As we know, chocolate is rather solid, without putting it into the pocket of your weekend pants. Keeping the shape is not the only one ability, it also has a number of characteristics: gloss, a uniform surface and texture, crunching on a break, not melting instantly in your hands, and also you can store it for a rather long time. If all these qualities are presented in your favorite chocolate, you can say that it is crystallized correctly.
Yes, exactly! It is all about cocoa butter - down to it, chocolate can be hard, soft or fluid depending on the temperature. It hardens when it cools because the cocoa butter molecules begin to build bonds with each other, gathering in crystals, which in turn form a crystal lattice. And it melts due to heating because the temperature breaks the bonds between the molecules, the crystals break up and the lattice collapses. Just like in water.
Unfortunately, you can’t just melt the chocolate, pour it into the mold, let it harden (crystallize) and get the perfectly predictable result, which we are all got used to. The fact is that cocoa butter molecules always strive to combine into crystals and form a crystal lattice. And there are six types of crystals in cocoa butter and they all form different crystalline structures, which indicates their polymorphism.
Crystal polymorphism - the ability of a substance to exist in various crystalline structures called polymorphic modifications
So, there are six types of cocoa butter crystals, each with a name: γ (gamma), α (alpha), β’’ (beta 2), β’ (beta prime), β (beta) and super-β (super-beta). They differ from each other by the strength of the bonds between the molecules. Stronger the bonds, more energy is needed (higher temperature) to destroy these bonds.
The γ crystal (gamma) is not in the picture since it breaks up at a temperature of 16-18 ° C - he is not a very serious guy. Just know that he exists in nature :).
In order not to tread a lot of water, you can draw an analogy with water (pun intended). And more specifically, with its aggregate states. It is a well-known fact, that water can be liquid, but if you lower the ambient temperature to zero or lower, it turns into ice and crystallizes. Ice also has several forms: loose, white and brittle, for example, snow (snowflakes) and hard, transparent (block of ice, hail). This or that type of ice is obtained under different freezing conditions. The snowflake instantly melts in warm hands, and a piece of ice (commensurate in size) will obviously melt longer. The point is in a snowflake, water crystals are weakly connected to each other, so everything breaks up at the slightest increase in temperature. In a piece of ice, bonds are stronger - therefore, it melts longer.
Making chocolate is not all beer and skittles. We want our tiles, sweets, and shapes to always turn out beautiful and tasty, so people learned how to manage the crystallization process. To crystallize chocolate correctly, it must be prepared - recrystallized. Of all six crystals, only one fits - beta (β) - they are the most stable and form the correct crystal lattice.
In the process of precrystallization we give birth to strong crystals of cocoa butter, beta, and intentionally destroy all weak crystals. When the chocolate starts crystallization, stable beta crystals line up in the correct crystal lattice. But you need a few of those: only from 0.1 to 0.2% (0.2 percent of the total volume of chocolate). With so many stable crystals they will start to line up in the correct lattice, setting an example for other crystals. If everything handled right, then we will get that kind and properties of chocolate that we used to: hard, smooth, slightly shiny, crunchy on a break, not melting in the hands.
What about super-beta?
Super-β crystal is the most stable of all cocoa butter crystals. Over time they form in solid, crystallized chocolate. In the process of precrystallization, it is almost impossible to create. And there is no use :). A lattice of these crystals can be felt: if you put chocolate on your tongue, in which super-beta crystals have already been formed, even in your mouth it will not immediately begin to melt. And holding, it is even more complicated to melt it.
No good. When the chocolate is heated to 45 ° С - all bonds between the cocoa butter molecules break down, the crystals fall apart, both weak and strong - we see the chocolate flows. If you leave liquid chocolate in the form at stable room temperature, it will solidify, of course, but during the crystallization process all types of crystals will be born at once, both strong and weak, and they will all be built into one chaotic crystal lattice. So-called wild west from different crystals. As a result, chocolate will receive undesirable characteristics: it will not crack on a break, it will instantly melt and get leave dirty hands (but why? - right, because there are unstable weak crystals on the surface that break down at temperatures below 30°C), it may have a white coating granular structure. In short, no one will say thank you for such chocolate.
Now that you understand the principle of precrystallization, you can assume that there can be several methods. And you will be right.
We consider the following methods:
Tempering; Dissolution method; Sowing (seed) method; Temperature jump; Stable beta crystals concentrate adding.
Each method is interesting in its own way, so it is worthy of its own article.