a different color flame, will indicate the different levels of oxygen intake of the flame. when the flame is blue, it indicates that the flame has a very low amount of O2 in the gas which is trying to burn. And when the flame is RED, means that there is more oxygen available when it is burnt.
Blue is in a flame because of light and temperature. Blue flames are hotter than other flame colors due to a more complete combustion that helps the gas molecules ionize. This causes them to appear blue.