Explanation:

In the most common type of flame, hydrocarbon flames, the most important factor determining color is oxygen supply and the extent of fuel-oxygen pre-mixing, which determines the rate of combustion and thus the temperature and reaction paths, thereby producing different color hues.

Different flame types of a Bunsen burner depend on oxygen supply. In the diagram above, on the left a rich fuel with no premixed oxygen produces a yellow sooty diffusion flame; but on the right a lean fully oxygen premixed flame produces no soot and the flame color blue.

The same thing happens in a candle and a stove