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What Is Caramelization?
Caramelization is a slow cooking process that occurs when sugar is cooked over low heat, causing a change in both appearance and flavor. Through a process called pyrolysis, during caramelization, the sugar in a food oxidizes, taking on a brown color and a rich, slightly sweet and nutty flavor.
Although the effect of caramelization is similar to the Maillard reaction—a chemical reaction during cooking that gives food a browned flavor—the two are distinct processes. While the Maillard browning reaction occurs when enzymes and amino acids in certain ingredients are subjected to high heat, caramelization is simply the breakdown of sugar molecules at a high temperature.
The Caramelization Process on a Molecular Level
During caramelization reactions, high dry heat causes the sugar to break down, releasing volatile chemicals that create that signature caramel flavor. The carbohydrates—aka the sugars found in starches—also take on a deeper color during this process, ranging from golden to deep brown depending on the type of sugar, temperature, and cook time.
The sugars begin to melt, foam, and lose water through condensation, reacting with the other sugar molecules to create flavorful new compounds. After the sugar has begun to condensate, an isomerization of aldoses to ketoses occurs, leading to the final reactions: fragmentation reactions (which create flavor) and polymerization reactions (which create color). The signature golden brown color created by caramelization is produced by three polymer groups: caramelans (C24H36O18), caramlens (C36H50O25), and caramelins (C125H188O80).
Caramelization Temperatures of Sugars
Depending on the types of sugars contained in an ingredient, the temperature at which the caramelization process begins varies. The temperatures at which each sugar begins to caramelize are:
- Sucrose - 320° F
- Fructose - 230° F
- Glucose - 320° F
- Galactose - 320° F
- Lactose - 397° F
7 Caramelization Stages of Sugar
As pure sugar is cooked down through the caramelization process, it takes on different flavors, consistencies, and levels of sweetness with each step. This is a result of the amount of water left in the sugar at any point during cooking—the less water there is, the more concentrated the sugar will be.
The 7 stages of the caramelization process are:
- Thread Stage - At 215–230° F, the sugar will form thin threads, which can be used to make preserves and syrups.
- Soft Ball Stage - At 240° F, the sugar forms a soft ball that can be flattened and molded into fudge, fondant, pralines, and caramel candies.
- Firm Ball Stage - At 245° F, the sugar solidifies further into a more firm, sturdy ball, which is used to make marshmallows, meringues, gummies, and toffee.
- Hard Ball Stage - At 250–260° F, the sugar has been formed into a hard ball that holds its shape, used to make nougat, toffee, and butterscotch.
- Soft Crack Stage - At 270–290° F, the sugar will form pliable but firm threads, which can be stretched into chewier candies like nougat, butterscotch, and taffy.
- Hard Crack Stage - At 300–310° F, the sugar has hardened into brittle, fragile threads, which are used to create hard candy, candy brittle, and glazed fruits.
- Caramel Stage - At 320–360° F, the caramelization will be complete, and the sugar will have changed in color and flavor.
Culinary Uses for Caramelized Sugar
Caramelized sugar is a key aspect in many of the world’s favorite sweet confections, including marshmallows, fudge, syrup, brittle, butterscotch, meringue, taffy, nougat, toffee, caramel candies, and caramel topping. These uses of caramelized sugar can be consumed on their own or used to accentuate a variety of sweet recipes, like crème brûlée, dulce de leche, and caramel sauce for ice cream and other treats.
11 Caramelized Food Ideas
Caramelization can take place in any food that contains carbohydrates. These carbohydrates can come in numerous forms, from the natural sugars in fruits and vegetables, to more processed sugars like table sugar. Fruits and vegetables are a common choice for caramelization, thanks to their natural sugar content.
- Onions: Caramelizing onions transforms this astringent vegetable into a subtly sweet, complex addition to savory dishes (try yellow onions, white onions, or red onions). Caramelize onions in olive oil for French onion soup, grilled cheese, savory tarts and quiche, vegetable stock, caramelized-onion dip, pasta sauces, and burgers.
- Apples: Caramel apples are one thing, but caramelized apples make a versatile sauce that can be spiced up with warm fall spices or left natural and poured over waffles, ice cream, or cheesecake.
- Bananas: Bananas caramelized in butter make up the show-stopping sauce in the ice cream dessert bananas foster.
- Figs: Caramelize figs in balsamic vinegar and serve them as an appetizer with goat cheese or as a dessert with panna cotta or ice cream.
- Pineapple: Grill pineapple a caramel-y sweet addition to burgers or baked in the bottom of the pan for a pineapple upside-down cake.
- Peaches: Caramelize halved peaches on the grill and toss into a summer salad or serve with ice cream.
- Potatoes: Caramelized potatoes make a luscious side dish fit for any holiday meal.
- Endives: If making Chef Thomas Keller's Pan-Roasted Duck Breast, caramelize endives in the leftover duck fat before plating.
- Pecans: No ice cream sundae is complete without pecans caramelized in butter and brown sugar.
- Carrots: Carrots' high sugar content make them ideal for caramelizing, a step that elevates the simplest side dish.
- Bacon: Dust bacon in brown sugar or maple syrup before cooking in a cast-iron skillet to caramelize the crispy edges.