The fruit has a distinct warty looking exterior and an oblong shape. It is hollow in cross-section, with a relatively thin layer of flesh surrounding a central seed cavity filled with large flat seeds and pith. Seeds and pith appear white in unripe fruits, ripening to red; they are not intensely bitter and can be removed before cooking. However, the pith will become sweet when the fruit is fully ripe, and the pith's color will turn red. The pith can be eaten uncooked in this state, but the flesh of the melon will be far too tough to be eaten anymore. Red and sweet bitter melon pith is a popular ingredient in some special southeast Asian style salad. The flesh is crunchy and watery in texture, similar to cucumber, chayote or green bell pepper. The skin is tender and edible. The fruit is most often eaten green. Although it can also be eaten when it has started to ripen and turn yellowish, it becomes more bitter as it ripens. The fully ripe fruit turns orange and mushy, is too bitter to eat, and splits into segments which curl back dramatically to expose seeds covered in bright red pulp. Bitter melon comes in a variety of shapes and sizes. The typical Chinese phenotype is 20 to 30 cm long, oblong with bluntly tapering ends and pale green in color, with a gently undulating, warty surface. The bitter melon more typical of India has a narrower shape with pointed ends, and a surface covered with jagged, triangular "teeth" and ridges. Coloration is green or white. Between these two extremes are any number of intermediate forms. Some bear miniature fruit of only 6 - 10 cm in length, which may be served individually as stuffed vegetables. These miniature fruit are popular in Southeast Asia as well as India.
Bitter melons are seldom mixed with other vegetables due to the strong bitter taste, although this can be moderated to some extent by salting and then washing the cut melon before use.
It is also a popular vegetable in Indian cooking, where it is often prepared with potatoes and served with yogurt on the side to offset the bitterness, or used in sabji. Bitter melon is stuffed with spices and then fried in oil, which is very popular in Punjabi Cuisine. It a popular food in Tamil Nadu and referred as பாகற்காய் (Pagarkai) slangly called as Pavakkai பாவக்காய். Bitter Gourd is popular in the cuisine of South Indian state of Kerala. They use it for making a dish called thoran mixed with grated coconut, theeyal and pachadi. This is one common medicinal food for diabetics. In Karnataka, the term used for bitter gourd is haagalakai (ಹಾಗಲಕಾಯಿ) and used in preparation of a delicacy called gojju (ಗೊಜ್ಜು).
Bitter melon is rarely used in mainland Japan, but is a significant component of Okinawan cuisine.
In Vietnam, raw bitter melon slices consumed with dried meat floss and stuffed to make bitter melon soup with shrimp are popular dishes. Bitter melons stuffed with ground pork are served as a popular summer soup in the South.
A very popular dish from the Ilocos region of the Philippines, pinakbet, consists mainly of bitter melons, eggplant, okra, string beans, tomatoes, lima beans, and other various regional vegetables stewed with a little bagoong-based stock.
The young shoots and leaves may also be eaten as greens; in the Philippines, where bitter melon leaves are commonly consumed, they are called dahon (leaves) ng ampalaya.
The seeds can also be eaten, and have a sweet taste; but are known to cause nausea.
In Nepal bitter melon is prepared in various ways. Most prepare it as fresh achar (a type of salsa). For this the bitter gourd is cut into cubes or slices and sautéed covered in little oil and a sprinkle of water. When it is softened and reduced, it is minced in a mortar with few cloves of garlic, salt and a red or green pepper. Another way is the sautéed version. In this, bitter gourd is cut in thin round slices or cubes and fried (sauted) with much less oil and some salt, cumin and red chili. It is fried until the vegetable softens with hints of golden brown. It is even prepared as a curry on its own, or with potato; and made as stuffed vegetables.
In Pakistan bitter melon is available in the summertime, and is cooked with lots of onions.
A traditional way to cook bitter melon curry is, to peel off the skin and cut into thin slices. It is salted and exposed to direct sunlight for few hours to reduce its bitterness. After few hours, it's salty, bitter water is reduced by squeezing out the excess by hand. Then it's rinsed with water a few times. Then fried in cooking oil, with onions also fried in another pan. When the onions have turned a little pink in color, the fried bitter melon is added to them. After some further frying of both the onions and bitter melon, red chili powder, turmeric powder, salt, coriander powder; and a pinch of cumin seeds are also added. A little water can be sprinkled while frying the spices to prevent burning. Then a good amount of tomato is added to the curry, with green chillies, according to taste. Now the pan is covered with a lid, heat reduced to minimum, the tomatoes reduce, and all the spices work their magic. The curry is stirred a few times (at intervals) during this covering period. After half an hour or so, the curry is ready to serve, with soft hot flat breads (chappatis, چپاتی) and yogurt chutney.
Another dish in Pakistan calls for whole, unpeeled bitter melon to be boiled and then stuffed with cooked ground beef. In this dish, it is recommended that the bitter melon be left 'debittered'. It is either served with hot tandoori bread, naan, chappati, or with khichri (a mixture of lentils and rice).
Bitter melons have been used in various Asian traditional medicine systems for a long time Like most bitter-tasting foods, bitter melon stimulates digestion. While this can be helpful in people with sluggish digestion, dyspepsia, and constipation, it can sometimes make heartburn and ulcers worse. The fact that bitter melon is also a demulcent and at least mild inflammation modulator, however, means that it rarely does have these negative effects, based on clinical experience and traditional reports.
Though it has been claimed that bitter melon’s bitterness comes from quinine, no evidence could be located supporting this claim. Bitter melon is traditionally regarded by Asians, as well as Panamanians and Colombians, as useful for preventing and treating malaria. Laboratory studies have confirmed that various species of bitter melon have anti-malarial activity, though human studies have not yet been published
Laboratory tests suggest that compounds in bitter melon might be effective for treating HIV infection As most compounds isolated from bitter melon that impact HIV have either been proteins or glycoproteins lectins), neither of which are well-absorbed, it is unlikely that oral intake of bitter melon will slow HIV in infected people. It is possible oral ingestion of bitter melon could offset negative effects of anti-HIV drugs, if a test tube study can be shown to be applicable to people In one preliminary clinical trial, an enema form of a bitter melon extract showed some benefits in people infected with HIV (Zhang 1992). Clearly more research is necessary before this could be recommended.
The other realm showing the most promise related to bitter melon is as an immunomodulator. One clinical trial found very limited evidence that bitter melon might improve immune cell function in people with cancer, but this needs to be verified and amplified in other research If proven correct this is another way bitter melon could help people infected with HIV.
Folk wisdom has it that ampalaya helps to prevent or counteract type-II diabetes, although outside of anecdotal stories scientific evidence for this claim is limited. Regardless of its efficacy in this regard, it is sold in the Philippines as a food supplement and elixir for this purpose. Studies so far demonstrate improvement but not cure in some diabetic parameters.
Bitter Melon contains four very promising bioactive compounds.
These compounds activate a protein called AMPK, which is well known for regulating fuel metabolism and enabling glucose uptake, processes which are impaired in diabetics.
("We can now understand at a molecular level why bitter melon works as a treatment for diabetes," said David James, director of the diabetes and obesity program at the Garvan Institute of Medical Research in Sydney.
"By isolating the compounds we believe to be therapeutic, we can investigate how they work together in our cells.")
Various cautions are indicated. The seeds contains vicine and therefore can trigger symptoms of favism in susceptible individuals. In addition, the red arils of the seeds are reported to be toxic to children, and the fruit is contraindicated during pregnancy.
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