If the blade temperature of the coffee grinder is too high, what impact may it have on the flavor of the coffee?

When the coffee grinder works at a high temperature, it will accelerate the loss of volatile aromatic substances in the coffee beans. Coffee beans are rich in aroma components such as aldehydes and esters, which are essential to the flavor level of coffee. When the blade of the coffee grinder heats up due to long-term operation or high speed, some aromatic compounds will volatilize in advance during the grinding process, resulting in a weaker aroma of brewed coffee and a monotonous flavor. In addition, high temperature may also cause the surface of the coffee powder to be slightly charred, producing an unnatural roasted or smoky taste, covering up the original floral and sweet aroma of the coffee.

During the grinding process, the coffee grinder will greatly increase the surface area of ​​the coffee powder, making it more susceptible to oxygen contact. If the blade temperature is too high, it will further accelerate the oxidation reaction, causing the coffee flavor to decay rapidly. In a high temperature environment, the acidic substances in the coffee will decompose faster, making the sour taste of the coffee dull and losing its fresh fruity aroma. At the same time, the oil in the coffee beans is more easily oxidized at high temperatures, producing a "stale smell" similar to old nuts or cardboard, especially after the coffee powder has been stored for a period of time, this deteriorated flavor will be more obvious.

When the temperature of the coffee grinder blade is too high, the sugar substances in the coffee powder may undergo a caramelization reaction, increasing the unpleasant burnt bitterness. In addition, high temperature will also intensify the Maillard reaction, making the bitterness of coffee more prominent. On the other hand, high-temperature grinding may destroy the cell wall structure of coffee beans, release more tannins and polyphenols, causing the coffee taste to become rough and astringent, affecting the overall balance.

The blade of the coffee grinder may undergo slight thermal expansion at high temperatures, causing the gap between the blades to change, thereby affecting the consistency of grinding. If the grinding temperature is too high, the particle distribution of the coffee powder may be uneven, producing too much fine powder or coarse powder, making it easy to "over-extract" or "uneven extraction" during extraction. In addition, high temperature will also cause the oil in the coffee powder to seep out, causing the powder to stick together and agglomerate, further affecting the flow of water and reducing the extraction efficiency.

The high temperature problem of coffee grinders has different effects on coffees of different roasting degrees and brewing methods. For example, Italian coffee requires extremely fine grinding, and the friction of the blades generates more heat. High temperature has a greater impact on the sweetness and balance of espresso. The flavor substances of lightly roasted coffee beans are more fragile, and high-temperature grinding can easily make their floral and fruity aromas and sour tastes bland; dark roasted coffee beans are relatively less affected because of their heavy flavor.