Taste and Smell as a Function of SSA


Taste and Smell depend - among many things - on the specific surface area (SSA) of the ingredients. This is a simple matter of geometry and physics!

The general rule is that coarsely ground spices taste less strong than finely ground spices. Why is that?

Taste "happens" when food hits your tongue. Now imagine your food consisting of little spheres or particles (with caviar, this is actually true). The taste you experience depends on the amount of interaction between the food and the sensors on the surface of your tongue. That amount of interaction is determined by the amount of surface of your tongue (do not try to change that) and the amount of surface of the food you eat (something you can change).

This is where the Specific Surface Area (SSA) comes into play.

The SSA is defined as the total surface area of a material per unit weight.

Let's go through this example to see how SSA is calculated. To simplify the math, we will use box shapes rather than spheres.

Suppose I have a (sugar) cube of 1 cm x 1 cm x 1 cm (a volume of 1 cubic cm) and a certain weight (for simplicity, assume 1 gram). The total surface area is 6 square centimeters (6 sides of 1 square cm each).

Now cut the sugar cube in half. You will end up with two pieces of 1 cm x 0.5 cm x 1 cm. These two shapes together now have a surface area of 8 square cm (two opposite sides of 1 cm x 0.5 cm, two opposite sides of 1 cm x 1cm, and another two opposing sites of 0.5 cm x 1 cm). The total weight has not changed, but the surface area has increased.

The table below shows that by cutting the pieces in half several times, the quantity of the material (as measured in the volume) of course does not change, but but the specific surface area does.

# width depth height volume SSA
1 1 1 1 1 6
2 1 0.5 1 1 8
4 1 0.5 0.5 1 10
8 0.5 0.5 0.5 1 12
64 0.25 0.25 0.25 1 24
512 0.125 0.125 0.125 1 48


The general formula for the above situation is:

SSA = n * (2 * width * depth + 2 * width * height + 2 * depth * height). 

So, in the case of box-like shapes, the specific area doubles every time each dimension of a block is halved. And the assumption is that the taste doubles with that.

For the specific situation of a cube with equal sides, the formula simplifies to:

SSA = n * 6 * width².

Practical applications are: finely ground seasoning, such as pepper or nutmeg, taste stronger than equal weight coarsely ground product.

A simple example  of the effect of specific surface area is icing sugar; it is much finer than granulated sugar and thus tastes stronger.