|Buttery, Ron G|
Submitted to: American Chemical Society Symposium Series
Publication Type: Proceedings
Publication Acceptance Date: 2/3/2003
Publication Date: 1/10/2004
Citation: Mayer, F., Takeoka, G.R., Buttery, R., Whitehand, L.C. 2004. Differences in the aroma of selected fresh tomato cultivars. ACS Symposium Series Chapter 13. p. 189-206. Interpretive Summary: The tomato is the second largest vegetable crop in dollar value in the U.S. with a fresh market production value of $1.16 billion in 2000. The U.S. produced 3.77 billion lbs. of fresh market tomatoes in 2000. In the 1950s tomato yields were relatively low (8,900 lbs. per acre in 1955 vs. 30,600 lbs. per acre in 2000) and shelf-life was very short. Advances in agrotechniques, genetics and breeding have led to dramatic increases in both yield and shelf-life. The latter resulted from the introduction of ripening inhibitor genes that adversely affect the flavor. Consumers have been complaining about the lack of flavor in commercially available fresh tomatoes for several years now. One well-known reason is that many tomatoes are harvested green and induced to ripen by the use of ethylene prior to marketing. Although sensory characteristics such as color, texture and sugar-acid content are important factors in consumer acceptance, the aroma content is considered a major quality trait for which a batch of tomatoes will be accepted or rejected. We determined the flavor profiles and the concentrations of the most important contributors to fresh tomato aroma in two highly accepted (BR-139 and FA-624) and two less accepted (R 144 and R 175) tomato cultivars. Simulation of the odor of the selected tomato cultivars by preparation of aroma models and comparison with the corresponding real samples confirmed that all important fresh tomato odorants were identified, their concentrations were determined correctly in all four cultivars and that differences in concentration make it possible to distinguish between the different cultivars and were responsible for the differences in preference.
Technical Abstract: Two highly preferred (BR-139 and FA-624) and two less preferred (R 144 and R 175) fresh tomato cultivars, which significantly differ in their flavor profiles, were analyzed for their volatile flavor composition using Aroma Extract Dilution Analysis (AEDA). Based on AEDA results, 19 odorants were selected for quantification by gas chromatography/mass spectrometry (GC/MS). Odor Units (ratio of the concentration of an odorant in the food and its odor threshold) were calculated for all odorants in each tomato cultivar and compared between the more and less preferred cultivars for differences. In the more preferred cultivars, compounds such as (E,E)- and (E,Z)-2,4-decadienal and 4-hydroxy-2,5-dimethyl-3(2H)-furanone (Furaneol®) had higher odor units, while in the less preferred cultivars phenylacetaldehyde, 2-phenylethanol or 2-isobutylthiazole had higher odor units. Simulation of the odor of the selected tomato cultivars by preparation of aroma models and comparison with the corresponding real samples confirmed that all important fresh tomato odorants were identified, their concentrations were determined correctly in all four cultivars and that differences in concentration, especially of the compounds mentioned above, make it possible to distinguish between the different cultivars and were responsible for the differences in preference. Sensory and statistical evaluations revealed no major differences in odor between the aroma models and the corresponding real tomato samples.