The importance of Micron size in chocolates

Micron size or particle size of chocolate that is achievable in chocolates via different processes are a topic of great concern to many chocolate manufacturers and chocolatiers around the world.

But why so? Why this concern to know what is the particle size achieved in every batch that a chocolate is manufactured? What properties they can achieve by doing so which is so important in the first place?

What is so important about the particle size?

Well, the answer is straightforward and complicated both at the same time.

Chocolate is basically a mixture of cocoa powder, sugar, fat and milk or milk powder. At the more basic level, chocolate is dispersion of cocoa and sugar particles covered in fat.

So, it would make sense that the distribution of these particles in the mixture is suitably sized so that the properties of the end product which in our case is chocolate, be as standard and repeatable as possible. This would ensure that the mouth feel of the chocolate remains the same every time.

The mouthfeel of chocolate

Now since we have introduced the term mouth feel, let us go into that a bit further. Mouth feel of chocolate is the feeling you get when you take a bite out of the chocolate and it melts into your mouth.

That is the signature property of a good chocolate, all consumers and manufacturers alike of chocolate believe , mouthfeel is the primary criteria. It should taste good, right?

The temperature of mouth at around 37 °c, is above the melting point of the fat within the chocolate(generally), so it melts, especially with all the shearing and grinding going on with the help of your teeth and tongue.

As is accepted worldwide, any chocolate with majority of particle size equal to or less than 30 micron will feel as a creamy chocolate on your tongue. If the majority of the particles present in the dispersion are more than 30 micron, the chocolate will feel grainy or gritty.

Human tongue loses the ability to register the graininess if the particle size are less than 30 microns.

So, there you go. That is your benchmark, and the reason for it!

But Why 30 microns?

But we still haven’t discussed why 30 microns? Who decided 30 microns as the benchmark? And what are the scientific reasons behind it.

Let’s go then.

The research that has been done.

There is a scientific method to measure the somatosensory responses of all our touch points, like hands, feet, skin etc.

It is called Von Frey Hairs (VFH). VFH are small, calibrated monofilaments which deliver a specific amount of pressure. Until recently, VFH were extensively used to detect somatosensory sensitivity in infants, adults on their hands, feet etc to determine the level of sensory perception.

The perception of food products on the oral cavity, tongue, inner cheek was largely not done. An excellent research was published in May 2019, by Scott B. Preen, Nicole M. Etter, Gregory R. Zeigler & John Hayes in an article of Nature for which I will provide the link here. I would encourage you to give the full article a read, while it may be a tad technical sometimes, it would help your inner chocolatier answer the question why 30 microns. However, I shall try to explain it below in a manner which would help you quench the thirst a bit faster.

And guess on which product the research was done? Chocolate!

So, basically a random group of people were selected and VFH was done on different parts of their tongue.

Now the key thing to keep in mind here is that they were testing for both detection and discrimination. Meaning at what pressure points the human tongue can detect a pressure point and at what point they can discriminate between 2 pressure points. And the results show that majority of the group could feel the grittiness beyond 20 microns.

The other major thing which also got established from the article was a fact which we have been telling to many of our colleagues for years. That is, the texture of chocolate will feel like the texture of the product it is on. That is, you don’t need a 30 micron chocolate on a biscuit or a cookie which in itself has a coarse texture.

GIGO

I would also like to divert your attention to one more fact. If you start with a mixture which has a higher particle size, it will require more time and energy to achieve the particle size that you want in your end product. Garbage in Garbage out. GIGO.

Now there are things which I wont discuss in this blog and leave it for a future blog post like, the raw materials being used, the processes which deliver the most effective result in terms of particle size (read conching, refining).

Tools to measure the particle size of chocolate.

One thing I would like to add here is that what methods you can use to know if your manufactured chocolate is at the right particle size or not.

Well, the best tool for experienced chocolate manufacturers is their mouth. And if you want a more finite number, you can always use the Micrometer method, a Hegman gauge or you can get it tested in a lab in a Malvern Masterizer.

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