Tempering of chocolate

As far back as 300 years ago, the food we call chocolate today was known as "food for the gods". The way from the cocoa bean to the melt in your mouth requires high-precision machinery. Bühler AG in Uzwil is the world market leader in the manufacture of machines for chocolate production. "More than 70% of the world's chocolate is produced with Buhler solutions." [1] This manufacturing process involves both cooling and heating. Temperature control units from REGLOPLAS are used here in conjunction with REGLOCHILL cooling units.


The NOVATMS 500 ball mill is used in the cocoa processing process to grind the broken cocoa, whereby cocoa nibs are processed into liquid cocoa mass. Pastes, compounds, creams for fillings and coatings can also be produced with the agitator ball mill.


During the grinding process, the high pressure and friction generate a large amount of energy which heats up the stator and rotor of the agitator ball mill; this energy must be removed from the process in order not to influence the quality of the ground product.

The REGLOCHILL RC2E 80/Z/X chiller is used here, a joint venture of REGLOPLAS and Industrial Frigo. The cooling water from the chiller is used to cool the stator and rotor of the agitator ball mill, enabling the process to maintain a constant temperature and ensuring uniform quality. In addition, the holding tanks of the agitator ball mill are kept at a constant temperature in order to avoid a reduction in the quality of the semi-finished product. This is done with a temperature control unit which maintains the tank temperature between 40 and 45 °C, as the cocoa mass solidifies during cooling. However, if production is interrupted or the mill stops overnight, the ball mill must be kept at 45 °C with the temperature control unit so that the chocolate mass in the mill does not solidify.


The grinding chamber of the agitator ball mill allows grinding at low temperature in only one process step. The resulting semi-finished product has a constant product quality and is therefore the ideal solution for the fine grinding of various masses in the chocolate manufacturing process.

In most cases, the raw materials and aromas in a chocolate recipe, including the quantities, are a closely guarded secret of the manufacturer. A Buhler mixer is used to ensure that the individual raw materials are thoroughly mixed before chocolate production enters the milling process. The Chocolate Application Center of Bühler AG in Uzwil offers ideal conditions for customers to develop new recipes, compare process steps, and optimize processes.


For industrial trials, the Buhler SMXM 400 mixer with a filling capacity of 400 kg is used, which evenly mixes and kneads the formulation components. The mixing process uses shearing and kneading technology to produce a homogeneous paste-like mass from dry ingredients such as sugar and milk powder and from liquid raw materials such as cocoa mass and cocoa butter. The outer wall of the mixer is double-walled and thus the process chamber is kept at a constant temperature in the range of 40-50 °C depending on the formulation by a Regloplas 90S temperature control unit for water.


After rolling, the powdered chocolate is filled into conches for conching. Here the chocolate is refined and loses its bitter cocoa flavour. Due to friction and shear forces of the agitator in the conche, the chocolate is heated to 60 - 80 °C and liquefies again. This stirring process can often take more than 6 hours. The Elkolino laboratory conche is used in the Chocolate Application Center.


With a capacity of 5 kg, it is more of a miniature version of the original conches, which with 1.5 - 12 t are usually many times larger.

[1] Annual Report Buhler AG 2018
[2] Figure 1 Buhler AG
[3] Figure 2 Buhler AG
[4] Figure 3 Buhler AG
[5] Figure 4 Buhler AG



Regloplas AG
Regloplas AG is a family-owned company that has specialised in the development and production of intelligent temperature control systems with Swiss quality for more than 55 years. These ensure maximum process stability through exact control accuracy in the temperature ranges. Regloplas AG offers its customers worldwide complete temperature control solutions for highly sophisticated manufacturing processes and is thus a market leader.


Buhler AG
The company holds world-leading market positions in technology and processes for grain processing for flour and animal feed, but also for the production of pasta and chocolate, die casting, wet grinding and surface coating. The core technologies of the company are in the field of mechanical and thermal process engineering. The Buhler Group operates in more than 140 countries, employs some 13,000 people worldwide, and generated sales of CHF 3.3 billion in the financial year 2018.

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