Is the missing ultra-red material colorless ice?

The extremely red colors of some transneptunian objects and Centaurs are not seen among the Jupiter family comets which Supposedly derive from them. Could this mismatch result from sublimation loss of colorless ice? Radiative transfer models show that mixtures of volatile ice and non-volatile organics could be extremely red, but become progressively darker and less red as the ice sublimates away. (C) 2008 Elsevier Inc. All rights reserved.