Abstract: The invention provides novel cyclopropene fatty acid compounds of formula (I) ##STR1## wherein R is a straight chain aliphatic group of 1 to 6 carbon atoms, n is an integer of from 10 to 15; Z is a hydrogen atom, or an alkyl group of 1 to 6 carbon atoms. Also provided is a method of producing lipids comprising cultivating a suitable lipid accumulating microorganism in a growth medium containing at least one cyclopropene fatty acid or its derivative of general formula ##STR2## wherein n is an integer greater than 8 and Z and R are as defined above, the CPFA acting as a desaturase inhibitor. At least one CPFA desaturase inhibitor may be introduced into a nitrogen limited growth medium for microorganisms in an amount such that when a suitable microorganism is cultivated in such a medium, one or more desaturase enzymes are inhibited so that higher levels of saturated or less saturated lipids may be produced which may be used in fat compositions as cocoa butter equivalents.