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Tomatoes: Bursting with Nutrition

by Berkeley Wellness

Although botanically a fruit—specifically, a berry—the tomato is prepared and served as a vegetable. In this country, the Supreme Court officially proclaimed the tomato a vegetable in 1893 as a result of a tariff dispute.

Tomatoes are members of the nightshade family, which includes deadly nightshade as well as potatoes, bell peppers, and eggplant.

The tomato is a native South American plant that was brought to Europe by Spanish explorers in the 1500s. Europeans, however, believed it to be poisonous and used it only as an ornamental houseplant. Not until the 1800s was the tomato widely accepted as a food, and even then it was customarily cooked for hours to neutralize its “poisons.” Only in the second half of that century were raw or lightly cooked tomatoes eaten by Europeans and Americans.

Types of Tomatoes

There are thousands of tomato varieties. Here's a guide to the main categories, plus a primer on canned tomatoes.

Tomatoes: nutrition

Extremely popular and highly versatile, tomatoes provide dietary fiber, some B vitamins, iron, potassium, and a good amount of vitamin C. Cherry tomatoes and fresh plum tomatoes are a decent low-fat source of the antioxidant vitamin E. Iron and potassium are found in ample amounts in canned tomatoes and also in sun-dried tomatoes, which are another good source of fiber. Tomatoes are the major dietary source of the carotenoid lycopene.

For a full listing of nutrients, see the National Nutrient Database:

The picking stage

To increase their durability, tomatoes are picked when they are still green—a stage referred to as “mature green”—or just when they begin to show a spot of pink at the blossom end, a stage known as “breaker.” Tomatoes at either stage are fully developed, they just haven’t begun the ripening process.

To speed along the ripening process of mature green and breaker-stage tomatoes, growers and shippers often place them in an atmosphere containing ethylene gas. Though it sounds like a synthetic creation, ethylene is the same organic compound (actually a ripening hormone) produced naturally by many fruits—oranges, bananas, honeydew melons—as well as by tomatoes. Left on the vine, a tomato will produce its own ethylene, but the external application of ethylene gas is used to initiate and promote the ripening process.

Since not all tomatoes in a crop develop at the same rate, it is inevitable that some will be picked too early, and you may occasionally get a tomato that, although it turns completely red, never develops a palatable flavor or texture. But if handled properly most of these tomatoes have the potential to develop good flavor and juicy texture. A study at the University of Georgia compared tomatoes left on the vine to ripen to those treated with ethylene and found that the treated tomatoes have the same “sensory attributes and post-harvest quality” and only minor differences in taste and texture.

How to Choose the Best Tomatoes

Ripe tomatoes are fragrant; if they have no aroma at all, they were probably picked when immature, and will never ripen.

Are “vine ripened” better?

Unfortunately, the term “vine ripened” has no standard definition and is usually misleading (if not an outright marketing lie). Usually it refers to tomatoes that have been picked at the breaker stage—mature but unripened—but tomatoes picked at any time can carry the label. Generally, tomatoes shipped to nearby markets are picked at a greater degree of ripeness than tomatoes shipped across the country. Most greenhouse (“hothouse”) tomatoes are grown close to their market, so they stand a greater chance of being left on the vine a bit longer.

The importance of temperature

To help ensure that the tomatoes you buy will at least taste adequate, don’t buy any that have been refrigerated. Exposure to temperatures under 55° during growth or after harvest prevents a tomato from ripening satisfactorily.

Shippers and retailers sometimes keep tomatoes with other vegetables, like lettuce or broccoli, under refrigeration, destroying their ripening potential. And it’s difficult to identify a previously refrigerated tomato until you get it home and slice it. If it’s been refrigerated, the skin pulls away easily from the flesh, and the tomato will be mealy and virtually tasteless.

About all you can do is ask the produce manager of the supermarket, who might be able to tell you how the tomatoes were stored and shipped prior to their arrival at the store. The produce manager should be able to tell you what the storage conditions at the store have been. Almost all supermarket tomatoes (except those previously refrigerated) will benefit from ripening at home at room temperature for a few days in a paper bag alongside an apple or a banana.

How to store tomatoes at home

Room temperature (above 55°) is best for storing tomatoes. Don’t refrigerate them. Place less-than-ripe tomatoes in a paper bag with an apple or banana. The ethylene gas given off by the fruit will hasten the ripening process. Keep the tomatoes out of sunlight—they will overheat and ripen unevenly—and arrange them, stem-side up, to prevent bruising. Once the tomatoes are red and yield to the touch, they will keep for a day or two at room temperature.

12 Ways to Serve Tomatoes

Tomatoes add tantalizing flavor to many dishes, from salads and sauces to broiled vegetables and stir-fries. Here are a few tips about to prepare tomatoes, followed by a dozen tasty serving suggestions.

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