2009_Book_FoodChemistry

3.7 Changes in Acyl Lipids of Food 223
(3.96)
The side chains of the resultant tetra-substituted
cyclohexene derivatives are shortened by oxidation
to oxo, hydroxy or carboxyl groups.
In addition, the cyclohexene ring is readily
dehydrogenated to an aromatic ring, hence compounds
related to benzoic acid can be formed.
The fatty acid or triacylglycerol radicals formed
by H-abstraction in the absence of oxygen can
dimerize and then form a ring structure:
Fig. 3.38. Autoxidation of saturated fatty acids.
Hypothetical reactions involved in formation of volatile
aldehydes
3.7.4.2 Polymerization
Under deep frying conditions, the isolenic
fatty acids are isomerized into conjugated
fatty acids which in turn interact by a 1,4-
cycloaddition, yielding so-called Diels–Alder
adducts (cf. Reaction 3.96).
(3.97)
On the other hand, polymers with ether and
peroxide linkages are formed in the presence of
oxygen. They also may contain hydroxy, oxo or
epoxy groups. The following structures, among
others, have been identified: