The Flavor of Tomatoes

by Kirke on September 27, 2016

 

Once again nature is blessing us with a glorious tomato season, which lasts from August to mid-November (if we’re lucky) here on the West Coast. It wasn’t too long ago that the only great tomatoes you could find, even at the peak of season, were from a back yard garden, or those found at the Farmer’s Market. Now heirloom tomatoes can be found at any decent size grocery store in California, even all year round, presumably the product of Latin America or hot house agriculture. I’ll confess to have fallen prey to the tempting allure of what looks like a perfect large heirloom tomato in February. I am always disappointed by a mushy texture and a shallow watery flavor profile. The sad part of this new ubiquitous tomato availability, is that something that was once rare and special has become common and pedestrian, often even in the peak of the season. As any true devotee of California Cuisine will testify, the maxim of eating a food at the peak of its season when it is as good as it ever will be, is as true as it ever was.

something that was once rare and special has become common and pedestrian

But at the peak of tomato season 2016, this chef is finding it difficult to find a well-tended (not refrigerated), vine-ripened, heirloom tomato at any grocery store, including the one where you would Wholly (hint, hint) expect to seasonally supply (they refrigerate tomatoes). My local Farmer’s Market is the only reliable source for great tomatoes this season. Ever since I was a little boy holding onto mommy’s apron strings, I have always known you do not refrigerate a tomato unless it has become overripe or cut open because it ruins the texture and flavor. This is problematical for the grower, grocer and consumer. The reason commercials have always touted ‘vine-ripened tomatoes’ is that a tomato needs every last molecule of the carbohydrates, proteins, and minerals the vine of a tomato plant can deliver to the fruit in order to present for our enjoyment the over 400 volatile aromas and flavors that make the tomato such an ethereal pleasure. But if a grower really does ripen his tomatoes on the vine, the shelf-life will be very short, leaving little time to turn his harvest into cash.

 

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The dilemma has led to a number of scientific studies trying to determine how to preserve the flavor qualities while lengthening the shelf life of the tomato fruit. (More on shelf life later.) One study that seemed to provoke interest sought to identify which of the myriad of chemicals that make up a tomato’s flavor profile were principally responsible for that certain something the perfect tomato possesses. Published in Current Biology in 2012, the research paper “The Chemical Interactions Underlying Tomato Flavor Preferences” from principle author Harry J. Klee of the University of Florida found an encyclopedia of molecules in his tomatoes, and then segregated a few key contributing flavor generators. After isolating 70 chemicals from 278 samples of 152 heirloom varieties of tomato, 170 tomato tasters rated how much they liked what they were eating. The resulting large number and variation of chemicals effecting flavor profiles caught researchers by surprise. More surprising was how few of the tested volatiles had an impact on consumer liking.

 

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I’d like to offer a word of caution to Mr. Klee et al. regarding their attempt to isolate all the components of an heirloom tomato’s flavor profile. They mention that one of chemicals was thought to be an important contributor to flavor even though it had a low reported odor threshold, and that this and other “ should not be considered as high-priority targets for genetic manipulations.” One thing I learned as a working chef, improvising a soup of the day many times each week, and that is the magical effect of adding minuscule quantities of different ingredients. I’m taking about a few drops or dashes of flavorings, 1 tsp. per 5 gallons, for example. Sometimes a vinegar, sometimes a tiny suggestion of tamari. Not enough to obviously perceive and identify. The result is simply complexity unknowingly perceived. This is why I feel that attempts to reduce the 400 volatile aromas found in heirloom tomatoes to a couple of dozen that can be genetically repackaged will fail to produce the ethereal experience we all expect when consuming a true, garden fresh, vine-ripened tomato. It’s those aromas under the odor threshold that make for the wonderful complexity we perceive in a good tomato.

Tomato Guts

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I hope that the magic of what makes a peak of the season tomato is never revealed. I don’t want to meet the man behind the curtain. The following graphic from Mr Klee’s research paper accidentally illustrates my point perfectly.

Cluster Analysis of Tomato Varieties Sorted by Flavor Chemical Composition

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This graphic utilizes JMP software which analyzes statistical data. In this case it is comparing varieties of tomatoes on the right, taste tested over multiple seasons, 70 chemical attributes listed across the bottom, and test liking scores on the left. The results show “the chemical complexity of liking, as there is no simple pattern of chemical content that separates high from low consumer liking scores.” I think the image is perfect! It is like a pointillist representation of the unmeasurable delight of tasting the perfect vine-ripened tomato. Bite into such a tomato, close your eyes, roll the pulp in your mouth, let the perfumed volatiles rise behind your palate, and savor the flavors through retronasal olfaction (you know, taste the tomato). The image above is visualization of that sensation, representing the full spectrum of flavors that can’t, and I have firmly decided, shouldn’t be parsed. Somethings are best left unexplained. Once you are shown how to perform a magic trick the wonder disappears. Maybe it’s okay that we only experience the perfect tomato once a year when its season comes around. The restriction enhances the enjoyment.

 

                           The Tomato I Just Ate

 

On top of having to wait for the tomato season each year, we must also deal with its perishability. A true vine-ripened tomato typically has a shelf life of only 48 hours. According to one study, “storing tomatoes at 4°C (40°F) degrees induces a drastic loss in volatiles. After 30 days at 4°C, the concentration of volatiles had decreased by 66%. Reconditioning for 24 h at 20°C (68°F) was able to recover some aroma production.” They go on to claim that after refrigeration the texture loss is acceptable, but why risk it?! I shop for tomatoes at the Farmer’s Market every Saturday, and find most survive the week. If they start getting too soft, I pop them in the fridge and use them peeled and seeded for sauce. That works for me, and it should work for you, too.

If you live in a cooler clime, I imagine the local tomato season is over for most of you by now. In California our first tomatoes arrive in August, but you might find a tomato salad at our Thanksgiving tables. Don’t worry, tomatoes will come around again. Can’t wait until next year.

 

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References:

Tieman, D., Bliss, P., McIntyre, L. M., Blandon-Ubeda, A., Bies, D., Odabasi, A. Z., & Klee, H. J.(2012). The chemical interactions underlying tomato flavor preferences. Current Biology, 22, 1035-1039. http://dx.doi.org/10.1016/j.cub.2012.04.016

Cell Press. (2012, May 24). The secret to good tomato chemistry. ScienceDaily. Retrieved September 21, 2016 from www.sciencedaily.com/releases/2012/05/120524123015.htm

Renard, C. M., Ginies, C., Gouble, B., Bureau, S., & Causse, M. (2013). Home conservation strategies for tomato (Solanum lycopersicum): Storage temperature vs. duration– is there a compromise for better aroma preservation [Abstract]. Food Chemistry, 139(1-4), 825-836. http://dx.doi.org/10.1016/j.foodchem.2013.01.038

 

 

 

 

 

 

 

Leave a Comment

{ 2 comments… read them below or add one }

Leslie September 28, 2016 at 5:29 pm

This makes me hungry for tomatoes right now! I’ve been enjoying the tomatoes my neighbor grows that she’s kind enough to share. But the weather has changed…I’ll have to wait for next summer.

Reply

Kirke October 4, 2016 at 1:17 pm

Summer pleasures are fleeting! Stay warm dreaming of next season’s tomato delights, and in the meantime enjoy some cruciferous vegetables. Thanks for your comment.

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