Читать книгу Cucurbits - James R. Myers - Страница 25

The uses of cucurbits are diverse. Fruit may be eaten when immature (e.g. summer squash) or mature (watermelon). They are baked (squash), fried (bitter gourd), boiled (wax gourd, snake gourd), stuffed (stuffing cucumber), pickled (cucumber, pickling melon), candied (watermelon, squash, wax gourd, Malabar gourd), consumed fresh in salads (cucumber) or as a dessert (melon, watermelon). Fresh fruit are sold soon after harvest or following a storage period of several weeks to months. Processing for long-term storage often involves canning, freezing, or pickling (Fig. 2.1). Juice from cucumber fruit is used to make salad dressing, lotion and shampoo. Watermelon fruit juice is used directly as a fresh drink, but results in a ‘squash flavour’ when pasteurized. Juice from the fruit of watermelon, Malabar gourd and other cucurbits is fermented to make alcoholic beverages; for example, a liqueur is made from melon in Japan. Fruit are the most important plant part that is used. However, seeds (Cucurbita, Cucumeropsis and many others), roots (chayote), flowers (squash) and leaves and shoot tips (Telfairia, Momordica) also provide human sustenance.

Fig. 2.1. Pickled snake melon.

Seeds of watermelon, oyster nut, !nara and other cucurbits are an important part of the African diet. Watermelon seeds are used to make snacks, using the large (long) seed size (not the medium, short or tomato seed sizes), usually with a white seed coat. In Mexico and Central American countries, squash seeds are sold in stores and at street corners as snacks. The development of squash and pumpkin cultivars with ‘naked’ seeds, devoid of tough seed coats, has increased the popularity of squash seeds for food in other countries.

Cucurbits are used for other purposes besides food and drink. From bottle gourds, people have fashioned storage containers, bottles, cups, bowls, utensils, smoking pipes, musical instruments, penis sheaths, masks, floats for fishnets, rattles for babies and many other items. The dry fruit rinds of other cucurbits, including wax gourd, wild and cultivated species of Cucurbita and fluted pumpkin, sometimes serve as containers and utensils as well. The oils extracted from seeds of watermelon, squash, luffa, antidote vine, lard plant, white-seeded melon, colocynth and other cucurbits are prepared for cooking, illumination, candle and soap manufacture and industrial purposes. Colocynth seeds have 18% oil (70% of which is linoleic). The fibrovascular system of a mature luffa fruit provides a sponge suitable for various purposes, including use as a filter. Nigerians pound and work the thick stems of sponge plant to yield white, absorbent fibres that serve as a washing sponge. Stem fibres of fluted pumpkin are extracted for use as a sponge and for making rope. Jewellery is fashioned from seeds of various cucurbits (Cayaponia kathematophora, Marah species). Squash flowers are used in make-up and cucumber fruit extracts are added to soap and shampoo. Arabs employ the dried fruit pulp of colocynth in the making of gunpowder, tinder and fuses.

Medicinal applications of cucurbits are numerous. Since ancient times, indigenous cultures worldwide have employed cucurbits to treat ailments. A Chinese medicinal text written during the 1st century ad mentions the therapeutic benefits of wax gourd, pickling melon, bottle gourd and Japanese snake gourd. In modern Chinese commerce, he zi cao (Actinostemma lobatum), jiao-gu-lan (Gynostemma pentophyllum), luo-han-guo (Siraitia grosvenorii) and species of Trichosanthes are the most important medicinal cucurbits (Yang and Walters, 1992; Cai et al., 2004; Xu, 2017).

Some of the reported therapeutic properties, including the use of cucurbits as purgatives, emetics and anthelmintics (anti-parasite drugs), are due to cucurbitacins, which are bitter triterpenoid compounds known to have drastic effects on the digestive system. Cucurbitacins are present in almost all cucurbits, usually throughout the plant, but especially in fruit and roots. Other toxic and potentially medicinal compounds in cucurbits include saponins, free amino acids and alkaloids.

Cucurbit fruit, and their extracts, are the plant part most commonly prepared for medicine. The gourd-like fruit of colocynth is used as a purgative for constipation and parasitic worms, as an anti-tumour agent for cancer and as a remedy for fever, urogenital disorders and other problems. The bitter roots of many cucurbits (e.g. bryony) have cathartic effects as well. Leaves are employed for medicine less frequently, often dried and pounded into a powder or made into a tea (G. pentophyllum). Seeds of squash, wax gourd, bottle gourd and other cucurbits are taken as anthelmintic medicine. Oil extracted from seeds of antidote vine (Fevillea cordifolia) is used medicinally to counteract the poison of a snakebite, to ward off dandruff and for an assortment of other ailments.

One of the most widely employed of the medicinal cucurbits is bitter gourd. Research has shown that this plant serves to control, though not cure, mild to moderately chronic cases of diabetes mellitus by increasing carbohydrate utilization. Medical investigators in China, Japan and India are testing species of Momordica for their purported analgesic (pain relief), abortifacient (causing abortion), immunosuppressive and anti-tumour properties. Similar laboratory research is ongoing for species of Trichosanthes (Rai et al., 2009; Liyanage et al., 2016). In 1989, compound Q (related to methane monooxygenase), which is an active principle extracted from Chinese snake gourd, received a lot of attention when medical professionals began to study it as a treatment against the human immunodeficiency virus (HIV). Bitter gourd has also been used to combat HIV infection.

The bioactive compounds in cucurbits also serve other purposes. People in Mexico have long taken advantage of the saponins in fruit of wild Cucurbita for creating a frothy cleansing soap. Similarly, Nigerians use the leaves of balsam apple to clean metals, and the leaves and fruit as a body wash. Saponins in seeds and fruit make an effective component in fish poison. For example, luffa is used for that purpose in Australia. Fruit of casabanana are hung in the house as a room deodorizer. Various cucurbits are used to repel insects. The Chinese spray extracts of Luffa and Momordica on crops to control spider mites and other agricultural pests (Yang and Tang, 1988). In North Africa, Arabian camel herders smear a rind extract of colocynth on water bags to keep camels away.

Cucurbit fruit sometimes become objects of decoration and art. In the USA, ornamental gourds and turban squashes provide autumn table decorations, and pumpkins (C. pepo) are carved and illuminated with candles to celebrate the holiday of Halloween, as well as celebrations of autumn harvest. The ultimate degree of artistic expression has been reached with bottle gourds. Many different cultures independently developed the custom of carving, painting and otherwise decorating the gourds that were so useful to them. The art of gourd decoration is most highly developed in Peru, where detailed pyro-engraving techniques produce fine-art gourdcraft exported around the world.

Finally, some cucurbits are grown as ornamental plants. In addition to its lacy leaves and colourful fruit, the fragrant blossoms of bitter gourd make this species a very appealing trellis ornamental. Bitter gourd has been grown in glasshouses in the UK since Victorian times. The beautiful white, fringed petals of snake gourd and its long serpent-like fruit, dangling beneath a garden arbour, make for a picturesque sight. The spiny fruit of teasel gourd and African horned melon and the explosive fruit of squirting and exploding cucumbers have brought these cucurbits into commercial trade as well. The most recent horticultural trend affecting cucurbits is the passion for succulents. Collectors are beginning to learn of and trade among themselves the caudiciform cucurbits of Africa (e.g. Gerrardanthus and Trochomeria), Madagascar (Seyrigia and Xerosicyos) and North America (Marah and Ibervillea).