That’s what reader OB wants to know. Most authorities will tell you, OB, that sucrose caramelizes at 340 degrees Fahrenheit (170 degrees Celsius). That’s true, but then there are some mitigating factors that make the precise caramelization point of table sugar a rather hard thing to pin down. That’s why I generally write “above 300 degrees Fahrenheit” because it’s a safe thing to say. 320 degrees Fahrenheit (160 C) is about the point you usually start to see the first bit of yellowing in the pan. That’s caramelization. But what is going on then if sucrose doesn’t caramelize until 340?
The answer is that when the temperature reaches 320, sucrose isn’t the only sugar you have in the pan anymore. I know what you’re thinking: how the heck did other sugars get in there? The answer is that some of the double-sugar sucrose molecules have now split into their component parts: single-sugar glucose and fructose molecules — and they both have lower caramelization points (300 degrees Fahrenheit (150 C) and 220 degrees Fahrenheit (105 C) respectively).
These are the sugars that are starting to take on color early. By the time you reach 340 any remaining sucrose is starting to caramelize and darkening really starts to accelerate, so much so that by 350 you’d better be planning on stopping the cooking with cream or butter or the whole thing will turn to a sticky ash-tasting mass.
So I hope you sort of see what I mean here, OB. The caramelization point of table sugar is rather fuzzy. I hope that’s not too frustrating an answer!