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Monday, May 16, 2011

Fruit of the desert is now flavour of the month

The New York Times on Wednesday, 11 May, ran a feature article on pitayas, or 'dragon fruits' as they are commonly called. These are native to Bolivia, with a natural range from Bolivia to Mexico. It has taken root in the southwestern US, southeast Asia and Israel.
'It' is a bit of a vague term though, and the article does not go into such detail, so let me expound a bit further and note that in general, pitaya or dragon fruit refers to vine-like epiphytic Hylocereus cacti; these bloom only at night, giving rise to a large white fragrant flower known as 'moonflower' or 'Queen of the Night'. They are also grown ornamentally.
There are sweet and sour pitayas, the latter usually belonging to the genus Stenocereus, which grows in the arid regions of the Americas. Sweet pitayas have a creamy pulp and a delicate aroma. Fruits of some other columnar cacti (mainly Cereeae) are also called "pitayas" – for example those of the Peruvian Apple Cactus (Cereus repandus), which are very rare. Sweet pitayas come in three types, all with leathery, slightly leafy skin, and include:
Hylocereus undatus (red pitaya) has red-skinned fruit with white flesh. This is the most commonly-seen 'dragon fruit'.
H. costaricensis (Costa Rica pitaya, often called H. polyrhizus) has red-skinned fruit with red flesh.
H. megalanthus (yellow pitaya, formerly in Selenicereus) has yellow-skinned fruit with white flesh.
After thorough cleaning of the seeds from the pulp of the fruit, the seeds may be stored when dried. Ideally, the fruit must be unblemished and overripe. Seeds grow well in a compost or potting soil mix - even as a potted indoor plant. Pitaya cacti usually germinate between 11 and 14 days after shallow planting. As they are cacti, overwatering is a concern for home growers. As their growth continues, these climbing plants will find something to climb on, which can involve putting aerial roots down from the branches in addition to the basal roots. Once the plant reaches a mature 10 lbs weight, one may see the plant flower.Polinisation is by nocturnal creatures such as bats or moths; they do not self-fertilise. The plants handles up to 40 °C (104oF) and very short periods of frost, but does not survive long exposure to freezing temperatures. The cacti thrive most in USDA zones 10-11, but may survive outdoors in zone 9a or 9b. Hylocereus has adapted to live in dry tropical climates with a moderate amount of rain. The dragon fruit sets on the cactus-like trees 30–50 days after flowering and can sometimes have 5-6 cycles of harvests per year. There are some farms in Vietnam that produce 30 tons of fruit per hectare every year.
The typical nutritional values per 100 g of raw pitaya (of which 55 g are edible) are as follows:
Water 80-90 g
Carbohydrates 9-14 g
Protein 0.15-0.5 g Fat 0.1-0.6 g
Fiber 0.3-0.9 g
Ash 0.4-0.7 g
Calories: 35-50
Calcium 6–10 mg
Iron 0.3-0.7 mg
Phosphorus 16 – 36 mg
Carotene (Vitamin A) traces
Thiamine (Vitamin B1) traces Riboflavin (Vitamin B2) traces
Niacin (Vitamin B3) 0.2-0.45 mg
Ascorbic acid (Vitamin C) 4–25 mg