Why does good chocolate snap, shine and melt in your mouth?
Chocolate is solid on the shelf and liquid on your tongue, because its fat can freeze into six different crystals and only one is the one you want.
▶ Start the storyGood chocolate melts in your mouth because of its fat. Cocoa butter typically has a melting point of around 34 to 38 degrees Celsius, so chocolate is solid at room temperature but readily melts once inside the mouth, just below body temperature. But there is more to a bar than melting, because the snap and the shine come from the way that fat has crystallised.
Like all fats, cocoa butter is made up of several , which solidify at different temperatures and rates. When they crystallise, they can form six different structures, traditionally named I through VI, and only one of them, form V, produces the snap and gloss people want. This ability to form different crystals is called . The six forms melt at different temperatures, from 17.3 degrees for form I to 36.3 for form VI, and the denser, lower-energy ones are harder to melt. A uniform form V structure gives a smooth texture, and snap.
Melting points of cocoa butter crystal forms
°C
| Melting point | |
|---|---|
| I | 17.3 °C |
| II | 23.3 °C |
| III | 25.5 °C |
| IV | 27.5 °C |
| V | 33.8 °C |
| VI | 36.3 °C |
Getting there is called tempering. A chocolate maker cools liquid chocolate while stirring it until a small amount of cocoa butter crystallises, then warms it again to keep only the most stable crystals. These act as , starting points for the rest of the fat to set around. Only 1 to 3 percent of the fat needs to be crystallised first.
Skip it and trouble follows. If chocolate melts in a hot room and then sets untempered, unstable crystals form and can leave white patches called fat . Untempered chocolate can also feel gritty, because it can contain crystals that melt at temperatures above that of the mouth. Tempering was developed by 1931, long before anyone understood how it worked. Skilled chocolate makers check a temper by touching chocolate to their lip and feeling for a cooling sensation.
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Recap
Cocoa butter can freeze into six crystal types, and tempering seeds the stable form V, which gives snap, gloss and a melt at mouth temperature.
💡 A trick to remember it · Six crystal shapes, one winner: tempering is picking the Form V team before the fat sets.
Surprising fact · Tempering was used from 1931, but its effects on crystals were not understood until the 1970s.
Sources (2)
No source, no claim. Every fact in this lesson (15 claims) cites at least one of these.