Project Management

Research

Coffee Temperature

Coffee Temperature and Perception

Next, you will find a summary of an article published by Tasming Grant, published at perfectdailygrind.com:

"According to the National Coffee Association, the ideal serving temperature for coffee is between 82°C and 85°C. However, this would scald your tongue as temperatures in this range can exceed your thermal pain threshold. The most approved method of consuming coffee this way is through small sips or cupping ‘slurps’. This is where you only take in a small amount of liquid along with an inhale of air to cool the liquid down quickly.

Around 76°C is where flavour and aroma perception starts to take place. At this temperature, coffee releases a lot of vapour which enhances your perception of aromas, but can inhibit flavour perception. The volatile compounds are released faster and evaporate quicker here as well.

Higher aroma levels are perceived at temperatures around 70°C and can be maintained down to 60.4°C. These aromas tend to be described as ‘roasted’, ‘earthy’, and ‘intense’. Flavour tends to be trickier to perceive here, especially with more delicate notes of the coffee. In fact, research has suggested that various coffees roasted at a similar level are more likely to taste the same at higher temperatures.

The flavours that we perceive at 70°C are mainly bitterness, and as with the aromas, flavours associated with intensity and roastiness. These notes can linger until the coffee has cooled another 10°C, upon which we may detect an increase in bitterness. Bitterness has been found to be most intense at around 56°C.

At temperatures below 50°C, you’ll see a significant change in the flavours and aromas of coffee. Aromas become harder to detect; mainly due to the reduction in vapour being produced as the coffee cools.

Bitterness starts to decrease, allowing for more intricate flavour notes to come through. It’s between 31-50°C that the highest number of flavours can be detected. These will mainly be those associated with acidity and sweetness. Around 44°C is when sweetness is at its most prominent. Bitterness is least detectable around 42°C.

Between 31-37°C is when the smallest changes with the most interesting impacts can occur. Volatile compounds associated with sweet, fruity, floral, herbal, acidic, and nutty tasting notes are more prominent within this temperature range. It’s here where we really get to experience the defining characteristics of a coffee.

Acidity can be perceived best at lower temperatures such as 25°C, compared to at 44°C or 70°C."

Components

A temperature sensor is employed to continuously monitor the internal temperature of the thermo. This sensor, often a thermistor or digital temperature sensor, provides real-time data to the control system.

A microcontroller, such as Arduino or Raspberry Pi, processes the temperature readings and controls the heating element accordingly. This heating element, typically a resistive heater or Peltier module, is responsible for adjusting the thermo's temperature.

A control algorithm is developed to manage the interaction between the sensor, microcontroller, and heating element. This algorithm, could be based on Proportional Integral Derivative (PID) control.

For user interaction, a user interface is implemented, allowing consumers to set their desired temperature. Depending on the advancement of the project, this interface could range from simple LCD displays with buttons to more advanced touchscreen interfaces or smartphone apps.

Operation

Step 1: Gather Components and Tools

  1. Temperature sensor (e.g., thermistor, DS18B20)
  2. Microcontroller (e.g., Arduino, Raspberry Pi)
  3. Heating element (e.g., resistive heater, Peltier module)
  4. Power source (e.g., battery, power adapter)
  5. Display (e.g., LCD, OLED)
  6. User interface components (e.g., buttons, touchscreen)
  7. Enclosure materials (e.g., plastic, metal)
  8. Soldering iron, solder, wire cutters, and other basic electronics tools

Step 2: Design the Circuit

Create a circuit diagram showing how the components will be connected:

  1. Determine the pin connections for the temperature sensor, microcontroller, heating element, and any other peripherals.
  2. Consider power requirements and voltage levels for each component.

Step 3: Assemble the Circuit

Connect the components according to the circuit diagram:

  1. Use jumper wires, breadboards, or soldering to make the connections.
  2. Double-check all connections to ensure they are secure and correct.

Step 4: Program the Microcontroller

Write the firmware code for the microcontroller:

  1. Implement a control algorithm (e.g., PID control) to regulate the thermo's temperature.
  2. Include functions for the user interface to set temperature settings and display current temperature readings.

Step 5: Test the Circuit and Code

Power on the thermo and verify that all components are functioning correctly:

  1. Test the temperature sensor by measuring ambient temperature and comparing it to the displayed value.
  2. Test the heating element by adjusting the setpoint temperature and observing how the thermo responds.

Step 6: Build the Enclosure

Design an enclosure to house the circuitry and provide protection and insulation:

  1. Choose materials that are durable, heat-resistant, and suitable for the thermo's intended use.
  2. Consider incorporating ventilation or cooling features to prevent overheating.

Step 7: Install the User Interface

Install the display and user interface components in the enclosure:

  1. Ensure that buttons, switches, or touchscreen controls are accessible and easy to use.

Step 8: Calibrate the Thermo

Calibrate the temperature sensor to ensure accurate temperature readings:

  1. Test the thermo's temperature control accuracy by setting different temperature setpoints and observing the response.
  2. Adjust the control algorithm or parameters as needed to improve performance.

Step 9: Test and Iterate

Test the completed thermo in real-world conditions:

  1. Gather feedback from users to identify any issues or areas for improvement.
  2. Make adjustments to the circuit, code, or enclosure design as necessary based on user feedback and testing results.

Step 10: Finalize and Deploy

Once the thermo meets all requirements and performs reliably, finalize the design and assembly:

  1. Document the build process, circuit diagram, and firmware code for future reference.
  2. Deploy the thermo for use in its intended application, whether it's home heating, temperature-controlled storage, or another purpose.

How the thermo will work

Thermo Working Diagram Heating Element Temperature Sensor Control Algorithm User Interface Feedback Loop

Diagram illustrating the components and operation of the thermo. The heating element generates heat, which is regulated by the control algorithm based on feedback from the temperature sensor. Users interact with the thermo through the user interface.

Code Example

Inspiration

Videos