Tomato may refer to both the plant (Solanum lycopersicum) and the edible, typically red, fruit which it bears. Originating in South America, the tomato was spread around the world following the Spanish colonization of the Americas, and its many varieties are now widely grown, often in greenhouses in cooler climates.
The tomato fruit is consumed in diverse ways, including raw, as an ingredient in many dishes and sauces, and in drinks. While it is botanically a fruit, it is considered a vegetable for culinary purposes (as well as by the United States Supreme Court, see Nix v. Hedden), which has caused some confusion. The fruit is rich in lycopene, which may have beneficial health effects.
The tomato belongs to the nightshade family. The plants typically grow to 1–3 metres (3–10 ft) in height and have a weak stem that often sprawls over the ground and vines over other plants. It is a perennial in its native habitat, although often grown outdoors in temperate climates as an annual.
Varieties
There are around 7500 tomato varieties grown for various purposes. Heirloom tomatoes are becoming increasingly popular, particularly among home gardeners and organic producers, since they tend to produce more interesting and flavorful crops at the cost of disease resistance and productivity.
Tomato varieties are roughly divided into several categories, based mostly on shape and size.
“Slicing” or “globe” tomatoes are the usual tomatoes of commerce, used for a wide variety of processing and fresh eating.
Beefsteak tomatoes are large tomatoes often used for sandwiches and similar applications. Their kidney-bean shape, thinner skin, and shorter shelf life makes commercial use impractical.
Oxheart tomatoes can range in size up to beefsteaks, and are shaped like large strawberries.
Plum tomatoes, or paste tomatoes (including pear tomatoes), are bred with a higher solids content for use in tomato sauce and paste, and are usually oblong.
Pear tomatoes are obviously pear-shaped, and are based upon the San Marzano types for a richer gourmet paste.
Cherry tomatoes are small and round, often sweet tomatoes generally eaten whole in salads. Grape tomatoes, a more recent introduction, are smaller and oblong, a variation on plum tomatoes, and used in salads. Campari tomatoes are also sweet and noted for their juiciness, low acidity, and lack of mealiness. They are bigger than cherry tomatoes, but are smaller than plum tomatoes.
Early tomatoes and cool-summer tomatoes bear fruit even where nights are cool, which usually discourages fruit set. There are also varieties high in beta carotenes and vitamin A, hollow tomatoes and tomatoes which keep for months in storage.
Tomatoes are also commonly classified as determinate or indeterminate. Determinate, or bush, types bear a full crop all at once and top off at a specific height; they are often good choices for container growing. Determinate types are preferred by commercial growers who wish to harvest a whole field at one time, or home growers interested in canning. Indeterminate varieties develop into vines that never top off and continue producing until killed by frost. They are preferred by home growers and local-market farmers who want ripe fruit throughout the season. As an intermediate form, there are plants sometimes known as vigorous determinate or semideterminate; these top off like determinates, but produce a second crop after the initial crop. The majority of heirloom tomatoes are indeterminate, although some determinate heirlooms exist. Hybrid plants remain common, since they tend to be heavier producers, and sometimes combine unusual characteristics of heirloom tomatoes with the ruggedness of conventional commercial tomatoes.
Consumption
The tomato is now grown and eaten around the world. It is used in diverse ways, including raw in salads, and processed into ketchup or tomato soup. Unripe green tomatoes can also be breaded and fried, used to make salsa, or pickled. Tomato juice is sold as a drink, and is used in cocktails such as the Bloody Mary.
Tomatoes are acidic, making them especially easy to preserve in home canning whole, in pieces, as tomato sauce or paste. The fruit is also preserved by drying, often in the sun, and sold either in bags or in jars with oil.
Tomatoes are used extensively in Mediterranean cuisine, especially Italian and Middle Eastern cuisines. They are a key ingredient in pizza, and are commonly used in pasta sauces. They are also used in gazpacho (Spanish cuisine) and pa amb tomàquet (Catalan cuisine).
Though it is botanically a berry, a subset of fruit, the tomato is a vegetable for culinary purposes, because of its savory flavor.
Nutrition
Tomatoes are now eaten freely throughout the world, and their consumption is believed to benefit the heart, among other organs. They contain the carotene lycopene, one of the most powerful natural antioxidants. In some studies, lycopene, especially in cooked tomatoes, has been found to help prevent prostate cancer, but other research contradicts this claim. Lycopene has also been shown to improve the skin’s ability to protect against harmful UV rays. Natural genetic variation in tomatoes and their wild relatives has given a genetic plethora of genes that produce lycopene, carotene, anthocyanin, and other antioxidants. Tomato varieties are available with double the normal vitamin C (Doublerich), 40 times normal vitamin A (97L97), high levels of anthocyanin (resulting in blue tomatoes), and two to four times the normal amount of lycopene (numerous available cultivars with the high crimson gene).
Medicinal properties
Lycopene has also been shown to protect against oxidative damage in many epidemiological and experimental studies. In addition to its antioxidant activity, other metabolic effects of lycopene have also been demonstrated. The richest source of lycopene in the diet is tomato and tomato derived products. Tomato consumption has been associated with decreased risk of breast cancer, head and neck cancers and might be strongly protective against neurodegenerative diseases. Tomatoes and tomato sauces and puree are said to help lower urinary tract symptoms (BPH) and may have anticancer properties.
Storage
Tomatoes that are not yet ripe are optimally stored at room temperature uncovered, out of direct sunlight, until ripe. In this environment, they have a shelf life of three to four days. When ripe, they should be used in one to two days. Tomatoes should only be refrigerated when well ripened, but this will affect flavor.
Safety.
Plant toxicity
Like many other nightshades, tomato leaves and stems contain atropine and other tropane alkaloids that are toxic if ingested. Ripened fruit does not contain these compounds. Leaves, stems, and green unripe fruit of the tomato plant contain small amounts of the poisonous alkaloid tomatine. Use of tomato leaves in tea (tisane) has been responsible for at least one death. However, levels of tomatine are generally too small to be dangerous. Tomato plants can be toxic to dogs if they eat large amounts of the fruit, or chew plant material.