A buyer in Manila once messaged us three days after his roaster cleared customs: “The machine works, but every batch tastes different. What am I doing wrong?” Nothing was wrong with the machine. He was roasting by clock and colour, with no coffee roast profile to repeat. That is the single most common gap we see between a roastery that survives its first year and one that does not — and it has almost nothing to do with which roaster you bought.
This guide explains how a roast profile is actually built on a commercial drum roaster: charge temperature, turning point, the three phases, rate of rise, and development time ratio. We build roasters at our factory from 1 kg to 300 kg, and we set a first working profile with every machine we ship, so the numbers below are the ones our engineers hand over on commissioning day — not textbook theory.
What a Roast Profile Actually Is
A roast profile is a recorded curve of bean temperature over time, plus the control inputs (gas or element power, airflow, drum speed) that produced it. It is not a recipe you can copy from the internet. Two roasters with identical rated capacity can read 8–12 °C apart at the same real bean temperature, purely because of probe diameter and how deep the probe sits in the bean mass. That is why a profile is portable within your machine and rarely portable between machines — a point we cover in more detail in our guide to reading a coffee roaster spec sheet.
What is transferable is the shape: a declining rate of rise, a defined first crack, and a controlled development window. Get the shape right on your machine and the numbers become yours.
The Five Reference Points Every Profile Needs
| Reference point | Typical drum roaster range | What it controls |
|---|---|---|
| Charge temperature | 180–210 °C bean probe | Energy available in the first two minutes |
| Turning point (TP) | 85–105 °C, at 60–120 s | Confirms your charge weight and preheat match |
| Dry end / yellowing | 150–160 °C, 40–50% of total time | Moisture removal, even heat penetration |
| First crack (FC) | 195–205 °C | Start of the development window |
| Drop temperature | 203–218 °C depending on roast level | Final acidity/body balance |
Total batch time on a commercial drum machine usually lands between 9 and 14 minutes. Faster than 8 minutes on a gas drum roaster and you are usually scorching the surface; slower than 16 and you are baking out sweetness.
Phase 1: Drying (Charge to ~150 °C)
Green coffee arrives at roughly 9–12% moisture. Until that water is gone, the beans cannot brown — you are essentially running a dryer. Two rules matter here:
- Charge hot enough that TP is not late. If your turning point arrives after 2 minutes, your preheat was too low for the batch weight, and every phase downstream gets compressed.
- Do not chase the curve with the gas valve. On a drum machine the steel mass responds slowly. A gas change made now shows up in the bean temperature 45–90 seconds later. New roasters over-correct, then over-correct back, and end up with a saw-tooth profile that never repeats.
Drying should take about 40–50% of total roast time. Much shorter and the outside of the bean runs ahead of the inside; much longer and you flatten the cup.
Phase 2: Maillard / Browning (150 °C to First Crack)
This is where sugars and amino acids build the flavour compounds you actually sell. The practical control here is airflow, not gas. Opening the damper increases convective heat transfer and carries off chaff; closing it holds heat in the drum but risks smoke re-depositing on the beans. Our SD and YS machines both let you set damper positions per phase, and on YS Series roasters with Siemens PLC control those positions are stored with the profile so the next operator does not have to guess.
A workable starting point on most batch sizes: hold the damper at 40–50% through drying, then step to 60–70% at the start of browning, then to 80–100% about 30 seconds before first crack.
Phase 3: Development (First Crack to Drop)
Development time ratio (DTR) is the number professionals argue about and beginners ignore:
DTR = (time from first crack to drop) ÷ (total roast time)
Filter/light: 15–18% | Balanced/omni: 18–22% | Espresso/dark: 22–26%
On a 12-minute roast, a 20% DTR means dropping 2 minutes 24 seconds after first crack starts. Two failure modes dominate this phase:
| Symptom on the curve | Cause | Fix on the next batch |
|---|---|---|
| RoR crash — rate of rise drops sharply at first crack | Endothermic moment of FC with too little stored energy; often too little gas from mid-browning | Raise gas slightly 60–90 s before expected FC, not after |
| RoR flick — curve rises again after the crash | Over-correcting the crash with a late gas increase | Make the pre-FC adjustment smaller and earlier; leave gas alone after FC |
| Flat, stalled curve | Batch too large for the burner, or damper wide open bleeding heat | Reduce charge weight or close the damper one step — see our batch size guide |
Recording the Profile: Artisan and PLC Storage
You cannot repeat what you did not record. Roughly one in ten of our support conversations is about profile logging, and the most common one is a buyer writing something like “Artisan says Yoshan DY 3kg, but Bluetooth will not connect.” The short answer is that the DY series logs over a wired USB adapter rather than Bluetooth pairing — the full setup, port settings and device list are in our guide to connecting a coffee roaster to Artisan.
Two levels of profile control exist on our machines:
- Log and replicate manually (DY series, SD series with analogue control): Artisan records the curve, the operator reproduces the control moves. Cheap, flexible, dependent on operator skill.
- Store and recall automatically (YS Series with Siemens S7-1200 PLC): the profile including gas and damper steps is stored on the panel and replayed batch after batch. This is what buyers with multiple shifts or high staff turnover need — the reasoning is set out in our article on Siemens PLC roaster control.
If you are roasting one origin for wholesale contracts, automatic recall pays for itself in rejected-batch savings within a year.
Building Your First Three Profiles
New machines need a break-in period before profiles stabilise — the drum, chaff cyclone and ducting all change how they hold heat over the first 20–30 hours. Do the seasoning roasts first (see commissioning and drum seasoning), then work like this:
- Batch 1 — benchmark. Charge at 195 °C, 70% of rated capacity, steady gas, damper mid. Record everything. Do not judge the cup; you are measuring your machine.
- Batch 2 — fix the phases. Adjust preheat so TP lands at 60–90 s and dry end at 45% of total time.
- Batch 3 — fix development. Keep everything up to first crack identical, change only the drop time to hit your target DTR. Cup batches 2 and 3 side by side.
Change one variable per batch. Roasters who change three things at once learn nothing from ten batches; roasters who change one thing learn something from every batch.
Frequently Asked Questions
What is a good coffee roast profile for a commercial drum roaster?
For most washed arabica on a gas drum machine: charge around 190–200 °C, turning point at 60–90 seconds, dry end near 150 °C at 45% of total time, first crack around 9 minutes, and drop at a development time ratio of 18–22% for a balanced roast. Treat these as a starting point and calibrate to your own probe readings.
Why does my rate of rise crash at first crack?
First crack is endothermic — the beans absorb energy to release moisture and CO₂. If the drum does not have stored heat going into it, bean temperature stalls. Add a small gas increase 60–90 seconds before first crack rather than reacting after the crash, which produces a flick.
Can I copy a roast profile from another roaster brand?
Only as a shape, not as numbers. Probe thickness, probe position and drum mass differ between machines, so the same real bean temperature can display several degrees apart. Copy the phase ratios and the DTR target, then rebuild the absolute temperatures on your own machine.
Do I need PLC control to get repeatable roasts?
No — skilled operators produce excellent repeatability on manual machines. PLC profile recall matters when repeatability must survive staff changes, multiple shifts, or wholesale contracts with a fixed flavour spec. Our DY and SD lines cover the first case; the YS line with Siemens PLC covers the second.
How many roasts before a new machine gives stable profiles?
Plan on 20–30 hours of running. Expect the first several batches after seasoning to run slightly differently as the drum, ducting and cyclone reach their normal thermal state. Log them anyway — that data is your baseline.
Get a Quote
Tell us your green coffee, target roast levels and weekly volume, and we will recommend a machine and send you a first working profile for it. Every roaster we ship is test-roasted at our factory and leaves with a commissioning profile and a video of your actual machine running. Full range: commercial coffee roasters 1 kg to 300 kg, including the SD Series and the PLC-controlled YS Series.
Use the enquiry form on our contact page for a full written quotation, or message us directly for a fast answer:
WhatsApp our engineers: +86 184 0771 4607
Last updated: August 27, 2026