As consumers we hardly realize how much is done to a cocoa bean before it can be turned into a chocolate, but more than a mystical metamorphosis, this transformation brings nature, science and art together. In order 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, which is what we will deal within this article.
The conching process was discovered in 1879 by the Swiss chocolate-maker Rudolph Lindt, who left a mixer containing chocolate running overnight by mistake, and realized that this changed its flavour and texture. The name of the equipment, the conche, is derived from the Latin word ‘shell’, as the traditional conche used in chocolate manufacture resembled a shell.
Nowadays the conching process is the final step in the manufacture of chocolate, whether its milk or dark, and it is an essential process that contributes to the development of viscosity, final texture, and especially flavour. In the chocolate-making process, in the industry, we talk about ‘cocoa solids’ as particles that carry all the colour, taste, and most of the nutritional value of a chocolate bar, but these particles also happen to have intense bitter and astringent notes, which are given by polyphenols or antioxidants in cocoa, and some other off-flavours such as acetic acid 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 that will be discussed further, is considered a critical step for two main reasons:
During conching, the tiny particles of solids (cocoa, sugar and milk if is the case) acquire a more uniform shape, to be coated evenly with cocoa butter (continuous phase), which is going to give the chocolate its viscosity, flow and textural properties and determine the way in which the finished product will melt smoothly in the mouth.
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 off-flavours (short-chained volatile fatty acids and aldehydes) that are highly related with the origin and characteristics of the cocoa beans. This is one of the most relevant reasons for which the conching process at Luker Chocolate is different from other chocolate manufacturing companies.
Among the scientific community, different researchers put forward different opinions on how many phases there are in the conching process. Some researchers defined conching as a two-phase process. In the first stage known as 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 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, which we actually perform at Luker Chocolate, and that can be described as follows:
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.
The mass which was mixed, sheared, heated and degassed enters this second phase that we call the ‘long step’, where flavour characteristics are developed through chemical reactions (Maillard reaction and Strecker’s degradation) given by the process’ time and temperature conditions, and because of major volatilisation of acetic acid due to cocoa fermentation. It is called ‘plastic’ because of the physical change that occur in the mass turning the 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 in particular is more closely related to the type of chocolate being manufactured (dark, milk or white), while the time has to do with factors beyond the type of chocolate, where the quality and variety of beans used to produce the cocoa liquor are extremely relevant.
This phase is the shortest and it is where the viscosity and flow properties undergo the last adjustments with the addition of cocoa butter and emulsifiers.
Stating the fact that the type of technology 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 which occurs above this temperature with the consequent formation of lumps that will be perceived as sandiness in the mouth. Some dark chocolates, on the other hand, can be conched up to 90°C because of their more 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 are going to play a determinant role.
Throughout the years,Luker Chocolate has built an extremely close relationship with the Colombian farmers, sharing knowledge and experience, in order to guarantee and maintain exceptional quality characteristics by the end of the fermentation and drying of the cocoa beans. With this, and considering that the Colombian ‘Fino de Aroma’ cocoa beans 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, so that we can deliver finished products to customers all around the world bringing our final consumer a different flavour experience.
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, and this time is what really makes us different in terms of processing conditions. Other companies around the world that manufacture chocolate couvertures, working with bulk cocoa beans can apply conching processes from 12 to 78 hours, due to the high levels of acetic acid and other compounds that can have a negative impact on the final flavour of the chocolate. This is a disadvantage in terms of production efficiency (costs and energy).
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.