Chapter 11
Aroma of Fresh Field Tomatoes Florian Mayer1, Gary Takeoka1, Ron Buttery1, Youngla Nam1, Michael Naim , Y a i r Bezman , and Haim Rabinowitch 2
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1Western Regional Research Center, Agricultural Research Service, U.S. Department of Agriculture, Albany, C A 94710 2Institute of Biochemistry, Food Science and Nutrition, Faculty of Agriculture, The Hebrew University of Jerusalem, P.O. Box 12, Rehovat 76-100, Israel
Although the flavor of tomatoes has been extensively studied over decades (1, 2, 3) it is not yet clear whether all odorants that are important contributors to fresh tomato aroma have been identified or whether the contribution of others has been overestimated. For the identification of the character impact odorants of fresh field tomatoes the method of aroma extract dilution analysis ( A E D A , 4) was applied to several different tomato cultivars. This resulted in finding 20 odorants with flavor dilution (FD)-factors larger than 1, which seem to contribute to the flavor of fresh tomato. Among these were (Z)-3-hexenal, hexanal, 1-penten-3-one, 2-phenylethanol, (E)-2-hexenal, phenylacetaldehyde and β-ionone, but also β-damascenone, 4-hydroxy-2,5-dmethyl-3-(2H)-furanone (Furaneol®), methional, 1-octen-3-one, guaiacol, (E,E)- and (E,Z)-2,4-decadienal and trans- and cis-4,5-epoxy-(E)2-decenal, some of which have been underestimated so far. One previously unknown flavor compound in fresh tomato aroma was identified as (Z)-1,5-octadien-3-one. Different methods of sample preparation were employed. Solvent assisted flavor evaporation (SAFE, 5) was found to be the most suitable method for the quantification of tomato odorants. The concentrations of all important odorants were determined in two different tomato cultivars and the odor units (ratio of the concentration of a flavor compound and its
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Cadwallader and Weenen; Freshness and Shelf Life of Foods ACS Symposium Series; American Chemical Society: Washington, DC, 2002.
145 odor threshold) were calculated. The biggest differences between the two cultivars were found in the concentrations and odor units of methional, phenylacetaldehyde, 1-penten3-one and 4-hydroxy-2,5-dimethyl-3-(2H)-furanone.
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Introduction The volatiles of fresh tomatoes have been investigated since the 1960s. About 400 compounds have been identified thus far (6). Not all of the volatiles actually contribute to the flavor of a product. The compounds that do contribute to fresh tomato flavor were first investigated in detail by Buttery and coworkers at the U . S. Department of Agriculture in the late 1980s and early 1990s. Buttery et al. identified 16 major contributors to fresh tomato aroma whose concentrations exceeded their odor thresholds (Table I, 7). Buttery and coworkers were able to simulate the aroma of fresh tomato by mixing 10 of those 16 odorants in the concentrations found in fresh tomato (Table II, 8). This model was very good and came very close to the aroma of fresh tomato, but still it was not perfect. In the late 90s other researchers investigated fresh tomato aroma. They applied the method of aroma extract dilution analysis ( A E D A , 4) and mentioned some additional odorants, which might be important contributors to fresh tomato aroma (2, 3). In contrast to Buttery (/, 7), Krumbein and Auerswald (2) found that compounds such as l-octen-3-one, methional, 4-hydroxy-2,5-dimethyl-3(2//)-furanone and (£,£)-2,4-decadienal had quite high flavor dilution (FD)-factors (Table III). Other compounds, i.e., 2-isobutylthiazole, 6-methyl-5-hepten-2-one and (Z)-3-hexenol, had only small Using the same method of A E D A , Guth and Grosch (3) found, apart from (Z)-3-hexenal, also acetic acid, methional, 4-hydroxy-2,5-dimethyl-3-(2//)furanone, eugenol and *r
