Microsoft Word Asian vegetables Progress in New Crops 1996. doc
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| ASIAN CUCURBITS
Bitter melon (Momordica charantia L.) Bitter melon is a cucurbit vine native to Asia with eastern India and southern China proposed as the centers of domestication (Yang and Walters 1992). It is now widely cultivated throughout the world for the immature fruits, and sometimes for the tender leafy shoots or the ripe fruits. Other species used for their immature fruits in a similar way are M. cochinchinensis and M. dioica. The immature fruits are stuffed, pickled, and sliced into various dishes. The immature fruits, called bitter melon, bitter gourd, or balsam pear, are harvested at developmental stages up to seed hardening; the fruits are warty in appearance and vary in size from 12 to 30 cm long. The bitter melon vine is a rapidly growing monoecious herbaceous vine ( Fig. 1
) which needs to be trellised. Bitter melon is best adapted to hot to moderate climates and grows well in a variety of soils. Flowering begins about 1 month after seed planting. A fruit fly (Strumetia cucurbitae) attacks the fruit in some production areas, and the fruit are covered with paper protective bags. Fruits can be harvested at any stage of development, but are typically harvested fully sized but green, about 2 weeks after anthesis ( Fig. 2 ).
There are three horticultural groups or types of bitter melons (Yang and Walters 1992): (1) small fruit type, 10-20 cm long, 0.1-0.3 kg in weight, usually dark green, fruit are very bitter; (2) long fruit type, type most commonly grown commercially in China, 30-60 cm long, 0.2-0.6 kg in weight, light green in color with medium size protuberances, and only slightly bitter; and (3) triangular fruit type, cone-shaped, 9-12 cm long, 0.3-0.6 kg in weight, light to dark green with prominent tubercles, moderately to strongly bitter. The bitter principle, for which the fruit is named, is due to the alkaloid momordicine, not to cucurbitacins as in other members of the Cucurbitaceae. Immature fruits are less bitter than the mature but unripe fruits. Among the different types of bitter melons, smaller darker green types are very bitter, and the lighter green-colored fruit are slightly bitter. Bitter melon is also important for various medicinal properties (Morton 1967), with more recent attention focused on it as a hypoglycemic agent (Perl 1988). The spongy white interior pulp and seeds of unpeeled immature bitter melon are sliced for use as a vegetable in various Asian dishes. The fruit are parboiled or soaked in salted water to remove excessive bitter principle. Proximate composition is similar to that of other immature cucurbit fruits (
Table 1 ).
Good quality bitter melon should have a fresh appearance and the peel should be of uniform green color and free from visual defects. The developing fruit should be firm without excessive seed development, and free of defects such as decay and splitting, both associated with fruit ripening. When the fruit begins to ripen, the exterior color changes from green to yellow and the pulp becomes gelatinous and orange-red ( Fig. 3
). Contary to other cucurbits, the seed arils also change color from white-cream to a bright red. Among the more than 14 carotenoids identified during the ripening process, the principal carotenoid is cryptoxanthin (Rodriguez et al. 1976). Coincident with color changes, the fruit pulp loses bitterness and becomes sweet. The bitter melon is harvested, selected for size and uniformity of fruit surface characteristics and commonly packed in carton or wood boxes containing 5, 10, or 20 kg. It is a chilling sensitive vegetable, and may be air-cooled to 10° to 12°C (Zong et al. 1995). Less commonly, the bitter melon is harvested, hydrocooled and treated with a postharvest fungicide. Bitter melon are intermediate in perishability among vegetable crops ( Table 2
, 3 , 4 ).
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