How to understand Coffee Baking Curve introduction to Starbucks Coffee Baking Curve

Coffee roasting curve

With the rapid heating of coffee beans during roasting, water begins to escape from the bean surface and evaporate. The escape rate depends on temperature, bean quantity, bean density and air circulation, while the standard rate of a normal roaster is 5-7 minutes when the water content of coffee beans is reduced from 11% to 2%. Coffee beans at the initial stage of roasting sometimes turn slightly white or milky white, then turn orange, and eventually become cinnamon in the later stage of roasting. This early process is often referred to as the "drying" stage.

In addition to the drying process, the aroma, acidity and bitterness of coffee (caused by the decomposition of chlorogenic acid and sugars) begin to emerge at this stage, which is also important because these are the main flavors of coffee products. This part of baking also initiates another set of chemical changes, the Maillard reaction (also known as the Mena reaction Maillard reaction).

Maillard reaction is a browning reaction that occurs when amino acids interact with sugars. The reaction can be carried out at any temperature, but high temperatures, especially those above 150℃, will greatly speed up the reaction. This series of reactions themselves are extremely complex, and you just need to remember that delicacies such as fried meat, toast or toast are mostly thanks to Maillard's reaction. Similarly, the brown of roasted coffee comes from it.

The primary goal of roasting is to heat the coffee to the desired ripeness, and then make further roasting adjustments according to the expected brewing method of the particular coffee or beans themselves. Shallow roasting can better show the natural flavor of coffee (good or bad), which is better matched with the relatively traditional brewing method. The partial depth of roasting replaces most of the original flavor of coffee with the coking roasting flavor that we are very familiar with, so the coffee beans of lower quality are almost treated by deep roasting. Deep roasting is suitable for making espresso at home (or cafe), and the basic characteristics of coffee brewing determine that the lighter the roast, the more sour the coffee.

The secondary goal of baking is to carefully control the development of coffee beans-to be honest, this is as important as the primary goal. According to the most popular belief, if the baking time or cooling time is too long, the brewed coffee will have a faint "baking" taste; if the roasting time is too short or the temperature is too high, the original taste of coffee beans may not be released in time. Coffee is prone to sudden sour, bitter and smoke taste.

There is no third goal, just pursue delicacy. We will cover the details of baking technology in more detail later, but we might as well take a closer look at the experience of coffee beans during a standard roasting process.