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A Question of Taste
Why do the tomatoes that you buy in the supermarket
taste so bland?

by Jim Caddick
corn

I was a country boy. I grew up on an Ohio farm, and one of the few things I miss about Ohio is being able to go out into the garden during the summer, pick a ripe sun-warmed tomato off the vine, brush it off, and eat it right on the spot. The flavor is indescribable. But if you are like most people, you have very little idea of what I mean.

This is not because you are unacquainted with tomatoes. Although the tomato ranks sixteenth in relative nutritional content for a group of vitamins and minerals (well behind such stalwarts as broccoli, spinach, and brussels sprouts, which are the top three), we Americans eat so many of them that it is the number one source of nutrients in our diet. Statistically speaking, each of us consumes about sixty-five pounds of tomatoes and tomato products per year.

This consumption has increased since the end of World War II. In the 1930's, American farmers grew approximately one million pounds of tomatoes annually. By 1987, that figure had ballooned to 76,020 million pounds. Due partly to the increase in fast food outlets, nearly one half of our total tomato consumption is in the form of ketchup and chili sauce. Fresh tomato consumption has actually decreased slightly. But when I look at the tomatoes in the supermarket, I wonder why we bother eating them at all. The taste of these fresh tomatoes bears little resemblance to my childhood memories.

To understand why, let's first look at what makes a ripe tomato.

It takes about forty to sixty days from the time the tomato flower is fertilized until the fruit reaches full maturity. It attains its full size in about half that time, having accumulated starch all the while. Since the fruit is still grass green, growers call this the "mature green" stage. As the days go by, the green chlorophyll in the fruit is degraded and eventually destroyed as the final yellow or red pigmentation increases. The fruit, now called a "breaker," has a mottled or streaked appearance. As the tomato ripens to its full color, its acidity decreases, essential oils and other components of its flavor develop, the starch becomes sugar, and the fruit softens.

The amount of sunlight the tomato plant receives during the growth and ripening of the fruit is a critical factor in how a tomato both looks and tastes. This is why tomatoes grown in San Francisco, which is often overcast during the summer, usually taste bland, if they ripen at all. Special varieties bred for shade tolerance have been produced, but have had only moderate success.

Once a fully ripened tomato is picked, its flavor deteriorates quickly. There are more than four hundred compounds, aromatic as well as flavorful, in the fruit. They all act in concert to let you know you are eating a tomato rather than a turnip. After the fruit is picked, these compounds rapidly deteriorate. Just two hours off the vine, a tomato has lost some of the factors that make it taste so good. The flavor also suffers if a ripe tomato is kept for more than a few hours in a refrigerator.

"Aha! So that's why they taste so bad nowadays!" you say. "Tomatoes are picked long before I see them in the supermarket, and have probably been refrigerated as well." Unfortunately, it's not that simple.

The present-day tomato has been molded by the "green revolution," which began in the 1950's. Selective breeding, improved cultivation methods (including the use of pesticides), and mechanization let less than ten percent of the population of the United States feed everyone else, with enough food left over to export abroad.

While the number of farmers has decreased, the size of the farm has increased. In 1890, the average farm size was 136 acres. By 1930, it had grown slightly to 156 acres. Today the figure is closer to 500 acres. Farming has, for the most part, ceased to be a vocation, and has become an industry, with a number of large agri-business corporations participating. Giants such as Dow, Sohio, Ciba-Geigy and Monsanto not only supply pesticides, seeds, machinery and the other raw materials farmers need, but are also major sources of research funding. This research includes development of new tomato varieties that are both more resistant to herbicides (which these companies also happen to sell) and better suited to mechanized harvesting.

The typical tomato plant tends to sprawl over a fairly wide area and is relatively easy to break or damage. Also, the fruit does not all ripen at once: the same plant can have ripe tomatoes, green tomatoes and new flowers, all at the same time. Harvesting machinery would damage the delicate vines. And obviously, only the ripe fruit should be picked. Building a machine to fit the tomato was not a practical solution. Growers found it much easier to engineer the tomato to fit the requirements of the machine.

The varieties of tomatoes bred specifically for mechanical picking have a more compact plant and fruit which ripens more or less all at the same time. The mechanical picker uproots the plant and destroys it as it gathers in the fruit, so the tomato also has a tougher skin to withstand this rough treatment.

While growers were improving certain tomato characteristics, the flavor tended to get lost in the shuffle. But these re-engineered varieties are overwhelmingly used for processing. Only about one percent of the tomatoes destined for the fresh market are picked mechanically.

You may have heard rumors of tomatoes that can withstand a drop of six feet without damage or those that will not ripen even on the vine unless they are specifically treated. Although generally true, these tales have nothing to do with the fresh tomatoes on your grocer's shelves.

Shipping requirements, not harvesting needs, have had a greater impact on the taste of the fresh tomato. Prior to World War II, major metropolitan areas were ringed with numerous local producers who brought small quantities of fresh fruits and vegetables a short distance into town for sale. Economic pressures among them the increased demand for housing have pushed farmers further away from the cities.

The problem farmers face is getting their product (the tomato) to the consumer (you). When a farmer deals with small quantities transported over small distances, it's no big problem. But shipping a ton of ripe tomatoes is another thing. They squish. They spoil. They're likely to arrive better suited for throwing than eating. But the vast majority of tomatoes sold in the United States are grown in either California or Florida and shipped to the rest of the country. Tomatoes from California arrive in East Coast markets in five to six days; tomatoes from Florida arrive in three.

So how do shippers manage it? The answer and one of the prime reasons for the loss of flaovr for the tomato was discovered in the 1930's. Ethylene gas, a normal by-product of fruit development, was shown to be a trigger that prompted the ripening process. Many fruits, tomatoes included, could be picked while still green (and much more resistant to damage during transport), brought to market, and ripened using ethylene while in storage.

Mature green tomatoes can be kept in storage at around 10 degrees Celsius (50 degrees Fahrenheit) for about three weeks. Or they can be stored in special holding rooms which have a low-oxygen atmosphere for up to ten weeks without spoilage or further ripening. At any time within this period, the tomatoes can be treated with ethylene gas and be ready to hit your grocer's shelves in about two to three weeks. A fully ripe tomato could be stored under similar conditions for only about one week.

But there's a catch: (Isn't there always?) Ethylene acts as a catalyst in initiating the sequence of events in the ripening process, but many of the flavor components I mentioned earlier need the plant's continuing contributions to fully develop. Removed from the plant while still green, immature fruit treated with ethylene colors up very nicely and looks beautiful, but falls short of its optimum quality.

Focusing on the use of ethylene obscured another reason for tasteless tomatoes. This is your desire to have ripe, luscious tomatoes year-round not only in July, but also in January. Like most fruits and vegetables, the tomato is seasonal. California tomatoes are in season from mid-April to December, but the demand for tomatoes is year-round. It is a safe bet that the tomato you sliced for your salad in February came all the way from Mexico or out of storage. If you were not so eager to buy tomatoes, the techniques to deliver them to you would not have been developed.

You may have bought some tomatoes in wintertime that were horribly expensive, looked wonderful, but were watery when cut and had little taste. These tomatoes came from greenhouses where they were hydroponically grown in special non-nutritive material, getting all their nutrients in liquid form. Because of the costs involved, this method of production is not used to any extent here in the United States, but is more prevalent in Europe, where weather conditions make for an otherwise short growing season. To some extent, this wateriness is also true of tomatoes which are heavily irrigated, since the water is stored in the flesh in anticipation of a dry spell that never comes.

Is there hope for tasty tomatoes in the future? Well, genetic engineering techniques have brought tomatoes with softer skins which the makers claim retain their flavor. And to be fair, modern techniques have their advantages. Compared to the general store of fifty years ago, the modern supermarket offers an enormous variety of produce. And, relative to earning power, we don't have to pay as much for these fruits and vegetables. But it may well be that, unless I start growing my own tomatoes, and eating them immediately after I pick them, my memories of the taste of a tomato will remain only memories.

 


copyright Exploratorium 2001