Caramelizing is the process of cooking sugar until it browns. When table sugar is heated to high temperatures (about 340°), it melts and darkens. As it turns from clear to dark amber, the sugar undergoes chemical changes. The sugars break apart and reform new compounds―as many as 128 different compounds have been identified during the caramel-making process―adding buttery, nutty, acidic, and bitter notes. Cooking can also "caramelize" the natural sugars in fruits and vegetables.
High-quality heavy saucepans ensure that even browning occurs. Thin or uneven pans tend to have hot spots that can burn rather than brown the sugar. It also helps to use pans with light metal interiors, such as stainless steel. Dark metal makes it difficult to see if the caramel is browning properly.
The most common techniques for caramelizing sugar are the dry method and the wet method. The former involves melting and browning sugar (by itself) in a pan. This is a tricky strategy often used by candy makers.
We prefer the wet method, which involves dissolving sugar in water, then cooking until the water evaporates and the melted sugar browns. This technique is best for home cooks because it helps prevent the sugar from burning. The addition of water also lengthens the time required for the sugar to caramelize, so more chemical reactions occur and produce more complex flavor.
Using the wet technique, add specified amounts of sugar and water to a heavy saucepan over medium-high heat, and stir only until the sugar dissolves. Once it does, cook―without stirring―until the caramel reaches the desired color. As the water evaporates, the mixture will begin to darken. This darkening will occur unevenly, but do not stir the caramel, as stirring incorporates air, lowers the temperature, and inhibits proper browning. If you stir before the water evaporates, the syrup may crystallize. Plus, the caramel will adhere to the spoon, creating a mess.
Keep an eye on color
As the caramel darkens, the flavor intensifies. Pale golden caramel is mild, while deep amber caramel tastes rich with a hint of bitterness. As the mixture begins to darken, it's important to watch it carefully―it takes only seconds to go from perfect dark amber to overdone. If it cooks too long, it will appear almost black and have a bitter, burned smell and flavor. If that happens, you'll need to start over.
When caramel deepens to the desired shade of brown, remove it from the heat immediately and quickly continue with specific recipe instructions. If caramel is left in the pan too long, it can cool and begin to harden. If the caramel becomes too thick to pour, simply reheat it over low heat, swirling the pan occasionally until the mixture becomes liquid again.
Caramelizing vs. Maillard reactions
Although baked goods and meat develop a nutty, slightly sweet richness when browned, they're technically not caramelized, but undergo what is called "Maillard reactions." Named after the French chemist who identified the process in the early 1900s, Maillard reactions refer to the process of caramel-like flavor developing in foods as they brown. These reactions are similar to classic sugar caramelizing except they involve a series of complex reactions between proteins and sugars (rather than just sugar). Also, Maillard reactions occur at much lower heat than true sugar caramelization.
When your caramel reaches the perfect golden amber hue with a wisp of nutty aroma, you may be tempted to taste it. Don't. The molten caramel, which has been heated to about 340°, is too hot to touch or taste.
Other caramelized foods
Caramelizing is about more than just sugar. "Caramelized" is also a catchall culinary term for cooking foods other than sugar―most notably onions, but other vegetables and fruits, too―to a rich brown color and an intensified sweetness. Caramelized onions can be cooked to a sweet, caramel-brown, jamlike mixture. As onions sauté, their strong sulfur compounds dissolve and new compounds develop that are as sweet as sugar. Brussels sprouts also become sweeter as they brown, as cooking breaks down the cell structure and makes existing sugars more pronounced. In general, most vegetables that are naturally rich in sugars and low in acid―such as carrots, onions, and members of the cabbage family―lend themselves best to caramelizing.
The bottom line
The three most important elements to remember about caramelizing:
• Use a heavy, preferably light-colored pan.
• Once the sugar dissolves into the water, do not stir.
• Remove pan from heat immediately after caramel reaches the desired color.