In natural environments, only the tridecanone isomer with the carbonyl group in position 2 has been found to exist. Tridecan-2-one occurs as a flavor component in many raw materials originating from plants or animals, and is produced in multi-step oxidative enzymatic transformations of fatty acids present in them. The presence of tridecan-2-one has been well documented in milk and its products, e.g. in the concentrate of albumen, yogurt, butter and the Italian cheese Grana Padano. Boiled pork liver is also a source of this ketone. Tridecan-2-one is present in hop and in a few exotic plants that grow in equatorial or tropic climates. The primary sources of tridecanones and their derivatives are as follows:
• The essential oil from the roots of the plant Bowdichia virgilioides (Leguminosae) containing ca. 55 percent tridecan-2-one.
• The essential oil from fresh fruits, flowers and bark of the plant Litsea monopelata (Roxb.) containing 11.3 percent tridecanol and 9.4 percent tridecanal.
We recently studied a group of compounds derived from tridecan-7-one and determined their odor characteristics and threshold concentration.6 It was discovered that tridecan-7-one and its ethylene acetal have interesting, pleasant nutritive odors. The odors of tridecan-7-ol and its acetate are less interesting — waxy-fatty.