Caramelizing

01How it works

Sugar alone — and not the Maillard reaction

Caramelization is pure sugar chemistry: no protein required. Most sugars start to break down around 320°F (160°C), though fructose goes earlier, near 230°F. As they break apart they rebuild into hundreds of new compounds — the colour, the nuttiness, the faint bitterness that balances the sweet.

This is not the Maillard reaction, even though both brown food. Maillard needs amino acids plus sugar and runs cooler, around 280–330°F. With onions you actually get both at once: their released sugars caramelize while their proteins brown through Maillard — which is exactly why “caramelized” onions taste deeply savoury, not just sweet.

02How to do it right

Low and patient — wet caramel forgives more

For sugar, there are two routes. Wet (sugar dissolved in a little water) is forgiving and even, less likely to scorch. Dry (sugar straight in the pan) is faster but uneven, because solid crystals are poor at passing heat between themselves. Once it is boiling, do not stir — agitation triggers crystallization. A scrupulously clean pan, and a touch of acid or corn syrup, keeps it from turning grainy.

For onions: medium-low heat, enough fat to coat the pan, a single layer, and real patience — 30 to 60 minutes. You cannot shortcut it with high heat; they will burn before they ever caramelize. Scrape up the fond as it forms; that is concentrated flavour.

03Common mistakes

Why it burned or turned to grit

• Heat too high. You get burnt and bitter, not caramel — the two are not the same thing.
• Stirring wet caramel. It seizes into sandy crystals. Fix: add a little warm water and gently remelt.
• Crowding the onions. They steam in their own water and never brown.
• Impatience. Cranking the heat to save time is the fastest way to bitter, scorched sugar.

→Recipes that caramelize