Grinding & Conching

Once the cocoa beans have been harvested, fermented, dried, roasted, and cracked, they arrive at the grinding and conching stages in the form of cocoa nibs.

What is grinding?

Grinding is the process of converting the cocoa nibs into a fine powder and then into smooth chocolate.

In order for the coarse cocoa nibs to become smooth craft chocolate bars, they need to be ground at extreme speed and power for several days. This is achieved by placing the nibs in a rapidly spinning vessel with rotating granite stones fitted in the base.

When ground for long enough, the nibs release the cocoa butter within them, and the dry powder changes into liquid chocolate. At this stage, the cocoa butter can either be removed and sold as pure cocoa butter or kept in the chocolate to be turned into bars.

The significance of Indian spice grinders

One of the surprising heroes of the craft chocolate revolution is the simple Indian spice grinder.

Why? Well, before the early 2000s, anyone who wanted to make their own chocolate could get most of their equipment on the cheap. You can roast in a regular oven, crack and winnow with rolling pins and hair dryers, and do most of the rest by hand. But you had to invest in an incredibly expensive machine to grind and conche your beans.

That was until someone realised the similarity between Indian spice grinders and the expensive machinery in the chocolate world. These spice grinders can be found all over India in domestic kitchens; they’re readily available and not terribly expensive.

This discovery has opened the door for craft chocolate entrepreneurs ever since. Now, anyone with a little bit of capital can get the machines necessary to start turning cocoa beans into chocolate. And so many of our makers tell that exact story: “We started making as a hobby,” “It was just for family and friends,” “We just wanted to try it out,” etc.

Well, thank goodness for us they did!

What is conching and why is it done?

Conching is a form of advanced grinding that affects the flavour as well as the texture of the chocolate.

At this stage in production, other ingredients such as sugar, additional cocoa butter (for additionally silky bars), and flavourings can be added to the chocolate to give each bar its unique flavour and textural fingerprint.

Texture

As with grinding, conching makes the cocoa particles within the chocolate smaller, which makes the finished bar far smoother.

The rapid mixing and grinding of the conche machine also distributes the cocoa butter evenly throughout the newly liquified chocolate, ensuring consistency of silky texture in the solid bar.

However, if you conche for too long, the cocoa particles become too small and the cocoa butter takes over, giving a cloying mouthfeel.

If the fabled story is to be believed, the conche was invented in 1879 by Rodolphe Lindt when he accidentally left his grinder on overnight. He discovered that the chocolate he had produced was less granular and more aromatic than previous batches, and it became a staple of chocolate production.

Unconched chocolate provides an interesting texture and can still be purchased through brands such as Taza. The grain is thicker and does not melt in your mouth as easily, but it is a unique bar that we definitely recommend. It is especially interesting to sample in comparison to Pralus which are famed for their sinfully smooth bars.

Flavour

Unlike grinding, conching affects the flavour as well as the texture of chocolate due to the addition of heat and air (it’s a little bit like kneading dough to make bread).

Cocoa beans naturally contain acetic acid which gives them a sharp, acidic flavour. When the chocolate is spinning in the conche, it is heated and exposed to the air which burns away and oxidises the acid, giving the chocolate its dreamily rich rather than sour flavour.

In addition to removing chocolate’s natural astringency, the heating process adds to the chocolate’s flavour profile by caramelising the sugar within the chocolate.

The temperature applied to chocolate during the conching process varies depending on the type of chocolate being produced. Generally speaking, milk chocolate is conched at around 49 degrees Celsius, and dark chocolate at about 82 degrees Celsius (the higher sugar content of milk chocolate allows it to caramelise at a lower temperature).

Types of Conche

There are a surprising number of conches for chocolate makers to choose from, with different speeds and temperatures in each. But as with making bread, so long as you understand the process, you can modify the variables to achieve similar results.

If you conche with less air and agitation, then you need to conche for longer (as with the four-day longitudinal conche). Increase the aeration and agitation and you can decrease the time (most of our makers use these smaller, 2-3 day melangeurs).

Or, if you’re in a rush, there are high-speed conches which can adjust the air, work, and temperature to achieve a similar quality on the finish.

Sources

https://en.wikipedia.org/wiki/Conching

https://www.sciencedirect.com/topics/food-science/conching

https://www.lukerchocolate.com/en/chocolate-and-portfolio/conching-process/