Culinary Chemistry: Tempered Chocolate for Valentine’s
by Jenn Oliver
I love to make food creations as gifts for holidays, because I communicate through food (definitely better than through words). With words I find myself trying to be very precise, searching rather unsuccessfully for the most succinct way to express a thought. However, with cooking, I let loose a little more – I find the constraints and structures of recipes to actually encourage a bit of play. It’s one of the reasons why I have come to love gluten-free cooking, because the restriction in effect serves as an impetus for ingenuity; so amidst all of the rules surrounding the preparation of food, I find the freedom to express myself. Today, I tempered chocolate to tell my husband, “I love you” for Valentine’s.
Tempering chocolate is one of those techniques that is all about rules. It takes care, patience, and most of all, constant attention. A bit of a hassle if you don’t have a temperature controlled device – but, if dipping fruit or other chocolaty Valentine’s confections, there are definitely some advantages to using tempered chocolate. For one, the melting point of the chocolate is higher, so it doesn’t melt as easily, making it less messy to eat. Tempered chocolate is also prettier. It has a more glossy sheen to it, and snaps a bit when you break it apart. Besides aesthetics, tempered chocolate is less likely to bloom – the process where fat rises to the surface giving chocolate unattractive gray splotches.
What makes it so different from just melting chocolate and letting it cool? It all has to do with the arrangement of the crystal structure of the molecules within the chocolate. Just as when water cools to form ice, as chocolate cools its molecules rearrange into a definitive structure. Depending on the conditions and temperatures it encounters, different crystal structures will form (hence, chocolate is polymorphic in character), imparting varying qualities to the chocolate. The types of crystals responsible for tempered chocolate’s awesomeness are called b-crystals, the most stable form of chocolate.
How does one guarantee happy beta-crystals in their chocolate? The trick is in maintaining the proper temperatures at each stage of the tempering process. The exact temperatures needed vary with the type of chocolate, but generally I like David Lebovitz’s method: one heats dark chocolate until about 46º C (115º F) over indirect heat (such as a double boiler) to “erase” any current crystal structure in the chocolate. Then, it must cool rather quickly and evenly down to 27º C (80º F) and is often then “seeded” with a piece of solid chocolate to help ensure proper formation of the beta-crystals. After that, the chocolate is then reheated, but only to about 31-33º C (88-91º F) (white and milk chocolate should be tempered at slightly cooler temperatures). If the chocolate warms up too much, the crystal structure is “erased” and the tempering must be done all over again. Too cool, and it’s awfully difficult to dip those strawberries. It helps to have an accurate thermometer, as you can see the appropriate temperature window is rather narrow.
Can this be done without a thermometer? Well, I tried it this weekend, and was successful. It took a lot of constantly moving the pot on and off the heat, incessant stirring, and I used the back of my hand as a temperature gauge. Let’s just say that this is not the ideal way for tempering, but if you have a good sense for temperature and can watch your chocolate like a hawk, it could work. But don’t worry, there’s an even easier way to dip your strawberries into tempered chocolate bliss!
Much chocolate that one can buy in the store is already tempered. All you have to do is just make sure to melt it slowly and don’t let it get too hot, and you won’t destroy the b-crystal structure already obtained for you by the manufacturer. However, if you do accidentally overheat the chocolate above the magic 32º C (91º F), you will have to cool it and redo the tempering process. In fact, this is the method that I would recommend – if the consistency isn’t thin enough to easily dip at these temps, you can always add in a little oil to thin it out.
That’s it! Not even much chemistry involved in tempering, just a little crystal rearrangement and some babysitting. Dip whatever you like – fresh fruit, candied fruit, truffles… many confections benefit from a pretty chocolate coating. It’s a perfect easy way to say “I love you” this Valentine’s Day, or any holiday.