Why does the upper aqueous phase look pinkish when purifying RNA from fatty tissue?

This can occur if there is too much sample, which will affect the phase separation. Additionally, with extremely fatty samples, there is a layer of fat on top of the homogenate which should be removed before adding chloroform.  If chloroform has already been added, increasing the chloroform followed by vigorous shaking and centrifugation should help localize the fat into the organic phase.