Chocolate and conching

Conching temperatures range from 55—85°C for sweet chocolate and from 45—55°C for milk chocolate. Higher temperatures are used for milk chocolate if caramel or butterscotch flavors are desired (24). 

Control of the polymorphic forms in cocoa butter is further compHcated by the presence of other fats such as milk fat. The fat in a chocolate can be likened to the mortar between the bricks in a mason s wall. The soHd particles in a weU-conched chocolate bed down better than the soHds in a coarsely refined and poorly mixed one (30). 

The refined chocolate mass is dry and powdery at room temperature and has a harsh, sour flavor. It is ripened before further processing by keeping it in warm chambers at 45-50 °C for about 24 h. Ripening imparts a doughy consistency to the chocolate and it may be used for the production of baking or other commercial chocolates. An additional conching... 

When concentrated aqueous samples are available, direct injection techniques can be employed. In industry, aqueous materials are frequently available from industrial operations. Examples of this would be condensates from coffee grinders, vapors from chocolate conching operations, and aqueous materials from citrus juice concentrators. 

The name conche derives from the seasheU shape of the first really effective conching machine, which consisted of a tank with curved ends and a granite bed on which the chocolate paste from the refiners was slowly pushed back and forth by a granite roUer. This longitudinal conche, the development of which is commonly attributed to Rodolph Lindt of Switzerland in 1879, is stiU used and many experts consider it best for developing subtle flavors. 

Several other kinds of conches also are used today. The popular rotary conche can handle chocolate paste in a dry stage direct from the refiners (23). The recently developed continuous conche actually Hquifies and conches in several stages and can produce up to 3600 kg of chocolate per hour in a floor area of only 34 m. ... 

Conching time varies from a few hours to many days and many chocolates receive no conching. Nonconched chocolate is usually reserved for inexpensive candies, cookies, and ice cream. In most operations, high quaUty chocolate receives extensive conching for as long as 120 hours. 

Several chemical changes occur during conching including a rise in pH and a decline in moisture as volatile acids (acetic) and water are driven off. These chemical changes have a mellowing effect on the chocolate (26). 

Counet, C., D. CaUemien, C. Ouwerx, S. CoUin, Use of gas chromatography-olfactometry to identify key odorant compounds in dark chocolate comparison of samples before and after conching, J. Agric. Food Chem., 50(8), p. 2385, 2002. 

Owusu, M., Petersen, M.A., and Heindal, H. (2011) Effect of fermentation method, roasting and conching conditions on the aroma volatiles of dark chocolate. J Food Process Pres 36,446-456. 

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