Table 1.

The main volatiles derived from lipids contributing to off−flavors.

No.	Off−Flavors	Origin	Oxidation Causes	Refs.
1	1−Penten−3−ol	Eicosapentaenoic acid	15−Lipoxygenase	[13]
2	(E)−2−Pentenal	Linolenic acid, docosahexaenoic acid /n−3 polyunsaturated fatty acids	15−Lipoxygenase	[42]
3	Hexanal	Linoleic acid /n−6 Polyunsaturated fatty acids	15−Lipoxygenase/autoxidation	[43,44]
4	(E)−3−Hexen−1−ol	Eicosapentaenoic acid	15−Lipoxygenase	[13]
5	(E)−2−Hexenal	Linolenic acid /n−3 polyunsaturated fatty acids	15−Lipoxygenase	[13,42]
6	Heptanal	n−6 Polyunsaturated fatty acids	Autoxidation	[42,43,44]
7	1−Octen−3−ol	Arachidonic acid, linoleic acid /n−6 polyunsaturated fatty acids	12−Lipoxygenase	[42,44]
8	(Z)−1,5−Octadien−3−one	Eicosapentaenoic acid /n−3 polyunsaturated fatty acids	12−Lipoxygenase	[13,43]
9	Nonanal	n−9 Polyunsaturated fatty acids	12−Lipoxygenase	[42,43]
10	(E)−2−Nonenal	Linoleic acid, arachidonic acid	12−Lipoxygenase	[43]
11	(E,Z)−2,6−Nonadienal	Eicosapentaenoic acid /n−3 polyunsaturated fatty acids	12−Lipoxygenase	[13,43]
12	2,4−Heptadienal (two isomers)	Linolenic acid /n−3 polyunsaturated fatty acids	12−Lipoxygenase/autoxidation	[43]
13	2,4−Decadienal (two isomers)	Linoleic acid	Autoxidation	[45]
14	Short− and branched−chain fatty acids (e.g., butanoic, 2−/3−methylbutanoic, hexanoic, and octanoic acids)	Fatty acids	Autoxidation	[46]