Question

does the glucose burns at low temperatures why​

Answer 1

Answer:

There is burning, as in turning brown to black in a pan, and then there is burning, as in a fire.

I was surprised how difficult it is to find the autoignition temperature for sucrose. Many other substances are listed but not this common ingredient. I think it’s because, “it depends”. There is no single value, or even a meaningful range. A small particle size (eg. powdered sugar or crystalline sugar with a percentage of dust in it) and higher oxygen pressure (at low altitudes) lowers the temperature hugely compared to, say, a pan of syrup left on the stovetop to dry out and burn. My wife ran the latter experiment (she was making hummingbird food) and filled the house with smoke, but there was no actual flame that I know of.

Here’s a fun experiment you can run for yourself. Turn on your stove burner. If it’s electric, wait for it to approach red-hot. Grab a pinch of sugar and toss it directly on the burner. You should see a tiny fireworks display as the sugar burns. You’ll also get that distinct smell of cooked sugar. I haven’t done this for a long time, but my recollection is that the burner needs to be fairly hot. Low to medium won’t do it.

Explanation: