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Four sample roasters go head-to-head on the same coffee, and only a blind cupping decides the winner. Ingo lines up the Ikawa, the Roest L200 Ultra, the Kaffelogic Nano7 and the Nucleus LINK, roasts one washed Colombia on each machine using nothing but its out-of-the-box profile, then hands the cups to two people whose palates you can trust: Sierra Yeo, reigning Swiss Brewers Cup Champion and Q Grader, and her guest Catherine Queiroz, Vice Champion of the World Cup Tasters Championship, Q Grader and Coffee Quality & Education Manager at Neumann Kaffee Gruppe.
Before the tasting starts, Ingo walks through how each machine actually works: the sensor placement, the roast chamber design and the batch sizes, ranging from 50 grams up to 200 grams depending on the roaster. Then it is a fully blind triangle cupping through the hot, warm and cool stages, with Sierra and Catherine describing every shift in acidity, sweetness and body as the cups cool down.
The result makes a strong case for value in specialty coffee roasting: the Nucleus LINK, which shares its core hardware with the considerably more affordable Kaffelogic Nano7, ends up beating the significantly pricier Roest L200 Ultra and Ikawa in this blind test. It is a good reminder that a roasting profile can matter just as much as the price tag on the machine.
The coffee used throughout is a washed Colombia San Sebastián, a versatile, people-pleasing cup with notes of green apple, citrus and caramel:
All four machines featured in this episode are available at Roast Rebels, Europe's platform for specialty coffee roasting equipment, green coffee and roasting education, with service centers in Germany and Switzerland and free EU shipping:
Kaffelogic Nano7:
Nucleus LINK:
Roest:
Want to learn how to get the most out of a Kaffelogic Nano7 at home? The Roast Rebels Academy course Start Coffee Roasting with the Kaffelogic Nano 7 covers 7 chapters and 24 videos in more than 3.5 hours, and comes free with a Kaffelogic Nano 7e purchased at Roast Rebels:
Follow Sierra Yeo on Instagram:
Follow Catherine Queiroz on Instagram:
Roast Rebels shop:
Roast Rebels Academy:
Timestamps:00:00 Intro: 4 sample roasters, 1 coffee00:22 Meet Sierra Yeo and Catherine Queiroz02:27 The machines: Ikawa, Roest, Kaffelogic Nano7 and Nucleus LINK05:21 Batch sizes compared: 50g to 200g06:39 How the Nucleus LINK works08:24 Roasting profiles explained09:21 Roasting the washed Colombia San Sebastián10:20 Sample 1: Ikawa11:22 Sample 2: Roest12:16 Sample 3 and 4: Kaffelogic Nano7 and Nucleus LINK14:43 Setting up the blind cupping15:53 Fragrance and aroma evaluation19:48 Hot stage tasting22:41 Warm stage tasting26:22 Cool stage and final scoring33:28 Reveal: 4th place – Ikawa34:20 Reveal: 3rd place – Kaffelogic Nano734:58 Reveal: 2nd place – Roest L200 Ultra35:07 Reveal: 1st place and winner – Nucleus LINK35:41 About the coffee: Colombia San Sebastián36:28 Follow Sierra and Catherine
Fresh back from Brussels: Sierra just competed at the World Brewers Cup 2026, and in this episode she sits down with Ingo to watch her own routine together — pausing along the way to unpack the details behind every pour.
From a brand-new vacuum degassing tool to a strict 10-minute clock that punishes every second over the limit, this is a behind-the-scenes look at what it actually takes to compete on coffee's biggest stage.In this conversation:🔥 Sierra's full World Brewers Cup performance, rewatched and broken down together🔥 How the score sheet works: bottom boxes, accuracy, and quality scoring explained🔥 A massive European heat wave and how it forced last-minute changes to coffee storage🔥 TIMEMORE's new vacuum tool, built to hit the "Goldilocks zone" between CO2 and oxidation🔥 Two kettles, two pour styles — why Sierra switches mid-routine🔥 What sensory judges, shadow judges, and head judges are each actually scoring🔥 Brewing three coffees in parallel under serious time pressure🔥 The dripper, booster, and server setup behind her cup🔥 A fresh 2026 harvest natural Geisha from Mt. Totumas, Panama🔥 Why a strong team behind the scenes makes or breaks a competition run🔥 Sierra's honest answer: should you compete in a Brewers Cup yourself?
Sierra represented Switzerland at the World Brewers Cup 2026 after winning the Swiss Brewers Cup. 46 countries competed this year. Competitors get 10 minutes to brew 3 coffees, losing 0.5 points for every second over — Sierra finished at 9 minutes 44 seconds, in a year so tight that 6th and 7th place ended up tied. Judges score across 6 attributes: aroma, flavor, acidity, sweetness, aftertaste, and mouthfeel. A new grinder rule this year limited the entire grind-to-brew window to 18 minutes total.
☕ About Roast RebelsRoast Rebels is Europe's go-to platform for specialty coffee roasting — small-scale roasting machines, high-quality green coffee, and courses for home roasters and professionals. Service centers in Germany and Switzerland, free shipping across the EU.
Sierra, featured in this episode, is Roast Rebels' content manager and green coffee buyer, and the 2026 Swiss Brewers Cup Champion.Shop: https://roastrebels.com/en
Academy: https://academy.roastrebels.com
You roast the same coffee, same profile — and it tastes completely different. The culprit is often hiding in your green coffee beans: moisture content and water activity. In this episode, Ingo from Roast Rebels breaks down what these two parameters mean, why they matter for green coffee quality and food safety, and how they directly shape your roast.
What you'll learn:
▸ Moisture content should sit between 10–12%. Below 8–9%: quality risk (hay, baked notes, fast aging). Above 12–13%: health risk from mold and bacteria.
▸ Water activity measures how freely water is bound in the bean (scale 0–1). SCA defines specialty coffee as below 0.7. Best practice: 0.5–0.6. Above 0.78: high microbial risk.
▸ Higher moisture = more energy needed in the drying phase. Lower moisture = faster drying, more careful heat management required.
▸ Proper packaging (GrainPro or Ecotact inside burlap) protects both parameters during storage and transport.
▸ Water activity has been underused in roasting due to expensive equipment — affordable tools are now changing this fast.
▸ Roast Rebels measures moisture content, density, and water activity on every green coffee delivery. Coffee at 13.5% moisture has been rejected.
Links & Resources
Green Coffee – A Guide for Roasters and Buyers
Measuring Devices at Roast Rebels
Roast Rebels Academy – Online Courses for Home & Pro Roasters
Roast Rebels Shop
About Roast Rebels
Roast Rebels is Europe's go-to platform for specialty coffee roasting. We sell small-scale roasting machines — including the Kaffelogic Nano 7e, Aillio Bullet, Gene Café, Behmor, and Nucleus LINK — alongside a curated selection of high-quality green coffees. Service centers in Germany and Switzerland. Free shipping across the EU.
The Roast Rebels Academy (academy.roastrebels.com) offers in-depth courses for home roasters and professionals, including the Aillio Bullet Masterclass: 11 chapters, 30 videos, 4+ hours of content (€249, free with hardware purchase from Roast Rebels).
Want to learn how to roast coffee but have no idea where to start? In this episode you get a structured overview of all learning paths – from in-person courses and online learning to books, coaching and learning by doing. And you'll find out what you should actually focus on first – the answer surprises most people.
What's covered in this episode:
ROAST REBELS COURSES & ACADEMY
In-Person Course Zurich – Coffee Roasting WorkshopDuration: approx. 4.5 hours. Content: green coffee fundamentals, roasting 4 different coffees, roasting theory, cupping, create and take home your own roast. Open to beginners and experienced home roasters. Usually in German; English documentation available on request; English courses 1–2x per year. Participants regularly travel from across Europe to attend.https://roastrebels.com/en/courses-events/
Roast Rebels Online Academy – available worldwideMachine-specific courses for Kaffelogic Nano 7e and Aillio Bullet. Covers: machine operation, green coffee selection, roasting theory, practical roasting exercises. Self-paced, available anytime. Included when purchasing selected machines from Roast Rebels.https://academy.roastrebels.com/courses
Roast Rebels ships machines and green coffee across Europe and offers online courses to roasters worldwide.
LINKS
Green coffee beans (EU shipping, free from €150): https://roastrebels.com/en/green-coffee/Books (Scott Rao, Rob Hoos, Book of Roast): https://roastrebels.com/en/books/Kaffelogic Nano 7e: https://roastrebels.com/en/kaffelogic-nano-7e/
ABOUT THE CONTENT
Coffee roasting is less complex than most people think – if you approach it in the right order.
Learning paths covered: in-person courses (incl. Roast Rebels Zurich, ~4.5h, English on request), Roast Rebels Online Academy (worldwide, machine-specific), YouTube, blogs, forums, books (Scott Rao, Rob Hoos, Book of Roast), coaching (Rob Hoos, Scott Rao, Morten Münchow / CoffeeMind, Nikolai Fürst, Gloria Pedrosa), learning by doing with Kaffelogic Nano 7e or Nucleus LINK.
ABOUT ROAST REBELS
Roast Rebels is your partner for specialty coffee roasting. From the best hardware like the Kaffelogic Nano 7 to high-quality green beans and expert-led courses – we help you roast coffee you'll love.Website: https://roastrebels.com/en
Rob Hoos is back! Three years after our first viral interview (50k+ views), we dive deep into his latest research on airflow, cultivars, and roasting physics. 👉 Rob's new book "Cultivar": https://roastrebels.com/en/cultivar-a-practical-guide-for-coffee-roasters/In this exclusive deep dive, Ingo talks to world-renowned roasting consultant and author Rob Hoos. Rob shares his most significant breakthroughs from the last three years of research and consulting.We’re breaking down the myths: Why is the genetic variety (cultivar) often more important than terroir? How does airflow impact the actual weight loss curve and flavor development? And how do you roast a Maragogype to bring out those elusive tropical fruit notes?Whether you are a home roaster or running a commercial roastery, this interview will fundamentally change how you approach your roast profiles.00:00 – Welcome back, Rob Hoos: A 3-year followup 00:32 – Who is Rob Hoos? Consulting, Books & SCA 01:43 – The biggest learnings from the last 3 years 02:15 – Focus on Cultivars: Beyond field blends 03:54 – Airflow Revolution: Impact on flavor & weight loss 05:45 – Convection vs. Conduction in drum roasting 07:22 – Why the deep dive into Coffee Cultivars? 09:50 – Terroir vs. Genetics: How understanding has shifted 11:43 – The Maragogype Revelation: Tropical fruit from PNG 16:20 – The "Cultivar Project": 8 years of research 19:35 – Coffee Science: The evolution since the 2000s 22:20 – Altitude & Terroir: Correlation vs. Causation 24:44 – The Galapagos Case: High density at low altitude 30:08 – Genetic Purity: Cross-pollination and seed banks 33:55 – The mystery of "SL-R": A hidden Castillo story 37:40 – The 4 Genetic Groups: Typica, Bourbon, Ethiopia, Hybrid 40:40 – Roasting Strategy: Why "Fast" isn’t always best 46:15 – Moisture & Density: Applying heat energy correctly 51:40 – Why wet coffee can "run away" from you 54:20 – The "Perfect Recipe": Roasting for maximum fruitiness 57:34 – Rob Hoos’ Online Community & Mentorship 59:30 – Conclusion: Final thoughts on the coffee industry► Find Rob Hoos’ new book "Cultivar" here: https://roastrebels.com/en/cultivar-a-practical-guide-for-coffee-roasters/► Visit Rob Hoos online: https://www.hoos.coffee ► Follow Rob on Instagram: https://www.instagram.com/robhoos/► Join the Roast Rebels Movement: https://roastrebels.com▬ About this channel ▬▬▬▬▬▬▬▬▬▬▬▬At Roast Rebels, our mission is to make coffee roasting easy. On the one hand we offer the most proven small scale roasting machines and high quality green coffees, on the other hand we want to support people who roast coffee with tips, knowledge, roasting profiles and tutorials to achieve good roasting results quickly. You'll find lots of information and roasting profiles on our website, as well as here on the YouTube channel. #homeroasting #coffeeroasting▬ More Information ▬▬▬▬▬▬▬▬▬▬▬▬You will find a lot more information as well on our website: https://roastrebels.com/en▬ Social Media ▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬►Facebook: https://www.facebook.com/roastrebels/►Instagram: https://www.instagram.com/roastrebels/►Newsletter: https://eepurl.com/dxHgML►Podcast (Roasting coffee - made easy): https://anchor.fm/roasting-coffee►Onlineshop for European coffee roasters: https://roastrebels.com/en/►Onlineshop for coffee roasters in Switzerland: https://roastrebels.com/ch/en/#CoffeeRoasting #RobHoos #RoastRebels #SpecialtyCoffee #RoastProfile #CoffeeScience #Cultivars #HomeRoasting
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