Tomato volatiles

The central question that I want to approach here is the possible relationship between flavor preferences and nutritional value. There are a lot of data to work with. More than 70(X) volatile flavor substances have been identilied in foods and beverages. The situation may not be quite as complex as this would suggest. While it is true that any single fruit or vegetable may synthesize a few hundred volatile compounds, only a modest subset of these will contribute to its flavor profile. So the task is to sort out what these are, identify their sources, and link, where possible, these sources to nutritional value. Studies with the tomato provide a great example. The bottom line is Virtually all of the major tomato volatiles can be linked to compounds providing health benefits to humans. ... 

Souchon et al. [41] found this process to be very efficient in the recovery of tomato volatiles both from the model system and from commercial tomato waste stream. They reported that using a 1.4-m membrane surface, a 20-L/h waste stream flow, and hexane as the extracting solvent, they would recover approximately 95% of the hydrophobic tomato volatiles. Volatile recovery is dependent upon the type of volatile being extracted and the extracting solvent. 

Linforth, R.S.T., Savary, I., and Taylor, A.J. 1994. Profile of tomato volatiles during eating. In Trends in Flavour Research (H. Maarse and D.G. van der Heij, eds.) pp. 65-68. Elsevier Science, Amsterdam. 

Studies to develop and apply quantitative methods to the analysis of fresh tomato volatiles have been recently carried out by some of the authors (J.,2). Besides the known major compounds a number of compounds were detected In the gas liquid chromatography (GLC) analysis which had spectral data unlike that of any of the 400 compounds previously reported as tomato volatiles (cf. 3 ). As these compounds occurred In reasonable amounts In fresh tomato It seemed necessary to determine their Identities In order to give a satisfactory quantitative picture of fresh tomato volatiles. It also seemed desirable to determine the odor threshold of these compounds to have a better understanding of their probable contribution to tomato aroma. 

Three main approaches were applied to fresh tomatoes. The first approach was a qualitative one. It was aimed at the further identification of important aroma compounds. The second approach was designed to develop better methods for the quantitative analysis of important tomato aroma compounds and to apply the methods to various samples of tomatoes. The third approach involved the sensory evaluation of identified tomato volatiles to determine their probable importance to fresh tomato aroma. 

The identification of 1-nitro-3-methylbutane in tomato had been reported previously by Wobben et al. (5) although they had not published any GLC or mass spectral data. None of the other numerous studies of tomato volatiles (of. 3.) had reported finding this compound. It is a relatively prominent component of fresh tomato occurring at a concentration as much as 200 ppb in some varieties such as Ace and related varieties but in other varieties it occurs at lower levels (10-50 ppb). However, it does not seem to be important to fresh tomato aroma because it is a relatively weak odorant with an odor threshold of 150 ppb. 

Studies with model systems of standard solutions of components in water using the same isolation procedure outlined by the authors for the tomato (2) showed satisfactory recoveries of most tomato volatiles. A few compounds gave unacceptable recoveries for the 1 hour sweeping period used. These were 2-phenylethanol which gave a 3 recovery (relative to anethole) and eugenol which gave a 0.55S recovery (relative to anethole) for the 1 hour sweep period. ... 

Stone, E. J., Hall, R. M. and Kazeniac, S. J. "Precursors of Tomato Volatiles". Paper presented 162nd National Meeting, American Chemical Society, Washington, D.C. 1971. 

Tomato volatiles are important to both aroma and flavor and their concentration increases with ripening (1061. Because many of the volatile aroma compounds of tomatoes apparently result from enzymatic breakdown of carotene pigments (1071. CA, which delays pigment synthesis, can be expected to delay volatile production. 

Xu Y Barringer S. Comparison of tomatillo and tomato volatile compounds in the head-space by selected ion flow fube mass speetrometiy (SIFT-MS). J Food Sci. 2010 75 C268-C73. 

No single molecule has a fresh tomato smell, but (Z)-3-hexenal makes the greatest molecular contribution to the tomato volatiles. ( )-2-hexenal and hexyl acetate are chief among molecules responsible for the freshness of apple juice flavor, and thus hexenals can be used as additives to make flavors have a greener edge to them. 

RG Buttery, R Teranishi, RA Flath, LC Ling. Fresh tomato volatiles. In R Teranishi, RG Buttery, F Shahidi, eds. Flavor Chemistry, Trends and Developments. ACS Symposium Series No. 388. Washington, DC American Chemical Society, 1989, pp 213-222. 

Farneti, B., Cristescu, S. M., Costa, G. et al. (2012) Rapid tomato volatile profiling by using proton-transfer reaction mass spectrometry (PTR-MS). J. Food Sci. 55, C551. 

Dynamic headspace using Tenax TA. A sample of 500 g of tomato plus 500 mL of saturated calcium chloride solution and an internal standard (2-octanone) were mixed in a blender. The mixture was placed in a 3-L flask. The flask was purged with purified air while the tomato mixture was stirred with a magnetic stirrer the tomato volatiles in the air stream were passed through a 200-mg Tenax trap. The isolation was carried out for 150 min, then the trap was removed and the volatiles extracted with 3 mL of acetone. Samples were concentrated under nitrogen to a volume of 50 pL. 

The chromatograms of tomato volatiles obtained by the three methods are shown in Fig. 3. SPME was unable to detect the highly volatile flavor components l-penten-3-one and 3-methyl butanol. All important aroma volatiles were detected by liquid-liquid extraction. Phenylacetaldehyde and 2-phenylethanol were... 

Figure 3 GC/MS chromatograms of tomato volatiles obtained by three different sample preparation techniques (A) dynamic headspace on Tenax (B) headspace SPME (PDMS) and (C) Freon liquid-liquid extraction. Peak identification is as follows (1) 3-methylbuta-nal (2) l-penten-3-one (3) hexanal (4) (Z)-3-hexenal (5) 2-methyl butanol (6) (E)-2-hexenal (7) ( )-2-heptenal (8) 6-methyl-5-hepten-2-one (9) (Z)-3-hexenol (10) 2-isobu-tylthiazole (11) phenylacetaldehyde (12) methyl salicylate (13) geranylacetone (14) 2-phenylethanol (15) 3-ionone (IS) 2-octanone internal standard.

---