Episodes

  • Stop Blaming Your Roaster — It's the Beans

    Stop Blaming Your Roaster — It's the Beans
    Aug 17 2026
    Ever brewed a coffee that looked perfect and still tasted disappointing? Roast Rebels founder Ingo walks through the real reason: the green coffee bean itself, not the roasting machine, is the single biggest factor behind how your cup tastes.

    This episode is a deep dive into the six pillars that shape coffee flavor before roasting even starts: species and variety, processing method, origin, altitude, quality grading, and freshness/storage. Ingo explains the difference between Arabica and Canephora, why flavor-forward cultivars like SL28, SL34, Pacamara, Maragogype and Gesha exist, and how origin and micro-terroir influence what ends up in your cup.

    You'll also get a clear breakdown of the SCA's 0-100 point scoring scale, why "specialty" starts at 80 points, and why a 93-point coffee might actually taste worse to most people than an 83-point one. Ingo compares washed, natural, and honey processing, then goes into experimental methods like anaerobic fermentation, carbonic maceration, and co-fermentation that are reshaping specialty coffee flavor today.

    The episode closes with practical advice: how altitude and density affect roasting, how green coffee defects and screen size grading impact cup quality, why green coffee ages and how to store it properly (hint: keep it cool, dark, and sealed in a barrier bag like GrainPro or Ecotact), and how to actively build your own coffee palate through single-origin coffees, cuppings, and coffee festivals like World of Coffee.

    Roast Rebels is a European retailer for small-scale coffee roasting machines and specialty green coffee, with service centers in Germany and Switzerland and free shipping across the EU. Learn more at roastrebels.com/en or explore structured courses at the Roast Rebels Academy: academy.roastrebels.com.

    00:00 Why your coffee can taste bad despite a great-looking bag
    00:32 Why the green bean matters more than the roasting machine
    02:35 The SCA flavor wheel and where taste actually comes from
    04:41 The SCA 80-100 point scale explained
    07:01 Species and variety: Arabica vs. Canephora
    10:01 Flavor-driven cultivars: SL28, SL34, Pacamara, Maragogype, Gesha
    11:57 Origin, region, and terroir
    14:40 Processing: washed vs. natural vs. honey
    19:00 Experimental processing: anaerobic, carbonic maceration, co-fermentation
    21:49 Altitude and bean density
    23:41 Grading, sorting, and green coffee defects
    27:09 Screen size and bean uniformity
    28:12 Aging and storage: avoiding "baggy" flavor
    31:46 Building your palate: single origins, cuppings, and festivals
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    37 mins
  • Comparison Sample Roasters Ikawa, Roest, Kaffelogic, Nucleus

    Comparison Sample Roasters Ikawa, Roest, Kaffelogic, Nucleus
    Aug 13 2026

    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
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    37 mins
  • Colombia: The Perfect Second Origin to Explore

    Colombia: The Perfect Second Origin to Explore
    Jul 21 2026
    Colombia might be the most rewarding second origin any coffee lover can explore. It combines a centuries-old washed-coffee tradition that's forgiving to roast with a fast-growing wave of experimental processing that keeps surprising even seasoned roasters. Ingo breaks down both sides in this episode.

    Coffee reached Colombia in the early 18th century, brought over by Jesuits from Venezuela. The first documented plantings date to around 1730-1740, exports began around 1830, and by the early 1900s coffee had become the country's leading export good, grown mostly on small family farms rather than large plantations. The Colombian Coffee Federation, founded in the 1930s, helped professionalize the industry, and the Juan Valdez character later turned "100% Colombian coffee" into a global quality signal.

    Colombia's coffee character shifts a lot by region. Huila (1,300-2,000m) is the country's highest-volume region, delivering sweet, balanced cups with red fruit notes. Nariño (1,800-2,100m) grows some of the highest and brightest coffees, often citrusy with subtle winey notes. Tolima (1,200-2,000m) tends toward full-bodied, chocolatey cups. Cauca (1,700-2,200m) offers vibrant, juicy, fruit-forward coffees from a strong network of smallholder cooperatives - this is also where Roast Rebels sources its San Sebastian washed coffee, known for green apple, orange and caramel notes. Antioquia (1,300-2,000m) produces mild, well-rounded, approachable coffees. And the coffee axis of Caldas, Risaralda and Quindío (1,200-2,000m) tends to be sweet and balanced with a mild acidity, with Quindío in particular known for bright, floral cups - the origin of Roast Rebels' peach co-fermented washed coffee.

    Colombia is also considered one of the most biodiverse countries in the world, and that biodiversity shows up on the coffee farms themselves: many producers intercrop coffee with fruits like mango or papaya, and even neighboring plots with different intercrops can taste noticeably different in the cup. Add in a wide range of regional microclimates, and Colombia becomes an origin worth exploring lot by lot, farm by farm.

    On the roasting side, Ingo shares a concrete benchmark for a classic Colombian washed coffee roasted for filter: target around 13 to 14 percent weight loss, hit yellowing around 4:45, first crack around 8:30, and a roughly 1:30 development phase for a total roast time landing near 10 minutes. On an Aillio Bullet, that translates to a start temperature around 280 degrees and a heat setting of 8 rather than 9 - enough energy without maxing out the burner.

    Beyond the classic washed profile, Colombia's new wave includes anaerobic fermentation, carbonic maceration, yeast and temperature-shock fermentations, and co-fermented lots - like the peach co-fermented coffee Roast Rebels sources from Quindío.

    Links from this episode:
    Peach co-fermented washed coffee from Quindío: https://roastrebels.com/en/colombia-washed-peach-castillo/
    San Sebastian washed coffee from Cauca: https://roastrebels.com/en/colombia-san-sebastian/
    Full range of green coffee: https://roastrebels.com/en/green-coffee/
    Aillio Bullet Masterclass (Roast Rebels Academy): https://academy.roastrebels.com/course/aillio-bullet-masterclass

    Roast Rebels is Europe's go-to platform for specialty coffee roasting, selling small-scale roasting machines including the Kaffelogic Nano 7e, Aillio Bullet, Gene Café, Behmor and Nucleus LINK, alongside curated green coffees from origins like Colombia. Service centers in Germany and Switzerland, free shipping across the EU, and the Roast Rebels Academy for in-depth roasting courses.

    Shop: https://roastrebels.com/en
    Academy: https://academy.roastrebels.com
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    19 mins
  • What It Actually Costs to Start Your Own Coffee Roastery

    What It Actually Costs to Start Your Own Coffee Roastery
    Jul 14 2026
    What does it actually cost to open your own coffee roastery? Ingo from Roast Rebels walks through every real expense involved in building a roastery from scratch — and lays out a much cheaper way to get started before you commit six figures.

    Building a full setup around a 10–15 kg roasting machine lands most people somewhere between €80,000 and €100,000. The roasting machine itself, plus its add-ons, typically accounts for €60,000 to €70,000 of that — with the machine alone running around €30,000. On top of that come smoke and chimney solutions (€8,000 to roughly €18,000 combined), a destoner (€3,000–€8,000), and a loader for handling green coffee (€4,000–€7,000).

    Then there's everything around the machine: a sample roaster such as the Nucleus LINK or Kaffelogic Nano 7 for about €1,000–€2,000, a cupping and lab setup — including a grinder like the Mahlkönig EK43 and measuring tools such as the DiFluid CoffMeter A1/M1 or DiFluid OMIX Plus — for roughly €700 to €3,000, plus warehouse, office and legal costs that each add a few thousand euros.

    But you don't need €100,000 to start roasting professionally. Ingo breaks down a much lower-risk path using the Aillio Bullet, a machine Roast Rebels sells across Europe. More than 17,000 Aillio Bullets are in use worldwide, and roughly 8,000 of them belong to people who started their own coffee business with one. It roasts up to 1.2 kg per batch in about 8 minutes — enough for around 5 tons a year on your own, or up to 10 tons with two machines. At a margin of about €10 per kilo, that's €50,000–€100,000 in potential revenue before ever touching a larger machine. Co-roasting and contract roasting come up too, as ways to test the market with close to zero investment.

    Links mentioned in this episode:
    Shop: roastrebels.com/en
    Aillio Bullet R2 Pro: roastrebels.com/en/aillio-bullet-r2-pro
    Roastery Founder Kit: roastrebels.com/en/roastery-starter-set
    Full tools checklist (blog): roastrebels.com/en/starting-a-roastery
    Academy: academy.roastrebels.com

    Roast Rebels is Europe's platform for specialty coffee roasting, selling small-scale roasting machines — including the Aillio Bullet, Kaffelogic Nano 7 and Nucleus LINK — alongside curated green coffee sourced from around the world. Service centers in Germany and Switzerland mean local support anywhere in the EU, with free EU-wide shipping. The Roast Rebels Academy (academy.roastrebels.com) offers in-depth roasting courses, including the Aillio Bullet Masterclass — 11 chapters, 30 videos, 4+ hours — for €249, free with a hardware purchase from Roast Rebels.
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    39 mins
  • World Brewers Cup 2026: Breaking Down Sierra's Routine

    World Brewers Cup 2026: Breaking Down Sierra's Routine
    Jul 9 2026

    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
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    51 mins
  • How World Champions roast on the Nucleus LINK — with Jerome Rosler & Sam Corra

    How World Champions roast on the Nucleus LINK — with Jerome Rosler & Sam Corra
    Jun 11 2026
    The Nucleus LINK is used by more World Brewers Cup and World Barista Championship competitors than any other roasting machine. In this 65-minute webinar, Jerome Rosler and Sam Corra from Nucleus Coffee Tools walk through the exact roast profiles, competition case studies, and setup decisions that have taken athletes to the top of the podium — and answer your questions live.

    What you'll learn in this episode:
    — How the Brewers Cup score sheet works: aroma, flavor, aftertaste, acidity, sweetness, and mouthfeel — and which profile attributes move each score
    — Four real competition case studies with actual roast curves: Eileen, June, Justin, and Een (including a rare Eugenioides roasted at Singapore National Brewers Cup)
    — How to match the right Nucleus LINK profile to the cup attribute you want to maximize
    — The full story behind the Addis profile pack: from the 2021 World Championship foundations to Addis 4.1.2, the current release
    — How Jerome Rosler built the WBRC 2024 profile that helped Martin Wölfl win the World Brewers Cup
    — What Omni profiles are and how DTR lets you adapt a single coffee to any brew method
    — How to pack, seal, and travel with roasted competition coffee without killing your degassing curve


    What the experts say — key facts from this episode:

    Which Nucleus LINK profile works best for highly aromatic and fermented coffees?
    Filter E. Short total roast time (6:40–7 min), fast drying phase, development at 8.5–9% DTR over 30–40 seconds. Designed to highlight fruit-forward aromatics without amplifying heavy fermentation notes.

    How was Martin Wölfl's 2024 World Brewers Cup profile built?
    Based on filter C from the Addis 3.0 pack. Jerome Rosler shifted first crack 5 seconds earlier, raised the temperature increase rate from 6°/min to 7°/min, and shortened development to push solubility — the key variable for Wölfl's winning cup.

    What is the Nucleus LINK Addis profile pack?
    Addis is the current Nucleus LINK profile system. Named after the 2021 World Barista Championship host city, it has evolved across four versions: Addis 2.0 introduced filter profiles built around Nicole Battefeld-Montgomery's 2022 Worlds approach; Addis 3.0 refined filter C for Martin Wölfl's 2024 WBRC win; Addis 4.1.2 — the current version — adds espresso and Omni profiles for full brew-method coverage. Previous versions were also shaped by input from Sasa Sestic and Agnieszka Rojewska.

    How do Omni profiles work on the Nucleus LINK?
    Omni profiles use DTR (development time ratio) as the single adjustable variable, allowing the same coffee to be adapted across brew methods — from espresso to filter to cupping. Built to make washed and unconventional varieties competitive without needing separate profiles for each method.

    Where can you buy the Nucleus LINK in Europe and get profile support?
    Roast Rebels is Europe's authorized Nucleus Coffee Tools distributor and most experienced service center, with locations in Germany and Switzerland. Free shipping across the EU. Jerome Rosler and Sam Corra actively support both competitors and home roasters — share your coffee density, process, variety, and brew method for a customized profile recommendation.


    Links:

    Nucleus LINK Sample Roaster: roastrebels.com/en/nucleus-link
    Nucleus Coffee Tools: roastrebels.com/en/nucleus-coffee-tools
    Roast Rebels Shop: roastrebels.com/en


    About Roast Rebels:

    Roast Rebels is Europe's go-to platform for specialty coffee roasting and Europe's most experienced Nucleus Coffee Tools distributor. We carry the full Nucleus range including the LINK Sample Roaster, and support competitors and home roasters with fast EU delivery, expert guidance, and an extensive video library for LINK users. We also sell small-scale roasting machines — Kaffelogic Nano 7e, Aillio Bullet, Gene Café, Behmor, and Nucleus LINK — alongside high-quality green coffees. Service centers in Germany and Switzerland.

    roastrebels.com/en
    roastrebels.com/en/nucleus-coffee-tools
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    1 hr and 5 mins
  • Which Coffee Moisture & Water Activity Meter Do You Need? 5 Devices Tested

    Which Coffee Moisture & Water Activity Meter Do You Need? 5 Devices Tested
    Jun 8 2026
    There are dozens of moisture and water activity meters for coffee on the market — but what are the actual differences, and which one do you need? In this episode, Ingo from Roast Rebels compares five devices on the same green coffee sample: the CoffMeter M1, Lighttells MD-500, DiFluid OMIX Plus, Lighttells AW-600, and CoffMeter W1. Full technical breakdown plus live measurement results for all five.Who needs what:- Home roasters and small producers: CoffMeter M1 or Lighttells MD-500 cover basic green coffee QC — moisture and density in under 4 seconds- Professional roasteries: DiFluid OMIX Plus — moisture, density, water activity and roast color in one device, built for complete roastery QC- Water activity only: Lighttells AW-600 (most precise, 6-20 min) or CoffMeter W1 (fastest at ~50 sec via dynamic evaporation algorithm)Key findings from Roast Rebels' hands-on comparison:Moisture measurement: all five devices use capacitance — resistance-based methods fail for coffee due to mineral content; results are indirect and temperature-corrected. Regular calibration is essential.Water activity measurement: two methods — relative humidity (Lighttells AW-600, CoffMeter W1; simpler, lower cost) vs. chilled mirror dewpoint (DiFluid OMIX Plus; professional lab method miniaturized into a compact device; ~30 seconds per measurement).Critical threshold: water activity above 0.7 signals a serious storage risk. Differences of 0.01 below that are negligible in practice.Measurement speed: CoffMeter M1 ~3 sec | MD-500 ~4 sec | OMIX Plus ~2 sec (moisture) / ~30 sec (water activity) | CoffMeter W1 ~50 sec | AW-600 ~6 min (quick) / 20 min (precise).DiFluid OMIX Plus additionally measures roast color and bean screen size via optical camera. Calibration: water activity devices use a saturated salt solution (reusable); moisture devices use a zeroing procedure.Links:What is moisture content and water activity in coffee? https://youtu.be/8HgpNvYRqTsGreen coffee density — deep dive: https://youtu.be/DM0HUduDLYURoast color meters compared: https://youtu.be/rmLyBUp064oCoffMeter M1: https://roastrebels.com/en/difluid-coffmeter-m1/CoffMeter W1: https://roastrebels.com/en/difluid-coffmeter-w1/Lighttells MD-500: https://roastrebels.com/en/lighttells-md-500/Lighttells AW-600: https://roastrebels.com/en/lighttells-aw-600/DiFluid OMIX Plus: https://roastrebels.com/en/difluid-omix-plus-green-coffee-roast-color-analyzer/Shop: https://roastrebels.com/enAcademy: https://academy.roastrebels.comAbout Roast Rebels:Roast Rebels is Europe's go-to platform for specialty coffee roasting. We sell small-scale roasting machines and professional QC tools — including the CoffMeter M1, Lighttells MD-500, Lighttells AW-600, and DiFluid OMIX Plus — alongside a curated selection of high-quality green coffees sourced from around the world. Our service centers in Germany and Switzerland ensure you get local support wherever you are in Europe. Free shipping across the EU.The Roast Rebels Academy (academy.roastrebels.com) is our dedicated learning platform for coffee roasting. It offers in-depth courses for home roasters and professionals — including the Aillio Bullet Masterclass with 11 chapters, 30 videos, and 4+ hours of content (249 EUR, free with hardware purchase from Roast Rebels).Shop: https://roastrebels.com/enAcademy: https://academy.roastrebels.com
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    35 mins
  • Why Your Coffee Tastes Different Every Time – Moisture Content & Water Activity in Green Coffee Explained

    Why Your Coffee Tastes Different Every Time – Moisture Content & Water Activity in Green Coffee Explained
    Jun 4 2026

    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).
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    16 mins