Why Does Chocolate Need To Be Tempered?
Most of the chocolate we know and love consists of cocoa solids, sugar, and milk solids that are emulsified with cocoa butter—the fat extracted from cocoa beans that, when crystallized, gives the chocolate its physical structure. When melted, these crystals (six-phase polymorphic ones, in case you were curious) are broken apart, and all those components separate into microscopic clumps. When the chocolate recrystallizes and solidifies once more, it's nothing more than a shadow of what it once was: grainy, crumbly, discolored, and utterly disappointing. That's not the kind of coating you want on your chocolate-dipped fruit, or on chocolate-dipped anything.
If melted chocolate is going to reset into the gorgeous, glossy dessert covering it was meant to be, it needs to be "tempered." Tempering chocolate is the process of controlled cooling and agitation that creates teeny, tiny crystals that are evenly sized and arranged in perfect alignment. And the good news is that all this microscopic mumbo jumbo is easy to do at home, even if you've never worked with chocolate before. You don't need a menacing industrial machine, a large marble slab, or any other specialized equipment that professionals use. All you need is a bowl, a whisk or silicone spatula, and an instant-read thermometer.
Begin by chopping your chocolate evenly into small pieces, then put two-thirds of it into a heatproof bowl. I prefer to melt my chocolate using the microwave, but if you don't have one of those, place the bowl over a pan filled with about 2" of simmering water on the stove and give the chocolate a gentle stir every minute or so until it's fully melted.
Once you have a bowl full of melted chocolate, remove the bowl from the stove and wrap the base in a towel to help keep it warm, then add the remaining chopped chocolate and get to stirring. The solid chocolate, which is still tempered, provides seed crystals for the melted cocoa butter to recrystallize around; the stirring helps evenly disperse all the solid bits within the new crystalline structures. Stirring also rapidly drops the temperature of the mixture so that those structures can set.
After about a minute of stirring, check the chocolate's temperature. For dark chocolate, you're looking for a temperature between 88-90 degrees Fahrenheit; for milk chocolate, you're looking for a reading of 86–88 degrees; and for white chocolate, 80-82 degrees. It might take a good bit of stirring before you reach the ideal temperature, so just be patient. Once you've hit the right temperature, use your tempered chocolate immediately.