How Colloids Affect Strength Perception
Solid particles that are smaller than approximately one micron are so small, gravity won’t act upon them while they’re in a solution. As a result, they won’t sink to the bottom of the cup and the beverage will be cloudy in appearance. These undissolved particles in the solution are known as suspended solids or colloids. The amount of colloids, in americanos and long blacks, does a lot to alter taste perceptions. Usually, a high level of colloids in a brew will inhibit the ability to taste, but this can be a positive thing — very small coffee particles coat the palate allowing a higher tolerance to bitterness.