Final Project: Smart Coffee Thermo

Research

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."

The results are coincident with the ones obtained in the thesis held by Matthew James Chapko, which concludes that despite the differences in the sensorial experience of coffee depending on the expertise of the consumer, the best temperature range to serve brewed coffee is in the 40-55°C range.

Personally, I´ve made my empirical study, tasting coffee at different temperatures. I can say that I prefer coffe at 45°. For me, what really matters is that each person has different preferences in taste, flavour, and aroma. Also, depending on the kind of coffee, and outside temperature, preferences may vary.

My objective is to create a thermo in which each person can receive the best coffee according to their personal preference at the moment, and that their personalized temperature for the coffee makes it remain that way until the last sip.

Components

Operation

How the thermo will work

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.

Useful Links

• Article about variations in coffee´s temperature and their effects
• Paper about the effects of serving temperature on sensory perception and acceptance of brewed coffee

Inspiration

Chargeable cup

Thermo with thermometer

How to fusion the concepts?

Benchmarks:

• Thermo with thermometer
• Electric stove for coffee cups

Code Example

"With help from ChatGPT:"

<
            #include 
#include 
 
// Replace these with your Wi-Fi network settings
const char* ssid = "YourSSID";
const char* password = "YourPassword";
 
// Initialize ESP8266 Web Server on port 80
ESP8266WebServer server(80);
 
// Dummy variables for temperature
float currentTemperature = 25.0; // Current temperature in Celsius
float targetTemperature = 30.0; // Target temperature in Celsius
 
// Function to display the web page
void handleRoot() {
  String html = ""
                ""
                ""
                ""
                ""
                ""
                ""
                "
Thermostat Control
"
                "
Current Temperature: " + String(currentTemperature) + "°C
"
                "
Target Temperature:  °C
"
                ""
                ""
                "";
 
  server.send(200, "text/html", html);
}
 
// Function to set target temperature
void handleSetTargetTemperature() {
  if (server.hasArg("temp")) {
    targetTemperature = server.arg("temp").toFloat();
    // Here, add code to adjust your thermostat based on the new target temperature
  }
  server.send(204, "text/plain", ""); // No content response
}
 
void setup() {
  Serial.begin(115200);
 
  // Connect to Wi-Fi
  WiFi.begin(ssid, password);
  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print(".");
  }
  Serial.println("");
  Serial.print("Connected to ");
  Serial.println(ssid);
  Serial.print("IP address: ");
  Serial.println(WiFi.localIP());
 
  // Route to handle loading the main page
  server.on("/", handleRoot);
 
  // Route to handle setting target temperature
  server.on("/set", handleSetTargetTemperature);
 
  // Start the server
  server.begin();
  Serial.println("HTTP server started");
}
 
void loop() {
  server.handleClient();
  // Here, add code to read your actual temperature sensor and regulate the thermostat
  // You might also update 'currentTemperature' based on sensor readings
}
 

Videos

Later, here I will share videos of my progress and the final results.