While I sip on my morning cup of coffee, let's dive in together and find out what all this first crack business is about, shall we?
What is the First Crack?
First crack, which often sounds like popcorn popping, is the moment when coffee beans begin to approach the stage of actually being packaged for use. Coffee goes through two cracks when roasting, and light to medium roasts (which most roasters prefer) will finish somewhere between them.
The cracking process happens when the coffee bean expands and the moisture begins to evaporate. When the moisture creates steam, it will build up pressure that causes the beans to crack open. The first crack of the coffee bean comes at about 385°F in the roasting process. Once the roaster hears the sound of the first crack, he or she will know that this bean is beginning to reach the stage of light roast. You can continue to roast after first crack all the way to a medium roast at 426°F. The coffee beans will begin to show a beautiful golden brown colour, which is the most common colour you will see when purchasing specialty coffee.
Let's Talk About the Heating Process
Green coffee beans contain acids, proteins, sugars, and caffeine but has no desirable taste. It's the roasting process that produces the chemical reactions of these components to create the flavours we all love so much. This chemical reaction is called the Maillard (mail-ard) reaction. The Maillard reaction is all about creating a unique flavour profile of the bean. When food is heated, a reaction occurs between the sugars and amino acids.
Its this reaction that turns baking bread a golden-brown, white sugar into a caramel sauce, and transforms green coffee beans into roasted goodness. With the idea of roasting coffee (and this also pertains to other foods as well), the Maillard reaction begins somewhere around 284 to 329° F (140 to 165° C) and can create a varierty of different flavour compounds depending on how the process is allowed to continue. Once you have heat, the next challenge is controlling what your temperature will be. From the size of the coffee bean, determining whether to process the beans with wet or dry and even whether you will use a drum or air roaster, there are several factors influencing the temperature of coffee during the roasting process.
The Importance of the First Crack
In every stage of the coffee roasting process, the beans go through many processes. This is what develops those amazing complex flavours that we have all come to know and love. First crack is the easiest of all the stages to spot. Not only is it the easiest -- thanks to that popcorn sound it gives off-- but it is also useful to anticipate when it's getting ready to happen and to also understand what else is happening to the beans. This will give you better control over the roasting and the flavour profile.
While you are roasting, you not only have to pay attention to the aroma of the bean, but you also have to pay attention to the roast colour. You do not want to go so far past the second crack stage that you bake the coffee beans instead, which will cause a roast defect and a doughy cup profile.
What Happens During the Roasting Process
Some coffee roasters use names for the various degrees of roast for the internal bean temperatures found during roasting. Recipes are known as "roast profiles" and indicate how to achieve the perfect flavour. Any number of factors may help a person determine the best profile to use, such as the coffee's origin, variety, processing method, moisture content, bean density, or desired flavor characteristics. The most popular method of determining the degree of roast is to judge the bean's colour by eye. Be careful though, because this method is not always accurate. The degree of first and second crack is the more precise way to measure the flavour profile when dealing with coffee roasting.
As the coffee absorbs heat, the color shifts to yellow and then to increasingly darker shades of brown. During the later stages of roasting, oils appear on the surface of the bean. The roast will continue to darken until it is removed from the heat source. Coffee also darkens as it ages, making colour alone a poor roast determinant. Most roasters use a combination of temperature, smell, color, and sound to monitor the roasting process.
