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See Inside Scientific American Volume 308, Issue 5

Scientists Are Trying to Get Supermarket Tomatoes’ Flavor to Catch Up

Trying to return tomatoes to their salad days
microscope, canned food



Matt Collins

The Martian Giant is not a big dude discovered by the Curiosity rover. The Mexico Midget is not the most popular wrestler south of the Rio Grande. The Three Sisters is not the title of a play by Anton Chekhov. Well, actually, it is, but that's not this Three Sisters. This Three Sisters—like the Martian Giant and the Mexico Midget—is a tomato.

All are varieties of heirloom tomatoes being crushed, pureed, ground up and analyzed in a noble and flavorful quest. As per the title of a session at the Annual Meeting of the American Association for the Advancement of Science in Boston in February, they are doing their part in “Fixing the Broken Tomato.”

Indeed, the industrial, three-in-a-cellophane-wrapped-pack tomato stinks. Everybody knows it, and everybody has known it for decades. “The loss of flavor probably coincides with the period of really intensive breeding that started at the end of World War II,” said session speaker Harry J. Klee, who works in the horticultural sciences department and the plant molecular and cellular biology program at the University of Florida. “I've got this great article from the New Yorker magazine that [asks] what's wrong with our tomatoes. It's from 1977. So in the 1970s we already knew this was a problem.”

The modern supermarket tomato became damaged goods as part of the attempt to keep it from becoming damaged goods. In the pursuit of a storable, transportable tomato, appearance, firmness and shelf life all trumped taste. Another big driver was having more spheroids per stalk: “Modern tomatoes focus on yields, basically making too many fruit at same time,” Klee said. “The plant can't keep up with filling those fruits with nutrients. So the effect of what the modern breeders have done is basically to take the old tomatoes and add water.”

You might assume that making a tomato that ships well and lasts forever but tastes like cardboard would be a bad business model, like bus drivers sticking to timetables by not stopping to pick up passengers. But that assumption is based on the notion that the tomato eater is the customer. “The customer of the breeders is the grower, not the consumer,” Klee said. “Growers want what will make them money, not what people want. And breeders typically do not interact with the people who tell them what they think of the final product,” by, for example, letting half-masticated messages fall from their mouths.

Shipping often involves refrigeration, which kills whatever flavor is left by wiping out what are called volatiles—odoriferous chemical compounds that go up the nose and influence the perception of taste. “By and large,” Klee said, “the postharvest system is set up to destroy flavor.”

Clearly, one way to address our bad tomatoes would be to reform the entire industrial agricultural system. Rather than breeding the flying pigs that would signal that development, Klee is simply trying to reverse engineer the tomato.

He and Linda M. Bartoshuk, a taste-and-smell researcher at the University of Florida who also spoke at the session, start with dozens of varieties of heirloom tomatoes of old lineages, such as the aforementioned Martian Giant et al. A panel of taste testers rate the tomatoes. Then the research team pulverizes them (the tomatoes, not the taste judges), somehow resists the urge to ladle the resulting sauce over linguine and analyzes the produce's makeup.

Klee and Bartoshuk have found six specific volatile compounds that enhance sweetness—which turns out to be the single most important factor in people's ratings of tomatoes—and two volatiles that suppress sweetness. These volatiles can really fool the brain. A variety of tomato called the Matina is rated twice as sweet as one called Yellow Jelly Bean, despite having less sugar. “If we look at those six volatiles that enhance sweetness,” Bartoshuk said, “the Matina has all of them in higher concentrations than the Yellow Jelly Bean.” What's in a name? Indeed.

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