Precrystallising
The main goal of tempering is creating the best possible conditions to initiate the development of stable crystals in melted chocolate. Therefore, “precrystallising” would be a better word.
Anyone who has ever melted butter has experienced the difference between the original product and the result after melting and solidification. The same butter looks like a different product: the butter is discolored. The same phenomenon occurs when solidification chocolate. There the change is also a result of a modified crystal structure.
Stable Crystals
Chocolate contains cocoa butter. Cocoa butter is a polymorphic fat: it can crystallize in 6 different forms, each having its own melting point. Only one of these crystal forms, the beta form, is stable. And precisely that form is necessary for the glare, hard breaking and shrinkage of the processed chocolate.
What is Tempering?
A block of couverture contains large quantities of stable crystals. Processing of chocolate starts with melting. The recommended temperature to do that is approximately 45° C. In that temperature zone all germs will be melted without any risk of burning the chocolate. But on that temperature also the stable crystals are destroyed. The recreation of sufficient amounts of stable crystals necessary to achieve a perfect finished product, is known as “tempering”. However, that word is not well chosen. It creates confusion and is an inexhaustible source of misunderstandings. A much better and more clearly defined concept, is “crystallize”.
Precrystallising: Creating The Right Conditions
Precrystallising is the creation of stable crystals than can multiply. These stable crystals are formed when the temperature is still about 27° C. But during cooling, from 30° C a first set of unstable crystals is formed. They are not very viable, and if there are not too many of them they can easily be destroyed again by increasing the chocolate’s temperature just a few degrees. The stable crystal is strong enough to survive and to multiply.
The Importance of Temperature, Time and Motion
In practice, a proper temperature zone is a necessary but not sufficient condition for good tempering. Time and movement are as important as temperature. The process of cooling and heating must be done quickly enough to minimize the creation of unstable crystals. On the other hand, the multiplication of stable crystals also takes time. Movement is important to accelerate the cooling and to distribute the stable crystals homogeneous over the fluid chocolate.
