upright=1.35, Conche (in the Imhoff-Schokoladenmuseum) Granite Roller and Granite Base of a Conche

Conching is a process used in the manufacture of

chocolate Chocolate is a food made from roasted and ground cacao seed kernels that is available as a liquid, solid, or paste, either on its own or as a flavoring agent in other foods. Cacao has been consumed in some form since at least the Olmec civ ...

whereby a surface scraping mixer and agitator, known as a conche, evenly distributes

cocoa butter Cocoa butter, also called theobroma oil, is a pale-yellow, edible fat extracted from the cocoa bean. It is used to make chocolate, as well as some ointments, toiletries, and pharmaceuticals. Cocoa butter has a cocoa flavor and aroma. Its mel ...

within

and may act as a "polisher" of the

particle In the physical sciences, a particle (or corpuscule in older texts) is a small localized object which can be described by several physical or chemical properties, such as volume, density, or mass. They vary greatly in size or quantity, from ...

s. It also promotes flavor development through

friction Friction is the force resisting the relative motion of solid surfaces, fluid layers, and material elements sliding against each other. There are several types of friction: *Dry friction is a force that opposes the relative lateral motion of ...

al heat, release of volatiles and acids, and oxidation. The name arises from the shape of the vessels initially used which resembled conch shells. When ingredients are mixed in this way, sometimes for up to 78 hours, chocolate can be produced with a mild, rich taste. Lower-quality chocolate is conched for as little as 6 hours. Since the process is so important to the final texture and flavor of chocolate, manufacturers keep the details of their conching process proprietary.McClements, D. Julian ''Understanding and Controlling the Microstructure of Complex Foods'', Woodhead Publishing, 2007, , page 654. There are numerous designs of conches.

Food scientist Food science is the basic science and applied science of food; its scope starts at overlap with agricultural science and nutritional science and leads through the scientific aspects of food safety and food processing, informing the development ...

s are still studying precisely what happens during conching and why.

History

Rodolphe Lindt Rudolf Lindt (16 July 1855 – 20 February 1909), often known by his francized name Rodolphe Lindt, was a Swiss chocolate maker, chocolatier and inventor. He founded the Lindt brand of Swiss chocolate and invented the conching machine and other p ...

invented the conche in

Berne, Switzerland german: Berner(in)french: Bernois(e) it, bernese , neighboring_municipalities = Bremgarten bei Bern, Frauenkappelen, Ittigen, Kirchlindach, Köniz, Mühleberg, Muri bei Bern, Neuenegg, Ostermundigen, Wohlen bei Bern, Zollikofen , website ...

, in 1879. It produced chocolate with superior

aroma An odor (American English) or odour ( Commonwealth English; see spelling differences) is caused by one or more volatilized chemical compounds that are generally found in low concentrations that humans and animals can perceive via their se ...

and melting characteristics compared to other processes used at that time. The Lindt chocolate company states that Lindt (perhaps mistakenly) allowed a mixer containing chocolate to run over a weekend (or possibly overnight, according to other variants of the possibly- apocryphal story). Upon returning to the device, Lindt recognised the final product to have different properties to conventionally-produced chocolate at the time, with a less granular texture and greater shine than conventional chocolate at the time, which was generally gritty when solidified owing to the presence of non-ideal cocoa butter crystals. Lindt's invention made the mass-production of

chocolate bar A chocolate bar (Commonwealth English) or candy bar (some dialects of American English) is a confection containing chocolate, which may also contain layerings or mixtures that include nuts, fruit, caramel, nougat, and wafers. A flat, easily brea ...

s more practical, eventually replacing chocolate beverages as the primary means of mass chocolate consumption.Talbot, Geoff (ed), ''Science and Technology of Enrobed and Filled Chocolate, Confectionery and Bakery Products'', Woodhead Publishing, 2009, , chapter 2.5 ''Conching''. Lindt's original conche consisted of a granite roller and granite trough; such a configuration is now called a "long conche" and can take more than a day to process a tonne of chocolate. The ends of the trough were shaped to allow the chocolate to be thrown back over the roller at the end of each stroke, increasing the surface area exposed to air. A modern rotary conche can process 3 to 10 tonnes of chocolate in less than 12 hours. Modern conches have cooled jacketed vessels containing long mixer shafts with radial arms that press the chocolate against vessel sides. A single machine can carry out all the steps of grinding, mixing, and conching required for small batches of chocolate.

Process

Conching redistributes the substances from the dry cocoa that create flavor into the

fat In nutrition, biology, and chemistry, fat usually means any ester of fatty acids, or a mixture of such compounds, most commonly those that occur in living beings or in food. The term often refers specifically to triglycerides (triple est ...

phase. Air flowing through the conche removes some unwanted acetic, propionic, and butyric acids from the chocolate and reduces moisture. Even a small amount of moisture greatly increases the

viscosity The viscosity of a fluid is a measure of its resistance to deformation at a given rate. For liquids, it corresponds to the informal concept of "thickness": for example, syrup has a higher viscosity than water. Viscosity quantifies the inte ...

of the finished chocolate, so machinery is cleaned with cocoa butter instead of water.Ranken, M. D.; Kill, R. C.; Baker, C. G. J. (ed.), ''Food Industries Manual (24th Edition)'', Springer-Verlag, 1997, , pages 438–439. Some of the substances produced in the roasting of cocoa beans are

oxidized Redox (reduction–oxidation, , ) is a type of chemical reaction in which the oxidation states of substrate change. Oxidation is the loss of electrons or an increase in the oxidation state, while reduction is the gain of electrons or a ...

in the conche, mellowing the flavor of the product. The temperature of the conche is controlled and varies for different types of chocolate. Generally, higher temperature leads to a shorter required processing time. Temperature varies from around for milk chocolate to up to for dark chocolate. The elevated temperature leads to a partially

caramelized Caramelization is a process of browning of sugar used extensively in cooking for the resulting sweet nutty flavor and brown color. The brown colors are produced by three groups of polymers: caramelans (C24H36O18), caramelens (C36H50O25), and ca ...

flavor and in milk chocolate promotes the

Maillard reaction The Maillard reaction ( ; ) is a chemical reaction between Amino acid, amino acids and Reducing sugar, reducing sugars that gives browned food its distinctive flavor. Searing, Seared steaks, fried dumplings, cookies and other kinds of biscuits, b ...

.Emmanuel Ohene Afoakwa, ''Chocolate Science and Technology'', John Wiley and Sons, 2010, , pages 43, 65–66. The chocolate passes through three phases during conching. In the dry phase the material is in powdery form, and the mixing coats the particles with fat. Air movement through the conche removes some moisture and volatile substances, which may give an acidic note to the flavor. Moisture balance affects the flavor and texture of the finished product because, after the particles are coated with fat, moisture and volatile chemicals are less likely to escape. In the pasty phase more of the particles are coated with the fats from the cocoa. The power required to turn the conche shafts increases at this step. The final liquid phase allows minor adjustment to the viscosity of the finished product by addition of fats and emulsifiers, depending on the intended use of the chocolate. While most conches are batch-process machines, continuous-flow conches separate the stages with

weirs A weir or low head dam is a barrier across the width of a river that alters the flow characteristics of water and usually results in a change in the height of the river level. Weirs are also used to control the flow of water for outlets of l ...

, over which the product travels through separate parts of the machine. A continuous conche can reduce the conching time for milk chocolate to as little as four hours.

References

External links

Conching - ScienceDirect

Refining and Conching - Grenada Chocolate

Manufacturer's illustration of production-size conche and mixing shaft
{{Chocolate Chocolate Cooking techniques Articles containing video clips

History

Process

See also

References

External links