20 January 20

The conching process

Diego Cortés Chief of New Product Development

The process behind Luker’s deliciously flavoured and smooth chocolate

For many consumers, there is little known about how much is done to a cocoa bean before it can be turned into chocolate. More than a mystical metamorphosis, this transformation brings nature, science and art together. To bring a chocolate couverture to life, fermented and dried cocoa beans are selected, winnowed, roasted, ground, mixed (with other ingredients), refined, and finally conched.

Continue reading below to discover more about the process behind Luker’s chocolate products:

The conching process was discovered in 1879 by the Swiss chocolate-maker Rudolph Lindt. Having accidentally left a mixer containing chocolate running overnight, he woke up to realise  that this changed the chocolate’s flavour and texture. The name of the equipment, the conche, is derived from the Latin word ‘shell’, as the traditional conche used in chocolate manufacturing resembled a conch shell.

Nowadays the conching process is the final step in the manufacturing of chocolate. Whether its milk or dark, it is an essential process that contributes to the development of viscosity, final texture, and especially flavour. Amongst the chocolate-making industry, we talk about ‘cocoa solids’ as particles that carry all the colour, taste, and most of the nutritional value of a chocolate bar. However, these particles also happen to have intense bitter and astringent notes, which are given by polyphenols or antioxidants in cocoa. Additional off-flavours such as acetic acid are also left over from the fermentation process.

 

 

This processing step, which consists mainly of mixing, shearing, and aeration of the chocolate mass at a certain temperature and for a certain amount of time, is considered a critical step for two main reasons:

  1. During conching, the tiny particles of solids (often cocoa, sugar, and milk) acquire a more uniform shape to be coated evenly with cocoa butter. This gives chocolate its viscosity, flow, and textural properties and determines the way in which the finished product will melt smoothly in the mouth.
  2. The conching process promotes flavour development through several factors such as time, temperature, and the other ingredients in the recipe. But it also removes moisture and volatile flavours (short-chained fatty acids and aldehydes) that are highly related with the origin and characteristics of the cocoa beans. This is one of the most important reasons for which the conching process at Luker Chocolate is different from other chocolate manufacturing companies.

 

Amongst the scientific community, different researchers have put forward differing opinions on how many phases there are in the conching process. Some researchers define conching as a two-phase process. In the first stage known as the ‘dry phase’, the moisture level is reduced. Some volatile acids like acetic acid caused by cocoa fermentation are removed, and the surfaces of all solid particles are covered with fat. In the second stage, called the ‘wet phase’, homogenous and paste-like fluid mass is obtained by adding more cocoa butter and emulsifiers.

 

 

On the other hand, some say that this process has three phases. This is also what we believe and perform at Luker Chocolate which can be described as follows:

1. DRY PHASE

 

Chocolate mass being transferredChocolate mass being transferred from the refiner  

 

The chocolate mass is transferred from the refiner, generally as flakes, to be heated, mixed and aerated. The primary objective of this stage is to allow the evaporation of some of the volatile acids from cocoa liquor and the water originating from the chocolate components. The total concentration of acetic acid after the dry conching stage remains approximately constant as there is no free water that acts as a vapour carrier.

 

2. PLASTIC PHASE

Cocoa flakes turning into a pasteCocoa flakes turning into a paste as cocoa butter is added

 

Next, the mass which was mixed, sheared, heated and degassed enters the second phase that we call the ‘long step’. At this stage, flavour characteristics are developed through chemical reactions (Maillard reaction and Strecker’s degradation ) given by the process’ time and temperature conditions. This is also another important step to reduce the volatilisation of acetic acids, due to cocoa fermentation.

It is called the ‘plastic phase’ because of the physical change that occurs to the mass, turning from flakes into a paste and becoming more liquid as the cocoa butter covers the solid particles. Time and temperature play a key role in this stage. The temperature is more closely related to the type of chocolate being manufactured (dark, milk or white). While time has to do with factors dependent on the quality and variety of beans used to produce the cocoa liquor.

 

3. LIQUID PHASE

 

final phase as milk chocolateThe final phase as milk chocolate is being conched

This phase is the shortest and it is where the viscosity and flow properties undergo the final adjustments, with the addition of cocoa butter and emulsifiers.

The technology used is extremely important (i.e., actual conching machinery designs are more efficient in terms of energy and time). In the conching process during the plastic phase, normally milk chocolates are conched at around 50°C to prevent the caramelisation of the product. Should the temperature be any higher, this causes lumps and sandiness in the mouth when eating the final product.

Some dark chocolates, on the other hand, can be conched up to 90°C because of their intense load of volatile by-products from fermentation. However, conching time is a big discussion point at this stage, because it is here that the quality, type and the origin of the beans play a determinant role.

Throughout the years, Luker Chocolate has built extremely close relationships with Colombian farmers, sharing knowledge and experience. This guarantees exceptional quality characteristics by the end of the fermentation process and the drying of the cocoa beans. Supported by the Colombian ‘Fino de Aroma’ cocoa beans which are naturally complex in their flavour profile with delicate fruity, floral, and herbal notes, we take great care in the application of temperature and conching time for every chocolate couverture we produce. This means Luker can deliver finished products to customers all around the world with unique, high-quality flavour experiences.

Here at Luker Chocolate, with state-of-art technology and our Colombian Fine Flavour cocoa beans, our conching process ranges from 2 to 7 hours. It is this length of time that really makes us different in terms of processing conditions during chocolate manufacturing. Other companies around the world that manufacture chocolate couvertures, working with bulk cocoa beans, can apply conching processes from 12 to 78 hours. This is due to the high levels of acetic acid and other compounds that can have a negative impact on the final flavour of the chocolate. A disadvantage in terms of production efficiency (costs and energy).

We hope that with this information, the next time you eat chocolate, close your eyes, pay attention to the texture as the chocolate melts in your mouth. Take a slight breath of air to assess the flavour and remember that behind that complexity, the joint work of science and nature is the magic behind your new sensory experiences.

The conching process is a specific step during chocolate manufacturing, which is very important for enhancing the quality of the finished product. However, long heat treatment and high shear -required for the removal of undesirable volatile compounds and moisture- present disadvantages for production efficiency and cost.

With this information, the next time you eat chocolate, close your eyes, pay attention to texture as the chocolate melts in your mouth, take a slight breath of air to assess flavour, and remember that behind that complexity, the joint work of science and nature is the magic behind new sensory experiences.

 

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