In this article, I'll touch on the basics of melting and tempering chocolate.
What's the big deal? Don't I just melt chocolate like melting butter?
Chocolate is a pretty amazing food. The melting point of chocolate is just below human body temperature. This low melting point does makes it very easy to melt. Unfortunately, chocolate can burn if heated over 200°F (95°C). Another potential problem when working with melted chocolate is "seizing". Chocolate is an extremely dry food. If a little water comes into contact with melted chocolate, the sugar and cacao in the chocolate will immediately absorb the moisture and clump up. This event is called seizing.
Melting Chocolate
There are several easy ways to melt chocolate. The microwave oven method is the easiest but works best when using a small amount of chocolate (less than 1 pound). The chocolate should be in relatively small pieces (chocolate chips also work well), so if you're using chocolate bars or blocks, you'll want to cut the chocolate into smaller pieces first. Microwave in short bursts, about 30 seconds at a time, and stir between each microwave session to provide even heating. At some point, the chocolate will be warm and the pieces will hold their shape as you pull it out of the microwave oven, but they will be slightly shiny and mush as you stir it. Keep stirring and allow the residual heat to melt the rest of the chocolate. If done properly and gently enough on high quality tempered chocolate, this method can result in melted chocolate that is still tempered. Heat it too much and you'll lose the temper, so it's important to stop as soon as the chocolate is about to melt.
The double boiler method uses a little more equipment, but gives you the most control while melting chocolate. You can melt larger quantities of chocolate with this method and use larger pieces (up to 2 ounce blocks). Select a heat proof bowl to place your chocolate in. Put about 1/2-in. water into a pot and place the bowl on top of the pot. Make sure the bottom of the bowl doesn't touch the water. Now you have a double boiler.
Put the bowl aside and bring the water to a boil. If you're melting a small amount of chocolate, you can simply take the pot of water off the heat. If melting a larger quantity of chocolate, keep the pot on the heat and turn it down to a bare simmer. Place the bowl of chocolate on top of the pot of hot water and stir the chocolate using a silicone spatula until it has melted. Be careful not to allow any steam or condensation to enter the melting chocolate or it can seize. This is usually not a problem if you are watchful and have a lip on the bowl. You can remove the bowl from the pan whenever you need to slow down the heating process and place it back on to introduce more heat. This will prove vital while tempering.
Tempering Chocolate
When melted chocolate returns to solid form the cocoa butter in the chocolate forms a crystal structure. The strange thing about cocoa butter is that the crystal structure they take on depends on the temperature at which they are formed. If the chocolate is allowed to cool on its own, the crystals of fat will be loose, resulting in a chocolate that is dull in appearance, soft & malleable, and greasy to the touch. This loose crystalline structure has a slightly lower melting point than tempered chocolate crystals. If, instead, while cooling, the chocolate is kept at 88°F (31°C) the cocoa butter will form a dense crystalline structure. Holding the chocolate at this temperature and stirring will allow a whole bunch of these stable crystal structures to form. When the chocolate is finally allowed to fully cool the chocolate will harden into a very stable hard chocolate with a slight sheen, snap when broken, and will keep for months at cool room temperature. Tempered chocolate provides enough stability to be worked into a variety of shapes - sheets, painted onto leaves and peeled off, flowers, cups, and molds. It also helps prevent the cocoa butter from rising to the surface of the chocolate and blooming into unsightly light brown markings or coatings.
To temper, most chocolate books will tell you to fully melt the chocolate and then to pour 3/4 of the chocolate onto a marble slab and repeatedly fold the chocolate onto itself and smear it across the marble until the chocolate is a uniform 82°F (28°C). The chocolate is then returned to the remaining hot chocolate and stirred in. The final mixture is either reheated or the residual heat is enough to bring the temperature back up to 88-90°F (31-32°C).
We think there is an easier way to temper chocolate! Click here to watch a great How to Video from About.com that will have you tempering chocolate correctly in no time!
A Lesson on Melting and Tempering Chocolate