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What's The Secret To Great Tomato Flavor?


This is SCIENCE FRIDAY. I'm John Dankosky. What if I told you I was going to cook up a pasta sauce using bananas, honey, roses, apples, melon rinds, vanilla, berries, sweaty cheese, peaches, chocolate, lawn clippings, lemongrass and a little dash of wasabi for good measure? Sounds pretty disgusting, right? Well, believe it or not, all those flavors I've just mentioned are components of a taste you probably already love: tomatoes. The taste of a tomato is really that complicated.

My next guest is on a mission to bring us better supermarket tomatoes that actually taste like tomatoes, and to do it, he's studying and cataloging the chemical constituents of great-tasting heirloom tomatoes. He published this work, this week, in the journal Current Biology. Let me introduce Harry Klee. He's a professor in the Department of Horticultural Sciences at the University of Florida in Gainesville. He joins us by phone today. Welcome to SCIENCE FRIDAY, Dr. Klee.

DR. HARRY KLEE: Thank you.

DANKOSKY: So why are supermarket tomatoes just so bad today?

KLEE: Well, there are a couple of problems. First of all, as you alluded to, the flavor is so complicated and so many ingredients all have to come together that, basically, breeding has been extremely difficult, if not impossible. But equally important, I think, is the fact that growers are simply not paid to produce good - great-tasting tomatoes. They're paid for how many pounds of red objects they put in a box, and there's a disconnect, I think, between the consumer and the grower, and there's no financial incentive for them.

DANKOSKY: If you want to talk tomatoes with us, 1-800-989-TALK. That's 1-800-989-8255. You can tweet us, @scifri. When did this start? When did they stop making tomatoes that actually tasted good?


KLEE: Well, I think, you know, you can trace it back to probably about the time of World War II when the breeders really focused on intensive breeding of tomatoes, and the focus was really on yield and shelf life and appearance. And again, because flavor is such a complicated trait, it's not like you can just go out and there's a single gene that makes a tomato taste good. So really, I think the focus on productivity has been the real key, and that's been the last 60 to 70 years.

DANKOSKY: Do you love tomatoes yourself? I mean, you're in Florida. They grow all the tomatoes there. You must love them.

KLEE: Oh, you've got that wrong.


KLEE: Actually, I really do like tomatoes, but we've tasted so many tomatoes over the last few years that I'm pretty sick of biting into a fresh tomato. I really like tomatoes in things, and I really like tomato sauce and paste, and all the things you can do with the tomato. But a plain tomato, I'm pretty tired of.

DANKOSKY: Actually, I have to tell you we brought in a variety of these supermarket tomatoes here - these things that all look beautiful to a certain extent, but they're hard, and they seemed as though they could travel just miles, and miles and miles. This is something - Butter Valley Harvest, all these tomatoes that seems, though, they're better made to travel than they really are to taste.

KLEE: Yeah. And I think that that's the case, and I think this relates to the changes in agriculture over the last 50 years, or so, where people demand a tomato year-round. And the reality is it's extremely difficult to produce a tomato in, say, for example, New York in January. Consumers really want them year-round. And so Florida produces them, and they have to be shipped great distances and last a while. And what you're seeing is the consequence of that.

DANKOSKY: So tell us about your recipe for a great-tasting tomato. How are you working on this?

KLEE: Well - so we started out going way back, preceding that period of intensive breeding, to what are commonly referred to as heirloom tomatoes. And they have an incredible diversity of flavors. Contrary to popular belief, not all heirlooms taste good, but a lot of them really do. And so what we did was we took as wide a range of heirlooms as we could get our hands on, gave them to a fairly large consumer panel and basically said, number one: how much do you like it? And number two: what's in it? And then using statistical approaches, you basically go back and say, OK, what was in the ones that tasted good versus the ones that tasted bad?

DANKOSKY: When you look at these different flavor components, are there certain key ingredients, certain key components that always make for a better-tasting tomato?

KLEE: Yeah. There are few. I mean, unfortunately, by far, the biggest one is sweetness. You know, people just like sweet. And so sugar is an important component, probably the major component. But beyond that, there are a smaller number of volatile chemicals, the things that we smell that give foods their real incredible diversity of flavors. And the nice thing is that we can zero in, now, on the most important of those compounds.

DANKOSKY: Well, why are tomatoes so complex? I can imagine that certain foods are just going to have one or two very key components, but as we started with, the tomatoes have all these different things about them. Why so complicated?

KLEE: I don't think I can answer question.


KLEE: It's very clear that if you look at something like a banana, there's one compound that really is the predominant odor that gives it that banana flavor. That's just not the case with tomatoes. They're much more complicated. You almost have, essentially orchestra that has to come together and all play together in order to make that tomato flavor. Why that's happened evolutionarily? I don't think anybody could answer that question, but it's the reality, and that's what makes the flavor of tomatoes so complicated.

DANKOSKY: If you have questions about tomatoes for our tomato expert, Harry Klee, who's trying to get a better-tasting supermarket tomato for us, you can call us at 1-800-989-8255, 1-800-989-TALK. Doug is in Brookfield, Massachusetts. Hey there, Doug. Go ahead.

DOUG: Yes. Hey, I'm enjoying your show because I'm a big fan of tomatoes.


DOUG: I grow my own. I either grow them from seeds out of a seed packet, or I get transplants from the local nursery store. So what I'm wondering is, have my tomatoes been bred to be less flavorful, or is this something that's unique to supermarkets because of all of the problems with handling them up and shipping them great distances?

KLEE: You could certainly buy seeds that are really excellent tomatoes, and there's no question that you can get a really great tomato if you're willing to grow it yourself. So, really, I think the problem that we face today is the supermarket tomato. It's the one that's been bred for a long, long shelf life and being able to travel. So you're still fine, if you can grow your own, for the two or three months that you can produce them.

DANKOSKY: You talk about a long shelf life and, of course, the tomatoes that we get in the supermarket, they have to travel well. We have to be able to grow them in abundance. Hopefully, they'll taste good, but they'll also have to look good. How much does the look of the tomato influence how the tomato is going to taste?

KLEE: That's an excellent question. The reality is it does influence it. We integrate all of our senses in terms of what we like in a tomato. So, you know, when we look at a tomato that's less than fully ripe, you look at that, you perceive that and that will actually impact how your perception of how that tomato tastes. If you think it's less ripe, you're going to taste the tomato that doesn't taste as good. So certainly, the growers have focused on that to produce something that really looks excellent. It's a small part of it, but it does play a role.

DANKOSKY: But, of course, a lot of these heirloom tomatoes, they just look ugly. They don't look good at all. But then you bite into them, and you think, now that's a tomato.

KLEE: Yeah. That - you know, and I think a large of that is, you know, companies are now starting to play upon that tomato that doesn't look perfectly round. Now, there's an expectation that it'll actually taste good. You know, the reality is that the round tomatoes that are produced commercially just don't have very flavor even though they look great.

DANKOSKY: The sugars that you talked about, it seems that that's the most complicated piece. How do you get the sweetness component, the part that everyone seems to crave out of the tomato in there. It's what is lacking in almost all of these bullet-shaped, very hard tomatoes that I get in the supermarket.

KLEE: Yeah, and I think, basically, the breeders have focused mostly on sugar because it's easy to assay, and I think it's basically been maxed out. You know, basically, if you think about the way that a plant grows, what the growers, or the breeders rather, have done is they've really maximized the potential of the plant to produce fruit. And commercial tomatoes produce very large amounts of fruit at the same time, and the plant can't keep up with that. It can only fix so much light and turn it into sugar. And you basically - what you do is you dilute out the flavor. The heirlooms, in contrast, you know, you'll get a great-tasting fruit, but you might get two or three fruit at a time, if that. And, you know, I think part of the secret as to why the tomatoes have degraded over time is the emphasis on really high yields that have really maxed out the ability of the plant to produce nutrients.

DANKOSKY: Now that you've identified a lot of these chemical components, what's the next step for you in building this perfect tomato? How long is it going to take?

KLEE: Well, we have some really nice stuff right now that's probably not at the level where a commercial grower could grow it, but we've made some high breeds between modern varieties have this good disease resistance and some of these really old heirlooms, and you get a high breed that actually produces pretty good fruit. And I think we could potentially put some of those out for people in the not-too distant future, I mean, within the next year or so.

I think it's going to be much more difficult to engineer in that flavor using traditional breeding methods into the commercial tomato because the commercial grower is not going to touch it. Again, this comes back to they're not paid to produce a really good flavor. So we have to put it in there in the context of this high-yielding, great ship-ability varieties that are disease-resistant and that's going to take several years. But the goal, once we know now which chemicals to focus on, is to identify the genes that will improve the concentrations of those compounds and, through traditional breeding, get them back into those commercial varieties. So I would say less than a year for something that potentially a home gardener could grow or a small person who's not so focused on high yields, but several years more for the commercial Florida tomato.

DANKOSKY: Now, I have to say, when you say, engineering, that's going to scare a lot of people. Are you using genetic engineering to make these better tomatoes or traditional breeding?


DANKOSKY: How's it working?

KLEE: Unfortunately, you know, if we could use genetic engineering, we could probably do this in less than half the time, but it's, you know, the atmosphere today with GMOs is kind of poisonous. And the reality is that a university, a public institution probably could never afford to go through all of the work that - and the paperwork and the testing that's required for a GMO. So that's not our intention. It's going to add several years, but we would - definitely, we won't do that.

DANKOSKY: I'm John Dankosky and this is SCIENCE FRIDAY from NPR. Let's go to our phones. Joe(ph) is in Charleston, South Carolina. Hi there, Joe. Oh, let's move on. You know, let's go to Tom(ph) in Gainesville, Florida. Hi, Tom. Go ahead.

TOM: Yeah, hey. Interested in how hydroponics will affect the tomato's sweetness or cost or just any comparison to the conventional growing.

DANKOSKY: Thanks, Tom.

KLEE: Good question. I - you know, in general, how you grow the tomatoes, you know, the wine growers, wine grape growers had figured this out centuries ago. How you grow it and where you grow it is really important, and I personally think that hydroponic tomatoes are probably not going to be as flavorful as something that's grown in a rich soil. And, you know, that's what a lot of the greenhouse growers now are doing. They're growing them with an artificial media with, basically, just water and nutrients, and I don't think you'll get as good a tomato that way.

DANKOSKY: But why not?

KLEE: You know, the reality is that, again, much like wine grapes, stress is good. Stress puts pressure on the plant. It makes - it grows differently. It just, I think, produces a tomato that tastes better.

DANKOSKY: Isn't that really then part of the problem with the way we're approaching getting tomatoes to Americans year round is we're not really creating much stress on the plants. We're just trying to grow as many tomatoes as possible. Is that part of the solution, just put these plants under a little bit more of the type of conditions that grow great tomatoes in Italy and places like that?

KLEE: If you took the modern, commercial tomato and grew it in your backyard and let the fruit fully ripen, it wouldn't be a great tomato, but it would be a good tomato and so, yes. I mean, I think that, again, it keeps coming back to the focus on high yields and just pumping out as many tomatoes as you can is really a detriment to flavor and - but, you know, that's the economic reality. Until we have a system where the grower - you know, if you could make the grower get paid more for producing a great tomato, the grower would do that, and you'd get a great tomato, but it's just not the current situation.

DANKOSKY: Rodney(ph) is on the line from Pensacola, Florida. Hi there, Rodney.

RODNEY: Hi. How are you today?

DANKOSKY: Doing good.

RODNEY: I've got a brown tomato that I'm growing up. I got about 20 plants in the garden right now. It's - I picked up the seeds from a tomato that I saved out of the supermarket, and it's brown in color where it ripens, approaching black perhaps. And now I haven't had one since last year. But if I remember the reason for saving it, it was because it has great taste and I imagine it's a trade tomato like called the kumato or something like that. But that's the first brown or black one I've ever seen.

DANKOSKY: Yeah, I've actually - I've got a kumato sitting here in front of me. It's not kind of black. It's the sort of greenish weird color, but...

RODNEY: Really?


DANKOSKY: Yeah. It's what one of this supermarket kumatos that you can get here in New York. Harry Klee?

KLEE: Yes.

DANKOSKY: Now, I'm wondering if - can you comment on his brown tomato? I mean, red isn't the only good color here.

KLEE: Yeah. There are lots of colors. And so what - the reason that they're brown is because the chlorophyll that normally is in a green tomato doesn't break down. And then the carotenoids, which give it color, start to accumulate, and you basically are getting red and green together to give you brown. I have never tasted one of them. People say that they taste quite good. We don't have them in our supermarkets in Gainesville, but I've heard that they're - they taste good. They're certainly interesting and different from what's out there in the standard red tomato.

DANKOSKY: Well, we've just about run out of time. I want to thank you, Harry Klee, and thank you for trying to grow a better tomato. We're going to be anxiously awaiting this in our supermarkets here.

KLEE: So am I.


KLEE: Thank you for having me.

DANKOSKY: Thanks for all your work. Harry Klee is a professor in the Department of Horticultural Sciences at the University of Florida in Gainesville. Transcript provided by NPR, Copyright NPR.