Organica

Current Biology 22, 1035–1039, June 5, 2012 ª2012 Elsevier Ltd All rights reserved

DOI 10.1016/j.cub.2012.04.016

Report The Chemical Interactions Underlying Tomato Flavor Preferences
Denise Tieman,1 Peter Bliss,1,9 Lauren M. McIntyre,2,3 Adilia Blandon-Ubeda,4 Dawn Bies,1 Asli Z. Odabasi,4 ´ Gustavo R. Rodrıguez,5 Esther van der Knaap,5 Mark G. Taylor,1 Charles Goulet,1 Melissa H.Mageroy,1 Derek J. Snyder,6 Thomas Colquhoun,7 Howard Moskowitz,4,8 David G. Clark,7 Charles Sims,4 Linda Bartoshuk,6 and Harry J. Klee1,* 1Horticultural Sciences Department, University of Florida, Gainesville, FL 32611-0690, USA 2Department of Molecular Genetics and Microbiology, University of Florida, Gainesville, FL 32610, USA 3Department of Statistics, University of Florida, Gainesville, FL 32611, USA4Food Science and Human Nutrition Department, University of Florida, Gainesville, FL 32611-0370, USA 5Department of Horticulture & Crop Science, Ohio Agricultural Research and Development Center, The Ohio State University, Wooster, OH 44691, USA 6College of Dentistry, University of Florida, Gainesville, FL 32611-0127, USA 7Department of Environmental Horticulture, University of Florida,Gainesville, FL 32611, USA 8Moskowitz Jacobs Inc., White Plains, NY 10604, USA Results and Discussion The Chemical Diversity within Tomato Varieties Tomato flavors are primarily generated by a diverse set of chemicals including sugars (glucose and fructose), acids (citrate, malate, and glutamate), and multiple, less well-defined volatiles [4]. Of the more than 400 volatiles that are detectable in fruits,only 16 were predicted to contribute to tomato flavor based on their concentrations in fruit and odor thresholds (odor units) [3]. To bring focus on which chemicals truly drive liking and to establish a molecular blueprint of tomato flavor, we assembled a chemical profile of 278 samples representing 152 heirloom varieties. These varieties mostly predate intensive breeding of modern commercial tomatoes[5]. Levels of glucose, fructose, citrate, malate, and 28 volatiles were determined, most over multiple seasons (see Table S1 available online). Molecular studies indicate that there is a relatively low rate of DNA sequence diversity within the cultivated tomato, Solanum lycopersicum [6], consistent with a genetic bottleneck associated with two periods of domestication in Central America and Europe[5]. It was therefore somewhat surprising that we observed variation in volatile contents of as much as 3,000-fold across the cultivars (Table 1). This unexpectedly large chemical diversity within the heirloom population provided an unprecedented opportunity to examine the interactions between sugars, acids, and volatiles with taste and olfaction. We conducted sensory analyses with a consumerpanel on a subset of the cultivars exhibiting the most chemical diversity. Panelists rated overall liking of each variety as well as the overall tomato flavor intensity, sweetness, and sourness on sensory and hedonic versions of the general labeled magnitude scale (gLMS) [7, 8]. Thirteen panels rated 66 different cultivars as well as supermarket-purchased varieties over three seasons (Figure 1; TableS2). Several cultivars were repeated in multiple seasons. Random samples of each set were removed for chemical analysis with the number of measured chemical attributes expanded to 68 (Table S2). Despite its popularity and important contribution to human nutrition, the commercially produced tomato is widely viewed as having poor taste, and its flavor is a major source of consumer dissatisfaction. Incontrast, there is a public perception that the term ‘‘heirloom’’ indicates great taste. Our results indicate that this is not always the case. Some heirlooms received liking scores well below those of supermarket-purchased tomatoes (Table S2). Our results with respect to supermarket tomatoes present an interesting contrast. They were highly variable even within a single season, possibly...