What is a melanger, and why am I studying it?

May 10, 2019

A melanger is a stone-grinder that is used in small-batch artisanal chocolate-making. This is the under-studied step which is the subject of my Masters thesis. Melanging techniques are the subject of much debate among chocolate-makers: Lid on or off? Fast or slow? Hot or cold? Full or half-full? What order to add the ingredients? And of course, most importantly, how do I know when the chocolate is done? In this post, I’ll describe what melanging looks like and what it does and what I’m studying about this important step.

A melanger consists of a granite wheel or, more often, two granite wheels, which rotate inside a metal drum (nowadays usually made from stainless steel) on top of a granite base. The weight and rotation of the stones against one another create shear forces, which both grinds the chocolate (or whatever else is put in the melanger) and homogenizes and aerates the mixture.

It appears that French chocolate producers have been using a stone-grinder of the type now called a melanger (French, malaxeur) as part of the chocolate-making process since 1778 (Frogerais, 2017). However, its use was different than how the same machine is typically employed today. Instead of using the malaxeur only for the entire refining step, producers treated this piece of equipment as only the first step in a series of refining and texture-development phases. In this production style, the cocoa mass was kept in the melanger only until the mixture was sufficiently homogenized that it could be passed to the next step, known as broyage-affinage (refining). At the end of malaxage, the cocoa mass is described as having a pleasant flavor, but with a particle size over 100 microns, still an unacceptably grainy texture (Gasparotto, 2018).

The broyage-affinage that followed involved pulling a thin sheet of cocoa mass between rollers at 30 bars of pressure until particle size was reduced to 20 microns. Only then, and only for certain processes, was the “supplementary step” of conching recommended (Gasparotto, 2018).

This is not at all how melangers are used today. In modern, small-batch chocolate-making, melangers are used as a stand-alone refining and flavor development step. While some researchers treat melanging as a type of conching because both techniques make use of crushing and shear forces to refine, mix, and aerate chocolate (Tan & Balasubramanian, 2017), there are some significant differences in the two processes. First, as I mentioned previously, in conching all particle size reduction has already taken place before the chocolate mass enters the conch, and no further reduction in particle size will occur during the conching step (Fryer & Pinschower, 2000). In melanging, however, particle size reduction takes place in conjunction with other processes, since the cocoa mass has not been fully refined when it enters the stone grinder (Owen, 2013; Tan & Balasubramanian, 2017). Also, while in conching a chocolate producer may add cocoa butter towards the end of the process, in melanging all ingredients in their full proportions for the final recipe are added at the beginning of the process. (Owen, 2013). Finally, while the precise times and temperatures of the two processes are trade secrets for the companies that use them, conching generally appears to happen at higher temperatures for shorter times than melanging.

Although melanging is mechanically different than conching, it shares the same goals and works according to similar principles. Both methods make use of shear mixing (pressing particles between two surfaces) and elongational mixing (spreading particles along a surface) to reduce particle size (Berk, 2013).

The specific type of stone grinder known as a melanger and used in small-batch chocolate production today has found more common application as a wet grinder for Indian dosa batter and has also found some limited application with soy on a laboratory scale (Bhattacharya & Bhat, 1997; Vishwanathan, Singh, & Subramanian, 2011). Similar machines have been used for nut-grinding for nut butters or nut-based confections (Nanci, 2016). Early records of melanger use in small-batch chocolate-making are poorly documented. At least one record exists of some chocolate-makers using a modern melanger as early as 2006 (Spies, 2007). In 2007, Inno Concepts LLC, and importer of wet grinders from India to the United States, found itself with an excess of grinders in the midst of an economic recession. Upon hearing that some of their customers used wet grinders for chocolate making, the owners experimented with modifications, such as adding a cooling mechanism, to repurpose their excess motorized stone wet grinders into chocolate-making devices, and Cocoatown LLC was born (Williams, 2017). They marketed these updated grinders to the growing niche population of small-batch chocolate makers that were beginning to seek small-scale chocolate-making equipment at the time.

Melangers from Cocoatown and other producers such as Cacao Cucina are now the most common refining tool used by small-batch chocolate makers because of their scalability and low upfront capital investment (Coleman, 2014). Despite this, there is little academic literature on the use of melangers for chocolate-making. Therefore, the goal of this study is to define the effect of ambient temperature and time on melanging outcome.

Briefly, I made 3 batches of chocolate, each batch with cacao beans from Ghana. I started with 478g of beans for each batch, which were roasted at 163C for 17 minutes, then cooled, cracked, and winnowed, resulting in 350g of nibs. I added these nibs plus 125g of sucrose plus 25g just melted cacao butter to a small melanger. I ran the melanger inside of a temperature and humidity-controlled incubator, each batch at a different ambient temperature. I made batch 1 at 15C, batch 2 at 24C, and batch 3 at 38C. I sampled each batch at 0H (as soon as the original mixture combined) and then every 8H after that, so I had samples at 0H, 8H, 16H, and 24H. I took 2g samples in triplicate and analyzed them using SPME paired with GC-MS to find the volatile flavoromics profile. Those results will be discussed in another post. I also took some backup samples to measure particle size, pH, and titratable acidity, which is itself a whole other story.

So, that gives some background on the purpose and objectives of my study. Hopefully, this data can give direction to chocolate-makers who are looking for some guidance about how to optimize their melanging profiles.

Works Cited

Berk, Z. (2013). Size Reduction. In Food Process Engineering and Technology (pp. 167–191). https://doi.org/10.1016/B978-0-12-415923-5.00006-X

Bhattacharya, S., & Bhat, K. K. (1997). Steady Shear Rheology of Rice-Blackgram Suspensions and Suitability of Rheological Models. Journal of Food Engineering, 32(3), 241–250. https://doi.org/10.1016/S0260-8774(97)00027-7

Coleman, D. M. (2014). ‘ Micro-batching ’ grows up. Candy Industry.

Frogerais, A. (2017). CIE Constructeurs de machines pour les industries alimentaires , chimiques et pharmaceutiques.

Fryer, P., & Pinschower, K. (2000). Materials science of chocolate. MRS Bulletin, 25(12), 25–29. https://doi.org/10.1557/mrs2000.250

Gasparotto, T. (2018). Le Chocolat dans touts ses etats.

Nanci, J. (2016). Ask the Alchemist #176. Chocolate Alchemy. Retrieved from http://chocolatealchemy.com/blog/2016/09/15/ask-the-alchemist-176

Owen, G. (2013). How Chocolate is Made. Chocolate Science and Technology, 2, 1–12.

Spies, T. (2007). Chocolate Maker Interviews. CocoaLab. wordpress.com. Retrieved from https://cacaolab.wordpress.com/chocolate-maker-interviews/

Tan, J., & Balasubramanian, B. M. (2017). Particle size measurements and scanning electron microscopy (SEM) of cocoa particles refined/conched by conical and cylindrical roller stone melangers. Journal of Food Engineering, 212, 146–153. https://doi.org/10.1016/j.jfoodeng.2017.05.033

Vishwanathan, K. H., Singh, V., & Subramanian, R. (2011). Wet grinding characteristics of soybean for soymilk extraction. Journal of Food Engineering, 106(1), 28–34. https://doi.org/10.1016/j.jfoodeng.2011.04.002

Williams, T. (2017). Cocoatown Helps Create ‘Bean-to-Bar’ Chocolate Entrepreneurs Across the World. Global Atlanta.