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Tomato

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Cross-section and full view of a hothouse (greenhouse-grown) tomato.

Cross-section and full view of a hothouse (greenhouse-grown) tomato.

Cherry tomatoes

Cherry tomatoes

Roma or Bangalore Tomatoes (Indian hybrid)

Roma or Bangalore Tomatoes (Indian hybrid)

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. The fruit is rich in Lycopene, which may have beneficial health effects.

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 flavourful crops at the cost of disease resistance and productivity. In 1973, Israeli scientists developed the world’s first long shelf-life commercial tomato varieties.

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.

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.
  • 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 that keep for months in storage.

Most modern tomato cultivars are smooth surfaced, but some older tomato cultivars and most modern beefsteaks often show pronounced ribbing, a feature that may have been common to virtually all pre-Columbian cultivars. While virtually all commercial tomato varieties are red, some cultivars – especially heirlooms – produce fruit in other colours, including green, yellow, orange, pink, black, brown, ivory, white, and purple. Such fruits are not widely available in grocery stores, nor are their seedlings available in typical nurseries, but they can be bought as seed.

There is also a considerable gap between commercial and home-gardener cultivars; home cultivars are often bred for flavour to the exclusion of all other qualities, while commercial cultivars are bred for such factors as consistent size and shape, disease and pest resistance, suitability for mechanized picking and shipping, and ability to be picked before fully ripening.

Heirloom Tomatoes

Heirloom Tomatoes

Picking and ripening

Tomatoes are often picked unripe (and thus coloured green) and ripened in storage with ethylene. Unripe tomatoes are firm. As they ripen they soften until reaching the ripe state where they are red or orange in colour and slightly soft to the touch. Ethylene is a hydrocarbon gas produced by many fruits that acts as the molecular cue to begin the ripening process. Tomatoes ripened in this way tend to keep longer, but have poorer flavour and a mealier, starchier texture than tomatoes ripened on the plant. They may be recognised by their colour, which is more pink or orange than the other ripe tomatoes’ deep red, depending on variety.

Recently, stores have begun selling “tomatoes on the vine”, which are determinate varieties that are ripened or harvested with the fruits still connected to a piece of vine. These tend to have more flavour than artificially ripened tomatoes (at a price premium).

Slow-ripening cultivars of tomato have been developed by crossing a non-ripening cultivar with ordinary cultivars. Cultivars were selected whose fruits have a long shelf life and at least reasonable flavour.

At home, fully ripe tomatoes can be stored in the refrigerator, but are best kept at room temperature. Tomatoes stored cold will still be edible, but tend to lose flavour.

Consumption

Tomates farcies végétariennes

Tomates farcies végétariennes

Suquet de peix (Catalan cuisine)

Suquet de peix (Catalan cuisine)

The tomato is now grown and eaten around the world. It is used in diverse ways, including raw in salads, and processed in to ketchup or tomato soup. Unripe green tomatoes can also be crumbed 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 preserving 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 savoury flavour.

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. A study done by researchers at Manchester and Newcastle universities revealed that tomato can protect against sunburn and help keeping the skin looking youthful. 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.

Tomato consumption might be beneficial for reducing cardiovascular risk associated with type 2 diabetes.

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 flavour.

Tomato – a Fruit or a Vegetable?

Botanically, a tomato is a fruit: the ovary, together with its seeds, of a flowering plant. However, the tomato has a much lower sugar content than other edible fruits, and is therefore not as sweet. Typically served as part of a salad or main course of a meal, rather than at dessert, it is considered a vegetable for most culinary uses. One exception is that tomatoes are treated as a fruit in home preserving practices: they are acidic enough to be processed in a water bath rather than a pressure cooker as vegetables would require. Tomatoes are not the only food source with this ambiguity: avocados, eggplants, cucumbers, and squash of all kinds (such as zucchini and pumpkins) are all botanically fruits, yet cooked as vegetables.

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John Doe
Professor of Botanics
Born and raised in Dublin, Ireland, John is a superior specialist in growing palms and exotic plants.
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