What is Tempering and why do we care?
Tempering is a process through which chocolate gains desirable textural and visual features. In this series we will explain how chocolate enters a tempered state of consistent shape V crystals and the different ways to obtain it yourself. In this piece we will be looking at the physics of the process. Understanding the theory will enable you to troubleshoot along the way and truly understand why we go through the different steps. Instructions found online are often limited to surface explanations and best case scenarios, but as we all know, chocolate is unpredictable. In this piece, we’ve laid out clear practical instructions to achieve perfectly tempered chocolate.
Most people think chocolate can only be in one of two states: tempered or untempered. But there are actually 6 different states that chocolate can take up. For simplicity let’s first look at the characteristics of well tempered chocolate.
Unless affected by fluctuating temperatures through its supply chain, all chocolate you buy at the store is tempered (commercial brands are often emulsified as an extra buffer). Tempered chocolate possesses a familiar shiny, smooth surface, breaks with a clear snap, and melts at a consistent temperature and pleasant pace, in your mouth and not in your hand.
If you’ve ever had a chocolate bar melt in your car or purse and put it in the fridge in hopes of restoring it, chances are the chocolate will have re-solidified in an untempered state. It most likely was covered with white marks that looked like mould (it’s not mould), had a matte surface texture, and broke with a long bend/pull (almost like cheese) as opposed to a crisp snap, with a surface that melted almost immediately in your hand and had an inconsistent mouthfeel - with different parts of the chocolate melting at different rates. The taste of the chocolate might even appear to be different (more due to a mouthfeel perception than an actual change of flavour compounds).
What happens there?
Chocolate at room temperature is not entirely a solid or a liquid but a group of solid particles (cacao solids and sugar), suspended in cacao butter which stays in almost-solid form right around room temperature. These cacao solids are starches and proteins. As you may know, starches and simple sugars bind with or dissolve in water very easily, but not with fat. Meaning, when mixed with fat, they have a tendency to clump together and separate.
Cacao beans are made up of around 50% cacao butter, with the other 50% being the solids.
When examined on a microscopic level, you will see that cacao butter has the ability to arrange its particles into 6 different configurations, creatively named Shape I, Shape II, Shape III and so on. Each shape can be identified by the distinct ways in which the crystal particles arrange, and trap the cacao solids distributing them throughout the chocolate bar. In each shape, the crystals hold together in bonds of varying strengths, thereby generating varying amounts of energy, AKA have different breaking points from each other.
When you consider that temperature is just another way of measuring energy, it follows that these crystals, or polymorphic (meaning, can solidify in various crystallographic forms) shapes, each have a unique melting point determined by how much energy their bonds hold. Shape I has the lowest melting point (16-18°C), while Shape VI has the highest.
Considering our goal is making chocolate melt in the eater’s mouth, it’s very convenient that cacao butter’s range of melting points is right around the human body temperature.
In tempering, we strive to obtain chocolate made up of solely Shape V (5) crystals because Shape V has just the desired melting point for our goal, 36-37°C, where it melts in your mouth but not in your hand (the surface of the skin has a slightly lower temperature than inside your mouth, but of course any chocolate will melt once you hold it long enough).
We don’t have to worry about Shape VI (6) for now as it is only achieved after chocolate has been in Shape V for about a year and will not be something you encounter in the chocolate making process. You may have come across chocolate that has reached Shape VI if you’ve seen chocolate that has developed a dusty exterior after being left for a long time.
There are several ways to get chocolate to this consistent Shape V state and you can use any of them interchangeably. All of them seek to break all existing bonds and then create enough Shape V crystals to pull the other particles into the same pattern throughout the whole bar. You can do this either with temperature to create Shape V in the absence of others, or by introducing new Shape V crystals in either chocolate or cacao butter to do the same thing (a method called Seeding, as in, introducing a seed of the desired crystal pattern).
Shape V will always be stable below its melting temperature, but its kinetics of nucleation and growth are very slow, so once creating it we like to give chocolate a colder environment to have a better chance of multiplying to fully crystallised chocolate bar. The caveat here is the colder temperatures give the less stable shapes a chance to form, so we have to watch that we don’t go too cold and remember to bring the temperature back up to a range that shape V can tolerate but where the others break 29 - 32ºC.
What happens if we don’t temper?
Think back to that melted-then-cooled chocolate bar. Think of its features. If we melt chocolate and then cool it down without interfering with its crystallisation, we will allow a random array of all the different crystals to form. So as it cools down, once the chocolate reaches below 36º-37ºC Shape V will start forming, then when it reaches 34º-35ºC Shape IV will begin forming, at 27-29ºC we get Shape III, 21º-24ºC begets Shape II, and 16-18ºC begets Shape I.
Imagine a Lego castle where some blocks are made of ice. At room temperature, these blocks will lose their solid form and spill over on the floor. The rest of the Lego castle will cave and lean onto the remaining plastic, exposing weak spots at the seams where the ice blocks were prior. Now imagine that instead of ice, we have a bunch of random blocks each with different melting points and structures. You can deduce that this haphazard structure doesn’t make for a very stable castle, let alone a chocolate bar.
What does this mean for a baker?
Unevenly tempered chocolate will result in clusters of hard and soft chocolate, with a few seams that will be solid in the fridge but liquid at room temperature.
The cacao butter (which is white in colour) that was previously locked into a pattern together with the brown cacao solids has now spilled out of the structure and become liquid across the chocolate’s surface, clustering in parts, either in long strips like marble or small circular clusters, forming white marbled patterns on the surface of the chocolate. Something similar is happening with the sugar in your chocolate, also separating from the stable gridlocked pattern and clustering in various places.. We call this phenomenon “blooming” (fat blooming or sugar blooming).
When you touch this chocolate or try to break it, you interact with a range of interwoven particles all with different melting points. This is what gives it that strange pulling texture instead of a crisp snap.
These features will occur almost at random, influenced by the journey of temperatures the chocolate has experienced before reaching the fridge’s approximate 3ºC.
While inconsistent, these patterns can be beautiful. And sometimes they are marginal, with visual indicators but no noticeable change in texture. At Conspiracy Chocolate, when we encounter a chocolate bar like this, we sell them under the name “Bad Temper”. They are known for their unique marbly beauty and often purchased for this reason. Like snowflakes, each bar has its own unique pattern that tells the story of its temperature journey.
I personally am a big fan of untempered chocolate right out of the fridge. It has a texture of a soft ganache-y dessert without needing any additional fat or water and just melts in your mouth in a very satisfying way. That said - it would be near impossible to maintain the chocolate in this state as it will eventually set.
All this is to say that there is no state in which the chocolate is “wrong,” just different. For most of our common uses of chocolate, however, for easy sharing and eating, and for a texture made up of the cacao’s natural distribution of solids in fat in every bite, a tempered chocolate bar of just consistent Shape V crystals is the most ideal.