The Strength-Flavour Diagram
Note: * indicates the onset of generic-strength bitterness
The descriptors in this diagram can be applied to a broad range of beverages across the TDS spectrum. For instance, the TDS of a weak espresso will be almost twice as high as a very strong-tasting cezve coffee. As you calibrate to each brew method style, you should dial in your palate to the appropriate strength range for each style, before considering more nuanced tactile features like astringency or smoothness. This is cultural, not technical, and is something governed by the nature of the brew method. It’s a debate that can only be settled by your senses.
A good barometer of your preferred strength is when you don’t notice it. Like bad music or service in a restaurant, you usually notice it quickly. A good level of strength will allow the coffee to shine. A strength that is too high can overwhelm a coffee’s nuance along with your taste buds. You’ll be left with a rough, generic-strength bitterness, and a lack of complexity. A generic-strength bitterness is a strength at which the coffee tastes bitter, regardless of brew method, coffee, or roast. It’s a purely physiological response to the concentration of the coffee.
A strength that’s too low will be underwhelming and empty; your taste buds need a minimum concentration of flavour to pick up everything the coffee has to offer. Coffees described as insipid, thin, and watery are all too weak.