Master the Roast: Welcome to Holistic Roasters' Coffee Roasting Simulator

Note: This is a work in process. Parameters may not accurately reflect real-world dynamic... yet!

Get ready to turn up the heat! This is your Coffee Roaster Simulator and it puts you in the roaster’s seat (no beans or pressure required). Tweak the heat, ride the Rate of Rise, and see how your choices shape the roast curve in real time. Whether you’re dialing in your dream espresso profile or just geeking out on thermodynamics, this is your sandbox. Let's roast!.

Want to learn more about roast curves before diving in?
Check out our blog post: Roast Curves 101: The Chart That Makes Your Coffee Taste Amazing

Getting Started:

1. Set Initial Parameters (Before Preheat):
   
   • Target Charge DT (°C/°F): Set the desired Drum Temperature (DT) you want to reach before charging (adding) the beans. A common starting point is 180-220°C (356-428°F). This target also influences the ET drop dynamics at charge. You can switch between Celsius and Fahrenheit using the "Units" button.
   • Batch Size: Select the weight of green coffee beans you want to roast. Larger batches have more thermal mass and may react differently, including a more significant ET drop at charge (modulated by airflow and charge temp accuracy).
   • Initial Moisture (%): Set the starting moisture content of the green beans. Typical range is 8-12%. Higher moisture can prolong the drying phase.
   • Bean Density (g/mL): Set the density of the green beans. Denser beans often require more energy and may roast differently.
   • Drum Speed (RPM): This is an initial setting before preheat. Optimal drum speed helps with even heat distribution. You can adjust this during the roast too.
2. Preheat: Click the "Preheat" button. The simulator will start heating the roaster. The "Preheat Status" will show the current Drum Temperature (DT) and Environmental Temperature (ET) in your selected unit.
3. Charge Beans: Once the DT reaches your target (or you decide to charge earlier/later), click the "Charge Beans" button. This adds the beans to the roaster. You'll see an initial drop in temperatures as the beans absorb heat. The magnitude of the ET drop is now more dynamic, considering batch size, actual vs. target charge DT, and airflow at charge.

During the Roast:

Once beans are charged, you can actively control the roast:

• Gas Power (%): Adjust the gas slider to increase or decrease heat input. This is your primary tool for controlling the rate of temperature rise.
• Airflow Damper (%): Adjust the airflow. Airflow affects convective heat transfer, helps remove smoke and chaff, and can influence moisture removal and bean temperature. Airflow setting at charge now also modulates how batch size and charge temperature accuracy affect the initial ET drop.
• Drum Speed (RPM): Fine-tune the drum speed. This can affect conductive (bean-to-drum) and convective (bean-to-air) heat transfer.

Monitoring the Roast:

• Roast Info Panel: All temperatures are displayed in your selected unit (°C or °F).
  • Time: Elapsed time of the current phase (Preheat, Roast, Cooling).
  • BT (Bean Temperature): The temperature of the coffee beans.
  • ET (Environmental Temperature): The air temperature inside the drum.
  • DT (Drum Temperature): The temperature of the roaster drum surface.
  • RoR(BT) (Rate of Rise of BT): How quickly the bean temperature is increasing, measured in °C/min or °F/min.
  • Moisture: Estimated current moisture content of the beans.
  • Bean Color: A visual representation of the beans' color changing as they roast.
• Events Log: Shows important events like "First Crack," "Second Crack," control changes, and warnings. Temperatures in logs will reflect your selected unit.
• Roast Chart: Plots BT, ET, DT, and RoR over time. The Y-axes will adjust to your selected unit.

Key Roast Milestones:

Approximate Celsius temperatures are given, with Fahrenheit equivalents in parentheses. Actual values can vary.

• Turning Point (TP): The point after charging where the bean temperature stops dropping and starts to rise.
• Drying Phase: From charge until beans turn yellow (around 150-160°C / 302-320°F BT). Focus on steady RoR.
• Maillard Phase (Browning): From yellowing to First Crack. Development of aroma precursors. RoR typically starts to decline.
• First Crack (FC): An audible popping sound. Usually occurs around 195-205°C (383-401°F) BT.
• Development Time: Time from First Crack to dropping the beans.
• Second Crack (SC): A more rapid, crackling sound. Occurs significantly after First Crack.

Ending the Roast:

• Drop Beans: Click the "Drop Beans" button when you've reached your desired roast level.
• Cooling: Beans are rapidly cooled.
• Roast Outcome: A detailed analysis will be displayed. Temperatures will be in your selected unit.

Profile Management:

Saved and exported profiles store temperature data internally in Celsius for consistency. When loaded as a reference, it will display on the chart according to your current unit selection.

• Save Profile: Saves the current roast data.
• Load Stored Profiles: Load a saved profile as a "Reference Curve".
• Import Profile (JSON): Load a .json profile as a reference curve.
• Export Current Roast Data: Saves the current roast as a .json file.
• Clear Reference Curve: Removes any reference profile from the chart.

Understanding the Parameters (Advanced):

Ranges are given in Celsius with Fahrenheit in parentheses. Internal calculations are always performed in Celsius.

Parameter	Range/Value	Impact
Target Charge DT	~160-250°C (320-482°F)	Higher charge temp means more initial energy. Accuracy influences ET drop.
Batch Size	10-25 kg	Larger batches have more thermal inertia.
Initial Moisture	8-12%	Higher moisture may prolong drying.
Bean Density	1.10-1.25 g/mL	Denser beans often require more energy.
Gas Power	0-100%	Primary control for heat input.
Airflow Damper	0-100%	Affects convective heat transfer.
Drum Speed	30-60 RPM	Influences bean agitation.

Use the "Units: °C/°F" button to toggle temperature displays. Experiment and Happy Roasting!