Coffee science and gastronomy

Roundness of the coffee

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“Roundness of the coffee” is one of the most common terminologies in modern sensory evaluation. As there are some controversial definitions that trying to elaborate the roundness, I wonder that roundness of a coffee is just like a ghost, because lots of us are talking about it. But few have seen.

Roundness of the coffee belongs to the mouthfeel category of sensory evaluation which also has a major relationship with the behavioural structure of the coffee’s body.

Before we get into roundness, let’s have a profound dig towards the texture and viscosity of the coffee. What is the texture of the coffee? Does viscosity belong to texture? or viscosity and texture are two distinct? Most of the sensory evaluators believe that viscosity stands within the texture category. But surprisingly it is not. Viscosity is the rate of the flow of liquid under a force which occurs from the friction between its (fluid) particles.

Texture is a rather different attributes that perceived by sensors within our mouth.There are three different properties that evaluators have to focus when they evaluate texture. They are known as mechanical (measurement perception of the physical activities of a liquid or respond upon stress), geometrical and moisture (perception of H2O and fatty oils). From above, geometrical category talks about the understanding or the perception of the liquid particles. Such as how fine or big particle is, how hard a particle is or how low the possibility of finding a particle within a liquid (smooth or silkiness).

Now we come to the core of this so called confusion. “The roundness of the coffee”, here we too talk about the particles of the coffee. So it should be within the geometrical category, some might argue. If so, how would you understand or measure the perception of a roundness of a particle? How would you calculate the roundness? Therefore, from arising questions like this we can come to a conclusion that roundness does not just belong to the geometrical category.

As focused concentration is on roundness of the body or a particle, if we look precisely we can understand a round particle should have the ability to rotate or roll along an angled or curved surface. Therefore, roundness of a particle can be brought out as a deduction from viscosity and texture’s geometrical property category as the “rate of flow of the liquid without being forced”

Hence we can define the roundness of a coffee as, “the rate of flow of the coffee without being forced”

Accordingly, if we are to understand or summarise above by mathematically; for an isolated single particle, the roundness of a coffee should be to proportional to frictional coefficient of tasters tongue and the coffee particle.


2 thoughts on “Roundness of the coffee

    • Thanks for the comment Greg. It is rather difficult to elaborate roundness in one word. We can use viscosity to understand it. Viscosity is the rate of the flow of liquid under a force , therefore. roundness can be simplified as the flow rate of a liquid without being a forced to do so.


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