Keith, did you try the blind taste test yet? I am interested to know if it fixed the perfume character.
One of the things about 'lipids' is that it is all encompassing for all types of oils, fat and waxes, and includes fatty acids, sterols (phytosterols), triyglcerides, cholesterol and some vitamins. Basically, any generic compound that is (or partially) hydrophobic. In yeast, it includes the membrane bound phospholipids and the intracellular vitamins, sterols and free fatty acids. I imagine if you do a standard methanol:chloroform extra with hop pellets, they would test positive for 'lipids', as hops contain many hydrophobic compounds including oils, resins, sterols, alpha acids and beta acids. I think the hop oils should generically fall into the category of lipids, but I am not sure about the extent to which AA and BA are classified organically. I guess my point is that I think you can still get oxidation of lipids without yeast coughing up their guts. Oxidation of isomerized AA, or the often neglected BA, could easily occur while we oxygenate our wort prior to fermentation, or any point downstream. Additionally, no one discusses the 'plant' parts of hops which are loaded with phytoesterols (lipids) and consequently make their way into beer. If Fix is correct, then the soapy (perfumy) character of oxidized lipids could be coming solely from the hops.