The combination of taste and aroma gives us what we commonly refer to as flavor. For some time now I have been searching for a way to best explain how turbulence affects brewing with regard to the flavors that end up in the cup. Most people readily understand that turbulence affects extraction but the part that is often missed is how different flavors can be highlighted or muted with turbulence. There are hundreds, maybe thousands, of taste and aroma compounds that give coffee its allure. Trifecta has always been an incredible learning tool for me and it has opened my eyes again to how turbulence affects flavor.
The legendary Ted Lingle created the SCAA Coffee Taster’s Flavor Wheel in the late 1990s. Not only does the flavor wheel look pretty cool it is a fantastic resource for the coffee industry. The May/June 2012 issue of Roast Magazine contains a wonderful article that discusses the history and use of the flavor wheel – it’s worth the read! For my purposes I want to focus mostly on the three outer levels on the aroma side of the wheel. These levels contain the terms that we most commonly identify when cupping coffees and are easily relatable.
Trifecta turbulence can be broken down into three main components: length, frequency, and power. Length is how long turbulence is present and is set through the “turbulence on” variable in recipe development. Secondly, frequency is how many times turbulence is applied to the brew slurry and is determined by a combination of “extraction time,” “turbulence on,” and “turbulence off” times. Finally, power is the force at which the turbulence is applied. Each of these factors individually is going to affect the nuance of the resulting coffee flavor so finding which one will take some practice. My typical approach is to start low and then increase as I don’t want to overwhelm my palate anything overpowering right out of the gate.
If a particular flavor is present in your coffee and you are looking to highlight that flavor this approach with turbulence may be the variable that you want to explore. Based on your knowledge of the coffee and dialing in a Full Cup you can adjust the turbulence to fine tune your recipe. In general the power is going to coincide with the density of your coffee. More dense coffees can stand a higher power of turbulence. Furthermore, the length of turbulence is a small nuance change while the frequency is a larger leap. Take a recipe that you like a lot already and move only one turbulence variable to see how it affects the flavor. If your coffee’s dominant flavors fall right in the middle of the flavor chart (nutty and chocolately) try a recipe that has medium power with equal time and frequency. When flavor clarity declines it can sometimes be attributed to too much turbulence with regard to any of the three components.
In the aforementioned article from Roast Magazine Beth Ann Caspersen describes that the flavor wheel is arranged to reflect the molecular weight of the flavor compounds. She says, “The enzymatic category and the terms associated with it actually contain a lighter molecular weight than those found in the dark purple colors seen in the dry distillation category.” This seemingly trivial fact seems to play well with the idea of turbulence in brewing. If a flavor compound has a higher molecular weight (i.e. it is more dense) it may take more turbulence to extract that compound to its fullest. I’d love to hear folks’ thoughts on that!