Grinding and conching cocoa beans are two portions of the bean-to-bar artisanal chocolate-making process, a popular trend that has captured the imaginations of entrepreneurs and the palates of chocolate aficionados alike. The process is a near-alchemical fusion of science and art.
Making chocolate at home or on a small scale has become possible with the easy availability and affordability of the wet grinding machine or melanger, and farmed cocoa beans. The cocoa beans are sourced and then roasted, broken into nibs and winnowed to separate them from their papery shells. Grinding and conching chocolate are the intricate processes that follow, and they both require careful observation and attention to detail.
Grinding and Conching Cocoa Beans:
Defining the terms:
Once the cocoa has been winnowed, it goes into the grinder for the remainder of the process before it is tempered and molded. The initial phase involves grinding the nibs to a fine texture and subsequently a paste as the cocoa butter gets released. Additives, if any, such as sugar or dried fruits go into the grinder at this point. Extra cocoa butter, if desired, goes in a little later in the grinding process.
What does conching mean? Once a paste or liqueur is formed, the grinder continues to work on the cocoa to develop the desired flavour, texture (mouth-feel) and reduction of moisture for the right viscosity. The harsh and acidic components of the bean evaporate during this phase. They are called volatiles as they evaporate at low temperatures. This is the conching phase. It can last from a few hours to up to three days.
Some History About Conching:
The modern compact grinder used by artisanal chocolate-makers is called a melanger. It has a bowl containing rotating granite rollers and a granite slab, which are motorized. The friction caused by the the rotating stones generates heat, which evaporates the sharp-tasting volatiles and develops the texture and viscosity of the cocoa during conching.
In pre-industrial times, however, conching was arduously performed by hand, using a mortar-and-pestle-type setup called a conche, named for the conch shell shape of the receptacle.
The earliest form of the modern-day conche or melanger was invented by Rodolphe Lindt in Berne, Switzerland in 1879. It had a roller and a curved granite slab and allowed the cocoa to be thrown back over the roller with every oscillation for further grinding. It is believed that he accidentally left the grinder on overnight and discovered chocolate with a smooth and silky texture the following morning. This is how the commercially marketed chocolate we know and love today was inadvertently created. Before this happy accident, chocolate was strictly consumed as a liquid beverage.
What Does a Melanger Do?
Rodolphe Lindt’s basic design has evolved into industrial-sized machines for large-scale production as well as compact models for small-scale artisanal chocolate-making.
A modern compact melanger basically consists of a bowl with two granite rollers that rotate around a horizontal axis and a granite slab that rotates around a vertical one.
Its abrasive action generates natural heat and slowly grinds down cocoa particles and releases the fat content for the desired texture.
The friction and heat also evaporate the astringent volatiles in the cocoa, mellowing its flavour, and reduce moisture for the desired viscosity.
The nature of its movement aerates the cocoa, allowing the volatiles to escape.
What is the Grinding Process of Chocolate?
Exploring the finer points of grinding cocoa beans:
The average cocoa bean is made up of fifty percent fat and fifty percent solid particles. Grinding serves the dual purpose of breaking down the particles to a finer texture and liberating the fat or cocoa butter from the bean.
The flavour and colour of chocolate reside in the particle component of the beans. Grinding breaks down the particles to the right size to achieve the desired levels of those attributes.
One of the key aspects of grinding and later conching as well, is to obtain the ideal texture or mouth-feel, which depends on particle size. Our palates can perceive particles, and therefore grittiness, up to a particle size of thirty-five microns. So the ideal target size would have to be below that.
We use a Grind-0-meter to determine the particle size and fineness of the ground cocoa nibs. A grind-o-meter is made of hardened stainless steel and has a groove with a graded slope. The chocolate liqueur is placed on the deepest part of the groove and, using the scraper provided, drawn up the slope – the particle size is indicated where the material stops.
After the first hour, natural heat from abrasion will continue the process and it is not required to provide external heat.
If extra cocoa butter is to be added, it is melted by heating it between 150F and 250F.
Any liquor to be added is also be melted. Grinding breaks down liquor particles to about twenty microns for better blending during the conching phase.
Spices, sugar, and milk powder for milk chocolate are some of the dry ingredients that are added after the cocoa nibs have been processed for a while.
Grinding and conching usually happen seamlessly with the first process flowing into the next. There could be a refining phase in between where the particles are broken down further for reduced grittiness.
A few tips and precautions
Before grinding, it is prudent to pre-heat the bowl and rollers of the melanger as well as the cocoa nibs. This will ensure a smooth grinding process and less wear and tear to the machine. Nibs can be pre-heated in an oven to a temperature of 120F to 150F.
Care should be taken not to heat the machine above 150F as it will harm the epoxy coating.
Adding the nibs a handful at a time will ensure a thorough breaking down of the particles. It could be a long process that requires some patience as it could take up to an hour.
Care should be taken not to grind the nibs below fifteen microns as the surface area for cocoa butter will be too high, making the chocolate too viscous.
For increased fluidity, any dry ingredients can be added after the liquor component has been processed for a while.
It is imperative that absolutely no water-based ingredients are added. The chocolate will seize and the melanger will fail.
Pre-grinding the cocoa nibs can shorten the grinding time. On a small scale, the nibs can be pre-ground in a heavy-duty blender, coffee mill or juicer. We use a Champion Juicer. The finer the powder that goes into the melanger, the easier it will be as the rollers need not be raised to accommodate bigger pieces of cocoa.
Sugar can be preheated but need not be pre-ground before it is added to the melanger.
What is the Conching Process of Chocolate?
Delving deeper into what happens during the conching process
Conching is the prolonged heating, aerating and mixing of the cocoa paste to achieve the desired texture, visosity and flavour.
The three factors to bear in mind to obtain the optimum balance and desired results are shear (controlled by speed of the rollers), heat and time.
It is the process of peeling away the astringent flavours carried by the volatiles to release the essence of the cocoa bean. Some of these acidic flavours are a result of fermentation of the bean after it is harvested. Some are a result of roasting.
It also blends the ingredients like flavourings, sugar and any other dry ingredients into a homogeneous mixture with the cocoa.
As conching progresses, the cocoa particles get coated with cocoa butter for that deliciously satisfying silky texture. This also helps with workability while molding the chocolate.
Conching can be performed from a few hours to up to three days and is the chocolate-maker’s judgement call. High-shear conches can liberate the volatiles in as little as 15 minutes.
A few tips and precautions
Longer conching leads to a creamier texture. But it also strips away more of the flavors and aromas. This is where the fine art of striking a balance applies to the chocolate-making process.
Over-grinding is a common hazard and can lead to a gummy or sticky paste that cannot be molded.
Temperature during conching should not exceed 180F. The ideal range is 110F to 180F.
The risk of conching overnight is an overheated melanger which could be a fire hazard, or a loss of power leading to hardened chocolate. Almost constant supervision is unavoidable during this process.
If you have sourced cocoa beans for any specific characteristic flavour, prolonged conching might defeat the purpose by mellowing or removing its natural flavour, so proper timing is essential in such cases.
Prolonged conching can cause caramelization of the sugar, which will overpower any other flavors, and the resulting product will only taste sweet.
Conching is an exercise in precision and an alchemical process that hones the elements of cocoa and transforms it into that sumptuous bite of chocolate.
But the entire process of artisanal chocolate-making from growing the cocoa beans to packaging the final delicious product is a fascinating journey that many entrepreneurs have embarked upon.
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What is Grinding and Conching Cocoa Beans