David Manning for The New York Times
Heirloom tomatoes grow in a greenhouse at the University of Florida.
GAINESVILLE, Fla. — Science is trying to build a better supermarket tomato.
At a laboratory here at the University of Florida's Institute for Plant Innovation, researchers chop tomatoes from nearby greenhouses and plop them into glass tubes to extract flavor compounds — the essence of tomato, so to speak. These flavor compounds are identified and quantified by machine. People taste and rate the hybrid tomatoes grown in the university's fields.
"I'm 98 percent confident we can make a tomato that tastes substantially better," said Harry J. Klee, a professor of horticultural sciences. He hopes that the fruits of his labor will be available to commercial growers within four or five years and in supermarkets a couple of years after that. He thinks he can make seeds for better tomatoes available to home gardeners even sooner, within a year or two.
The insipid-tomato problem is well known both to salad lovers and scientists. For example, a gene mutation that tomato breeders love because it turns the fruit a luscious red also happens to make it blander. Refrigeration, transportation and other factors also take their toll. Over the decades, the average tomato has become not only less tasty but less nutritious.
Enter Dr. Klee, who helped found the Institute for Plant Innovation a decade ago and has been in a quest for a more flavorful and nutritious mass-market tomato ever since.
It is easy to find a better tasting and more nutritious tomato. Go to a farmer's market or grow one in the backyard. It is also easy to breed a plant that produces something tastier than a supermarket tomato — cross a sweet heirloom with the supermarket variety. In the greenhouse, Dr. Klee pulls one such hybrid tomato off a vine, and it does taste sweeter. But a hybrid also loses some of the qualities highly valued by commercial growers — it is not as fecund, not as resistant to disease, not as easily grown, not as pretty.
As growers are paid by the pound, a better-tasting but less productive tomato holds little economic appeal, and thus was the supermarket tomato doomed to blandness.
Dr. Klee's goal is to tweak the tomato DNA — through traditional breeding, not genetic engineering — to add desired flavors while not compromising the traits needed for it to thrive commercially. "I figure that with approximately five key genes we could very significantly improve flavor," he said. He said three genes that control the production of key flavor compounds have already been located. The next step is to identify versions of the genes that lead the tomato plant to produce more of them.
The chemistry of tomato flavor has three primary components: sugars, acids and what are known as volatile chemicals — the flavor compounds that waft into the air carrying the fruit's aroma. There are more than 400 volatiles in a tomato, and Dr. Klee and his collaborators set out to first determine which ones are the most important in making a tasty tomato.
This involved grinding up a lot of tomatoes, looking at what was in them, and asking a lot of people to taste them (unpulverized), gathering comments like "a bland firm watermelon," "soft and sloppy," and "Sweet! Finally a sample with some sweetness."
From there, Dr. Klee and his collaborators, who include Linda Bartoshuk, director of human research at the university's Center for Smell and Taste, used statistics to correlate people's preferences with the presence, or absence, of particular flavor compounds, to devise a chemical recipe for the ideal tomato.
The supermarket tomato — even when grown with care and picked ripe — did not excel. "The best it will do is middle-of-the-pack," Dr. Klee said.
Cherry Roma tomatoes were at the top of the charts, followed by heirloom varieties like Matina, Ailsa Craig and Bloody Butcher. Other heirlooms like Marmande and Oaxacan Pink ranked at the bottom, below the supermarket tomatoes, though perhaps these particular types just do not grow well in Florida.
The taste analysis produced several surprises. Some compounds, abundant in many tomato varieties and thus thought to be major contributors to flavor, turned out to be irrelevant, while others, in scant quantities, had major influences. With the new knowledge, "you can't help but get a better tomato," Dr. Bartoshuk said.
This article has been revised to reflect the following correction:
Correction: August 28, 2013
An article on Tuesday about the quest for a tastier supermarket tomato misstated part of the name of one variety of heirloom tomato. It is Ailsa Craig (not Alisa).
This article has been revised to reflect the following correction:
Correction: August 30, 2013
An article on Tuesday about building a better mass-market tomato misstated the amount of money it would take to get regulatory approval to sell a genetically engineered tomato. It would cost an estimated $15 million, not $1.5 million.
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