The first concept that you need to understand about coffee brewing is the importance of variables.
variable noun var·i·able | \ ˈver-ē-ə-bəl \
- an element, feature, or factor that is liable to vary or change. “there are too many variables involved to make any meaningful predictions”
Coffee brewing has three main steps: the grinding of the coffee, the bloom (hydration of grounds), and the extraction. If you delve deeper into these steps, more variables appear. Every single one of these variables are important to the coffee brewing process– they will affect the cup of coffee you produce.
Variables that affect coffee flavor: time, weather, water temperature, pressure, grind size, coffee freshness, quality of coffee, water quality, roast type, coffee species, and brew method.
Step 1: Coffee Grind
I like to break up the grind step into 4 sections, which are all very important.
The first section I’ll cover is grind size. Coffee beans need to be ground before beginning a brew process. Generally in non-traditional high end coffee brew methods the goal is to have an even grind size. I.E. the size of the grounds should be consistent, this is needed to ensure there is an favorable extraction of coffee.
Next we will talk about how fresh the coffee is when you grind it. Raw coffee beans come from cherries that grow on small shrubs or trees. The final product off of the farm is the raw coffee bean, which next needs to be roasted. In the roasting process the coffee bean is roasted to temperatures over 400 degrees F, this develops the coffee flavor. After roasting coffee the beans need to rest for at least 8 hours to allow for Carbon Dioxide(Co2) degassing. This further develops flavor, the best time to drink coffee and when it is at its peak flavor is about 24-48 hours after roasting. After that time frame coffee flavor begins to deteriorate and lose characteristics. So it is important to grind coffee fresh to have the best flavor profile.
The third section focuses on the importance of fresh grinding, grinding right before brew process. Similar to roasted coffee, as soon as you grind coffee it quickly loses flavor. So it is important to grind coffee < 5 minutes before you begin the grind process. The same degassing process is what is causing the coffee to lose flavor. The final important variable is the ratio of coffee to water.
When we talk about the coffee to water ration we are always aiming for whats called The Golden Ratio. The Golden Ratio is the perfect balance of coffee grounds and water that leads to the best flavor in extraction. The Golden Ratio is more of a theoretical ratio because the ratio is different for every single different coffee brew method. One way to know how to achieve the Golden Ratio is precise measurement of water and grinds.
Step 2: Coffee Bloom
Coffee bloom is when coffee grounds are hydrated, this triggers a chemical reaction that releases Carbon Dioxide(Co2). This chemical reaction is important for getting rid of unfavorable flavors. This step is important to prepare the coffee for the extraction step. By using a bloom technique your coffee will be more complex and flavorful.
You may be asking, why does the bloom affect flavor so heavily? Co2 has an interesting characteristic, it creates a barrier between coffee and water. This makes your extraction process difficult and results in sour and under-developed cup of coffee. During the bloom process the coffee releases much of the Co2 it developed during the roasting process. This degassing of the coffee allows for the water to come fully into contact with the coffee to impart a full and complex flavor profile in the final cup.
Step 3: Coffee Extraction
The final step of most brew methods is the extraction. This is when the liquid is extracted from the solid coffee grounds. This generally is done using a filter, which stops the grounds from flowing into the final cup. During this step you lose most of the control you have over the coffee. The steps that you have taken previously account for most flavor differences at this point. For example the water temperature and grind size are more important than the way that you pour the water into the brew device.
Something that I have learned is the importance of being prepared and planned for brewing. Knowing the techniques, time cues, and visual signs are vital during the extraction process to know that everything is going well.
The extraction process will result in different types of coffee flavors and characteristics. Strong, weak, hollow, full body, smoothness, etc.
Hopefully this introduction to coffee brewing gives you an understanding of the sheer complex nature of coffee brewing. This series will continue to develop so stay tuned for more lessons!