Tomato, aroma formation

Although the number of aroma compounds derived from acyclic carotenoids is much inferior to that of the mono- and bicyclic compounds, some of them can also be considered as breakdown products from genuine mono-, sesqui- and diterpenoids. The importance of the aliphatic isoprenoids (282) to (291) in the formation of total flavors of certain foodstuffs is not less than that of the cyclic compounds, the three methyl ketones (282), (287) and (290) which are related to the main tomato pigment lycopene were observed in tomato flavor (75). The hexahydro derivative (291) from coffee (595), jasmine oil (722) and green tea 438) is perceived as flowery and warm and can be considered as an oxidative biodegradation product of phytol and phyta-diene. 6-Methyl-3,5-heptadien-2-one (283), with a grassy and cinnamonlike aroma 438) [detected in tomato 668), the essential oil of Hama-metis leaves 383), Ceylon tea (722) and passion fruit (777)], and pseudo-ionone (288) [also isolated from passion fruit (777)] are believed to be formed from two different dehydrolycopenes. Compounds other than carotenoids, such as solanesol or squalene, can also be considered... 

In tomato paste, for example (cf. Table 17.12), it was found that the changes in aroma caused by heating are primarily due to the formation of dimethylsulfide, methional, the furanones HD2F and HD3F and the increase in P-damascenone, and a substantial decrease in (Z)-3-hexenal and hexanal. 

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