What is the best drinking temperature for coffee? Why does the coffee taste bad when it is cold?

The freshly brewed coffee is fragrant and rich in flavor. After cooling, it is inevitable that there will be some bad flavors such as wood and almonds.

Why is the taste of freshly brewed coffee so different from that of cooled coffee?

Lovers of hand-brewed coffee may know that when tasting coffee, it needs to be tasted at high, medium and low temperatures, and the flavor of a cup of coffee varies with different temperatures. There are two main aspects of this situation, one is the human senses, the other is the change of coffee.

First of all, let's talk about the senses of human taste buds. Our taste buds can perceive five kinds of taste: sour, sweet, bitter, salty and fresh, while salty and fresh coffee rarely appear, so our perception of the taste of coffee is mainly reflected in sour, sweet and bitter. Different temperatures also affect the perception of taste buds.

Taste is the most sensitive to bitterness, even if there is only a little bitterness, the taste buds will be reflected to the brain immediately. The bitterness is also more obvious as the temperature drops, just like why it is not so bitter when drinking traditional Chinese medicine when it is hot, but it is extremely bitter when it is cool. The reason is that when the temperature is too high, the hot feeling of the liquid in contact with the mouth will overshadow the perception of the taste buds and reduce the taste sensitivity. As a result, the bitterness of medium and deep roasted coffee is relatively high, and when it is completely cold, it becomes difficult to taste.

Our taste buds are most sensitive to sweetness when it is close to human temperature, just like adding a packet of sugar to a cup of hot water and tasting it at different temperatures, you will find that the sweetness is most obvious between 30 and 42 ℃.

Acid is more interesting, it will not feel obvious difference with the change of temperature, also put lemon juice in a glass of hot water, taste it at different temperatures. So one of the reasons why some lightly roasted coffee turns sour after cooling is that the bitter substance of light-roasted coffee is generally small, mainly sweet and sour and other flavor substances, when the temperature drops, the sweetness decreases, then it highlights the sour taste.

Let's talk about the changes in coffee. The bad taste of coffee after cooling is mainly due to "oil oxidation" and "pigment oxidation polymerization".

Oil oxidation is more obvious on shallow roasted coffee, and friends who observe it carefully may find that there is a layer of oil floating on the liquid surface after shallow roasted coffee is cooled. This layer of oil is very easy to deteriorate in direct contact with air (oxygen) to produce a strong sense of acidity, and this layer of perishable oil is also the source of fuel consumption.

Oil oxidation

Pigment oxidative polymerization, simply understood that coffee beans in the baking process will produce "brown pigment" (caramelization reaction), mainly to provide coffee with caramel, chocolate and other flavor. This part will oxidize and deteriorate over time, and the flavor will gradually become bitter. The coffee stains on the coffee cup and the blackening of the edges of the filter paper after brewing are the products of oxidative polymerization of pigments.

What is the best drinking temperature for coffee?

To sum up, if you want to taste more and better flavor of coffee, the temperature of coffee is the best close to that of the human body. And the oxidation of coffee is deepened with time, therefore, coffee is still drunk as soon as possible, coffee heating can not return to the original taste.