I should have checked my library before responding, but better late than never. Here is a quote from Yeast, by Chris White and Jamil Zainasheff, p. 114:
As far as yeast activity goes, crashing the temperature or lowering it slowly makes little flavor difference if you are dropping the beer below 40 F (4 C). However, a very rapid reduction in temperature (less than 6 hours) at the end of fermentation can cause the yeast to excrete more ester compounds instead of retaining them. In addition, if you plan to use the yeast for repitching, you should avoid rapid temperature changes (up or down), as they can cause the yeast to express heat shock proteins
No mention of lipids, only esters.