When you drink your coffee every day, have you noticed that the taste changes as it gets cold?
First you use that very hot coffee and, as the temperature decreases, you will notice subtle flavors and aromas that you had not felt before, such as sweetness, floral or fruity notes, for example.
These flavor changes occur due to specific chemical reactions that happen with the temperature change.
How do we perceive flavors and aromas?
Coffee is a very complex drink, with more than 1000 aromatic compounds that contribute to the aromas and flavors we perceive. Of these compounds, 40 contribute significantly to the aroma of coffee.
Most of these aromatic compounds are created in the roasting process , where the increase in temperature causes reactions with sugars, carbohydrates and nitrogenous compounds present in green grains.
During the roasting, from what we call the Maillard Reaction Phase , when those numerous reactions happen, breaking and forming molecules, the aromas and flavors start to magically appear! – Ensei Neto from The Coffee Traveler blog
This process creates volatile compounds that turn into gases that evaporate at room temperature. Thus, our ability to feel them is enhanced. We perceive these flavors and aromas through our tongues and noses as a variety of aromatic compounds associated with sweetness, ranging from chocolate notes to fruit notes, depending on the coffee.
Our taste receptors for acidity, bitterness and sweetness are found on the surface of the cells of our tongues. They react to the presence of certain chemicals and then transmit that taste perception to the brain. The chemicals in volatile compounds travel from our mouths to our noses to stimulate the olfactory system; a collection of organs in the nasal cavity. This process is also crucial in determining flavor and aroma.
When it comes to other flavors that we notice, various organic acids, sugars, oils and caffeine contribute to what we feel. As James Hoffman explains in the book “World Atlas of Coffee”, the chlorogenic acids found in green coffee can create a bitter taste, with quinic acid creating a bitter and astringent flavor.
An acidic aroma in coffee can increase our perception of acidity, as we learn about these volatile compounds in association with their basic tastes, for example, we have always been exposed to a lemon aroma together with an acidic flavor, which increases perception, says Verônica Belchior, Q-grader and coffee researcher.
How temperature affects extraction
If we use water at a lower temperature, some volatile compounds that are interesting in the perception of coffee may not be extracted. However, drinks like cold brew are extracted with water at lower temperatures, but a slow process that takes many hours.
Flavors and aromas at higher temperatures
According to the US National Coffee Association (NCA), the ideal temperature to serve coffee is between 82 ° C and 85 ° C .
But be careful, it can scald your tongue, as temperatures in this range can exceed your thermal pain threshold. To drink coffee at this temperature you should take small sips, absorbing only a small amount of liquid together with the inspiration of air to cool the liquid.
From 76 ° C the perception of taste and aroma begins . At this temperature, coffee releases a lot of steam, which improves the perception of aromas, but can inhibit the perception of flavor. The volatile compounds are released and evaporate more quickly.
Higher aroma levels are perceived at temperatures around 70 ° C and can be maintained up to 60.4 ° C. These aromas tend to be described as “roasted”, “earthy” and “intense”. The taste tends to be more difficult to notice here, especially with more delicate notes of coffee. In fact, research has suggested that several roasted coffees at a similar level are more likely to taste the same at higher temperatures .
The flavors we perceive at 70 ° C are mainly bitterness and, as in aromas, flavors associated with the intensity of the roasting. These notes can last until the coffee cools down by 10 ° C, over which we can detect an increase in bitterness. It has the bitterness is more intense at about 56 ° C .
Flavors and aromas as the temperature drops
At temperatures below 50 ° C , you will experience a significant change in the flavors and aromas of the coffee. The aromas are more difficult to perceive due to the reduction of the produced steam.
The bitterness begins to diminish, allowing more complex flavor notes to appear .
When the temperature is between 31-50ºC the greatest number of flavors can be noticed, especially those associated with acidity and sweetness . At about 44ºC the sweetness is more prominent and around 42ºC the bitterness is little perceived.
Between 31-37 ° C the volatile compounds associated with notes of sweet, fruity, floral, herbal, acid and nutty flavor are more prominent. This is where we really experience the defining characteristics of a coffee!
The acidity can be perceived better at lower temperatures such as 25 ° C . For example, drinking a cup of a special complex coffee with higher acidity, at that temperature it will be more vibrant, with higher levels of acidity. Such a coffee allows us to taste the full range of flavors that a single origin coffee has to offer and shows us that the same coffee can taste differently at different temperatures. The same cup of coffee would be less flavorful at a higher temperature.
the same coffee can taste differently at different temperatures.
Whether you prefer hot or very hot coffee, it is important to understand the impact that temperature has on the flavors and aromas you feel.
The higher the temperature of the water used to prepare the coffee, the greater the extraction of the coffee compounds.
