The opo squash is a squash species of Asian origin, with the scientific name Lagenaria siceraria. It is a member of the Cucurbitaceae family. Opo squash is cooked similar to summer squashes, even if botanically it is actually a gourd. The species is classified as a calabash type and has the alternative name of summer squash in some areas where it is cultivated. Other names are the snake gourd and the Tasmanian bean. The Chinese name it simply the opo but the varieties covered by hairs are also known as hulu or moa gua.
This squash is easy to identify due to the distinctive long cylindrical shape. It can grow to a length between 10 and 15 inches before it is harvested. The skin is typically smooth, with a green color, while the flesh is white, with a soft texture. The small seeds are soft and edible when young but they have to be removed later because they can become very hard and can no longer be consumed. The flesh of the opo squash is tender but firm at the same time. It has a mild taste that has been described as a mix of cucumber and summer squash.
The opo squash is a vine with an annual growth cycle that can climb very fast. In order to produce flowers and fruits, it needs plenty of sunlight. Trellis support is required for a proper spread but otherwise it tolerates a variety of soils.
If they have enough space, the stems will expand into many branches. The green broad leaves with a musky appearance resemble the ones of pumpkins. During the summer, a large number of white flowers appear, of a monoecious type. The plant needs about 75 days in total until the first edible fruits with a tender flesh can be harvested.
Opo cultivars come in a variety of different sizes and shapes. The fruits normally have a light green color and smooth skin, with a shape that can be oval or pear-shaped. The round or pear-shaped squashes usually have discrete ridges along their entire length. The flesh is soft and white, with a spongy or creamy texture. The small seeds are initially soft, they later grow to the same size as the ones of honeydew melons. If the climate is right, opo squashes can be cultivated the entire year.
While young fruits are an important food source, the mature opo squash has many others uses. Dried fruits are employed in various roles all across Asia. Chinese people have always associated it with good health and it is said to be able to deflect negative energies and protect people from their effects. In old China, doctors used dried squashes as a sort of bag where they carried other medicine. Opo squashes were also forced to grow in special shapes using molds. Once dried, they were artistically decorated and used as small cricket houses. This practice had two advantages: it provided natural shelter for the insects and the hollow interior amplified their songs, similar to a musical instrument. The dried opo squash was actually used for this purpose in India, in the manufacture of sitars and other instruments. The opo squash is known as the kamandalu in India, where it serves as a traditional vessel in Hindu ceremonies.
The opo and other related calabash squashes have been domesticated in Africa more than 10000 years ago. This fact makes it one of the oldest plants cultivated by humans. Ancient people took the seeds with them during their migrations, so the Opo is found today all over the world. It has various names, depending on the location. Opo is the Chinese name of the squash and has become accepted in many other places due to the influence of Chinese cuisine. It is sold under this name in restaurants, Oriental markets and specialized Asian shops. People of the Philippines have named it the Upo, Japanese people named it Yugao while Koreans designate it as Bak.
Calabash squashes like the opo need a long warm season in order to produce fruits. These are very large in size, so the plant must be placed on a trellis or another type of support. This is very important; otherwise the squashes will touch the ground and are unable to grow straight.
The opo squash is ideal for weight loss diets due to the very low content of calories. At the same time, it is packed with nutrients like folate, vitamins B and C, calcium, iron and zinc. It is beneficial for digestion due to the content of digestive fibers. The juice is valuable for the ability to regulate blood glucose levels, as well as a source of zinc and vitamin C. It is consumed as a healthy beverage in India. However, if the juice has turned bitter, it should be discarded. This is a sign that it has become toxic and is no longer fit for consumption. The juice that isn't fresh can contain compounds that hurt the intestines and can even be lethal in some cases.
The opo squash provides just 14 calories in a serving of 100 grams, which makes it one of the vegetables with the lowest calories content. As a result, specialists often recommend it for weight loss diets.
One important nutrient found in small amounts in the opo squash is folate. A serving supplies just 1.5% of the daily recommended amount. This compound is very important for mothers in their first weeks of pregnancy, because it prevents neural tube defects in infants.
Opo squashed provide a limited amount of vitamin C when fresh, with 10 mg or 17% of the required daily intake found in a serving of 100 grams. This compound has many uses but it is best known for its antioxidant actions. It destroys the toxic chemicals named free radicals that trigger cell mutations and are one of the causes of cancer. Vitamin C is also a very effective booster of the immune system and makes it more resilient against pathogens.
Including opo squashes in your diet can improve digestion due to the content of dietary fibers. Fibers can prevent constipation and indigestion by regulating the movement of food through the intestinal tract.
Fresh squashes also supply other nutrients, even if the amounts are quite low. They provide minerals like potassium, manganese, magnesium, calcium, iron and zinc, as well as the vitamins niacin (vitamin B 3), pantothenic acid (vitamin B 5), pyridoxine (vitamin B 6) and thiamine (vitamin B1).
When the plant is young, its tendrils and leaves can also be consumed. They are actually richer in vitamins and minerals than the mature fruit.
Most gourd species are edible but many varieties, like the zucchini, can only be consumed when young. There are also inedible gourds, with a very bitter taste. Mature gourds no longer have pulp, which dries out leaving just a hard outer shell and the seeds inside. Fully developed shells are waterproof and can be used for various purposes when dried. They have been used to manufacture containers like bowls or water jugs, as well as cups, fish nets, music instruments, tribal decorative items or smoking pipes.
The opo squash is cultivated primarily for its edible fruit. Young squashes have soft skin and are usually eaten whole, the skin remains edible when they mature but it can be discarded because it has a harder texture. The young fruits can replace zucchinis in most recipes.
Squash cubes are very popular in Chinese cuisine and they are mixed in fritters and quick breads or added as ingredients in stews, stir-fries and soups. Older fruits are turned into puree or roasted and then included in soups or sauces. Another very common dish consists of baked or steamed hollow opo squashes, with various fillings. They can be combined with sausages, seafood and pork meat, as well as other vegetables like bitter greens, onion, spicy peppers, ginger, garlic, soy sauce, coconut milk, eggplant or cabbage. Dry squashes can be stored for two or three weeks in the fridge.
Even if Lagenaria siceraria is usually associated with Asia today, the species is probably native to Africa. It has been carried away by humans since ancient times and cultivated in various warm areas of the world.
Seeds are viable and offer an easy way to propagate this annual vine. After the last spring frost, the seeds can be planted in the ground as soon as temperatures reach 70 degrees F. They are best grouped in small mounds, the spacing depends on the availability of supports. About 3 inches between mounds are needed when cultivated on supports, additional spacing up to 6 inches is needed otherwise. In order to produce fruits that ripen properly, the vines need a long warm growth season. You can give them a head start by growing them indoors in small pots, after spring starts. They enjoy full sun exposure and soils with good drainage, with a content of sand or loam. They tolerate afternoon shade. Opo squashes need plenty of water for the best production results.
The flowers open during the night and can be pollinated by hand in order to yield more fruits. They enjoy long summers, with hot temperatures and a lot of humidity. Opo plants are usually grown on supports but can also spread on the ground, covering a lot of space. Fruits grown for decorative purposes are always cultivated on supports, it is very important not to allow them to touch the ground in order to preserve a straight shape. Squashes are harvested in the autumn and a short section of stem is usually sectioned with the fruit.