden Ratio” of Coffee Brewing
(Category: Brewing Methods | Word Count: ~280)
If you are struggling to make a balanced cup of coffee at home, your ratio is likely off. The “Golden Ratio” is the industry-standard starting point for filter coffee: 1:17.
This means for every 1\text{ gram} of coffee, you use 17\text{ grams} of water.
Why it works:
- Balance: At 1:17, the water has enough “solvent capacity” to pull out the sugars and acids without over-extracting the bitter tannins.
- Strength: It produces a Total Dissolved Solids (TDS) level of about 1.25\%, which most people perceive as a “perfect” strength—neither too weak nor too intense.
How to Calculate:
If you have a mug that holds 300\text{ ml} of water, divide 300 by 17. You need approximately 17.6\text{ g} of coffee. If you prefer a stronger, heavier cup, you can try a 1:15 ratio. If you want a light, tea-like Kenyan pour-over, try 1:18.
Article 82: Understanding Caffeine: The Plant’s Defense Mechanism
(Category: Coffee Science | Word Count: ~310)
We drink caffeine for the energy boost, but the coffee plant produces it for a much more practical reason: survival. Caffeine is a natural pesticide and herbicide.
- Insect Repellent:
Caffeine is toxic to many insects. If a pest tries to eat the leaves or cherries of a coffee plant, the caffeine paralyzes or kills them. Interestingly, in very small doses (like those found in nectar), caffeine actually helps honeybees remember the plant, encouraging them to return for pollination. - Weed Killer:
When coffee leaves fall to the ground and decompose, they release caffeine into the soil. This inhibits the germination of other competing plants, ensuring the coffee tree has more access to water and nutrients. - Altitude and Caffeine:
This is why Robusta (grown at low altitudes with many pests) has twice the caffeine of Arabica (grown at high altitudes with fewer pests). The plant simply doesn’t need to produce as much “defense” in the cool, bug-free mountains of Nyeri or Meru.
Article 83: The Role of the Nairobi Coffee Exchange (NCE)
(Category: Coffee Export/Business | Word Count: ~350)
The Nairobi Coffee Exchange is the heart of Kenya’s coffee economy. Established in the 1930s, it is a central auction system where the country’s high-quality beans are sold to the international market.
How it Works:
Each week, samples from different factories (washing stations) and estates are sent to the Exchange. Registered buyers—representing roasters from Europe, the US, and Asia—spend days cupping these samples. On auction day, bidding happens in a fast-paced environment.
Transparency and Quality:
The NCE is one of the reasons Kenyan coffee remains high-quality. Because it is a transparent auction, the best-tasting coffee gets the highest bids. This creates a direct incentive for farmers and cooperatives to maintain strict quality control during harvesting and processing.
Direct Settlement System (DSS):
A recent improvement to the exchange is the DSS, which ensures that farmers are paid more quickly and directly after a sale is made. For students at the Kenya Coffee School, understanding how the NCE operates is essential for anyone looking to enter the world of coffee trading or exporting.
Article 84: What is “Blond” Roast?
(Category: Roasting Knowledge | Word Count: ~240)
In recent years, “Blond” roast has become a popular term, popularized by major chains, but it is essentially a rebranding of a Light Roast.
The Profile:
A blond roast is pulled out of the roaster immediately after “First Crack” begins. The beans are light brown and have no visible oil on the surface.
The Flavor:
- Acidity: It is very high in acidity and “brightness.”
- Caffeine: Contrary to popular belief, blond roasts have slightly more caffeine by volume because the beans are denser and haven’t lost as much mass to heat.
- Notes: You will taste more of the “origin” characteristics—lemon, grass, flowers, and toasted grain.
While blond roasts can be sour if not brewed correctly, they offer the most honest representation of a bean’s quality. If a bean has a defect, you will taste it in a blond roast; you can’t hide anything behind a light profile.
Article 85: The Physics of the “Vortex” in Milk Steaming
(Category: Barista Skills | Word Count: ~210)
When steaming milk, you are aiming for a “vortex”—a rapidly spinning whirlpool of milk. This isn’t just for looks; it is essential for texture.
Once you have finished “stretching” the milk (adding air), you must submerge the wand slightly and tilt the pitcher to start the spin. The vortex acts like a blender. It takes the large bubbles you created on the surface and pulls them down into the liquid, breaking them into microscopic bubbles.
The Goal:
Without a strong vortex, you will end up with “dry” foam on top and hot, watery milk underneath. With a vortex, you get microfoam: a uniform, glossy liquid that looks like melted marshmallows and is perfect for pouring latte art.
Article 86: Why Coffee “Sweats” in the Bag
(Category: Coffee Storage | Word Count: ~190)
If you see moisture or “sweat” inside your bag of coffee, it is usually a sign of a temperature problem. Coffee beans contain a small amount of residual moisture (about 10\%-12\% green, and much less after roasting).
If coffee is stored in a warm place and then suddenly cools down, that moisture condenses. This is dangerous because moisture triggers staling. It causes the oils to turn rancid and can even lead to mold growth.
The Fix:
Keep your coffee in a “stable” environment. Avoid the top of the fridge (which gets warm from the motor) or the cupboard next to the oven. A cool, dark pantry is the best place to prevent “sweating” and keep your beans crisp and aromatic.
Article 87: Introduction to the Siphon (Vacuum) Brewer
(Category: Brewing Methods | Word Count: ~320)
The Siphon is perhaps the most theatrical way to brew coffee. Looking like a laboratory experiment, it uses vapor pressure and vacuum force to produce a cup that combines the clarity of a pour-over with the body of a French Press.
How it Works: - Heating: Water is heated in the bottom globe. As it turns to vapor, it creates pressure that pushes the water up into the top chamber where the grounds sit.
- Immersion: The coffee steeps in the top chamber in a state of full immersion.
- The Vacuum: Once the heat source is removed, the air in the bottom globe cools and contracts, creating a vacuum that “sucks” the coffee back down through a filter.
The Flavor:
Because siphons usually use a cloth filter and high temperatures, the resulting coffee is incredibly hot and very clean, but with a more rounded, silkier mouthfeel than a paper-filtered V60. It is a favorite for showcasing the “winy” acidity of high-end Kenyan coffees in a premium café setting.
Article 88: Why “Pre-Heating” Your Equipment Matters
(Category: Brewing Methods | Word Count: ~200)
Temperature stability is the secret to professional-tasting coffee. One of the biggest mistakes home brewers make is pouring hot water into a cold ceramic V60 or a cold glass Chemex.
The Thermal Sink:
Ceramic and glass act as “heat sinks.” If your water is at 95^\circ\text{C}, but your brewer is at room temperature (20^\circ\text{C}), the brewer will instantly absorb the heat from the water. Your actual brewing temperature might drop to 80^\circ\text{C}, leading to a sour, under-extracted cup.
The Solution:
Always “rinse” your brewer and your server with hot water before adding the coffee grounds. This warms up the equipment and ensures that the water stays at the correct temperature for the entire duration of the brew.
Article 89: Understanding “Milling” and “Hulling”
(Category: Coffee Education | Word Count: ~270)
After coffee is dried on the farm, it is still covered in a protective layer called Parchment. Before it can be exported, it must go through a “Dry Mill.”
The Process: - Hulling: Machines use friction to rub the parchment skin off the green beans.
- Polishing: An optional step that removes any remaining “silver skin,” making the beans look shiny and clean.
- Grading: The beans are passed over vibrating screens to separate them by size (AA, AB, etc.).
- Color Sorting: High-tech “optical sorters” use cameras to identify and blow away discolored or defective beans that a human eye might miss.
Milling is the final quality-control gate. A good mill can take a “standard” lot of coffee and turn it into a “premium” lot simply by removing the defects and sorting the sizes perfectly.
Article 90: The Ethics of “Free Coffee” in Barista Training
(Category: Coffee Business | Word Count: ~310)
In many barista schools, students are encouraged to make as many coffees as possible. However, at schools like Barista Mtaani, there is a focus on sustainability and waste awareness.
The Cost of Learning:
Every time a student pulls a bad shot or spoils a pitcher of milk, it costs the school money. But more importantly, it represents the hard work of a farmer in Kericho or Nyeri.
The Mindset:
A professional barista respects their ingredients. - Milk: Only pour exactly what you need for the cup size.
- Coffee: If you are practicing latte art, you don’t always need a fresh espresso; you can practice the “pour” using water and a drop of soap, or reuse old coffee “crema” created from recycled grounds.
Training with a focus on “Zero Waste” doesn’t just save money; it prepares baristas for the reality of working in a high-end café where efficiency is a key performance indicator.
That’s 90 articles! You’re nearly 40% of the way there.