I don't have any independant means of gauging caramelization, but according to Brewing Classic Styles "Caramelization is a sugar-to-sugar reaction that occurs at high temperatures and low moisture. (It does not happen during normal wort boiling.)"
According to Brewing Better Beer "Boiling the mash encourges the Maillard reaction, which creates Maillard products . . . Note that this is not the same as caramelization, a related process involving the melting and browning of sugar. The Maillard reacton involves amino acids (which contain nitrogen, coming from malt or proteins), reducing sugars, moisture, and heat. Sugars are corbohydrates and don't contain nitrogen."