Dragon fruit

Dragon fruit, also called pitahaya or pitaya, is the fruit of several plants in the cactus family. The main type is Selenicereus undatus.

Dragon fruit first grew in the southern parts of Mexico and along the Pacific coast of Guatemala, Costa Rica, and El Salvador. In the 21st century, it has also been grown in places like Vietnam, China, Colombia, and Southeast Asia.

For fruit of the genus Stenocereus, see Pitaya (Stenocereus). For other uses, see Pitahaya (disambiguation).

Description

The dragon fruit is a juicy cactus that can survive long periods without rain, which is called drought resistance. It has long, three-sided stems and often wraps around nearby trees. It takes moisture from their bark. The stems can climb 8 to 10 metres (26 to 33 ft) without growing into the ground. Its flower has a tube shape and has both male and female parts. It opens only once, at night, and its smell attracts insects. The flower can self-pollinate, but other plants can also pollinate it. Bats are a natural pollinator.

The fruit grows from pollination to harvest in 4 to 8 weeks, depending on the temperature. It is oval-shaped, about 10 by 6 centimetres (3.9 by 2.4 in). Before it ripens, the inside is green. Later it turns yellow or red, depending on the type. The soft inside holds small black seeds. The skin is covered with bright red or yellow, fleshy, ovate scales. The red and purple colours of some Selenicereus fruits come from betacyanins, a group of coloured substances that includes betanin. Betanin also gives beets, Swiss chard and amaranth their red colour.

Species

Dragon fruit mainly comes in three types. Selenicereus undatus has pink skin and white flesh, and it is the most commonly seen kind. Selenicereus costaricensis has red skin and red flesh. Selenicereus megalanthus has yellow skin and white flesh, and it is often called "yellow dragon fruit."

Each fruit weighs about 150 to 600 grams, and some can be as heavy as 1 kilogram. Early fruits brought from Colombia to Australia had different names. One was Hylocereus ocampensis, also called Cereus repandus, which was the red fruit. Another was Cereus triangularis, which people thought was the yellow fruit.

Cultivation

Seeds are cleaned from the pulp and dried. The best fruit is ripe and has no marks. The seeds grow in compost or potting soil, including in pots indoors. The young cacti sprout 11 to 14 days after they are planted near the surface. As they grow, they look for something to climb on. Once a plant reaches 4.5 kilograms (10 pounds), it may flower. Farms plant 1,100 to 1,350 plants per hectare (445 to 546 per acre). A plant can take up to 60 months (260 weeks) to produce a full crop. Farms can expect yields of 20 to 30 metric tons (22 to 33 short tons).

Dragon fruit flowers open at night and usually wilt by evening. They depend on pollinators that are active at night, such as bats or moths. Some kinds cannot make fruit by pollinating themselves. Pollinating with a different plant of the same kind usually leads to better fruit set and quality. The plants can flower three to six times a year. They can survive heat up to 40 °C (104 °F) and short frosts, but not long freezing. They grow best in USDA zones 10–11 and may survive outdoors in zone 9a or 9b. The plants are suited to dry tropical areas. In many places they have escaped cultivation and grown wild as a weed. In some countries, they are classed as an invasive weed. Large amounts are grown in Vietnam, China, Mexico, Colombia, Southeast Asia, and Australia. Vietnam grows Selenicereus undatus.

Stems and fruits can be harmed by diseases caused by fungi, bacteria, nematodes, and viruses. Too much water can make flowers drop and fruit rot. One bacterium, Xanthomonas campestris, causes stems to rot. Dothiorella fungi can cause brown spots on fruit. Other fungi that infect fruit include Botryosphaeria dothidea, Colletotrichum gloeosporioides, and Bipolaris cactivora.

Nutrition

Raw dragon fruit is mostly water, about 84%. About 15% of it is carbohydrates. It has very little protein and fat. A 100-gram (3.5 oz) serving gives 57 kilocalories (240 kilojoules) of food energy. It does not have large amounts of any micronutrients.

Culinary

When cut in half, a raw dragon fruit can be eaten with a spoon. Its juice can add flavor and color to drinks, baked goods, or candy. The flowers can be eaten as a vegetable or made into a tea.

Seed oils

The seed oils of Selenicereus costaricensis, also known as Hylocereus costaricensis (red-fleshed pitaya), and Selenicereus undatus, also known as Hylocereus undatus (white-fleshed pitaya), have similar fats. These include palmitic acid, stearic acid, palmitoleic acid, and mostly oleic acid (22%) and linoleic acid (50%).