Gac

Gac, from the Vietnamese gấc, scientific name Momordica cochinchinensis, is a species of plant in the melon and cucumber family Cucurbitaceae which is native to countries throughout Southeast Asia and to Queensland, Australia. It is notable for its vivid orange-reddish color resulting from its rich content of beta-carotene and lycopene.

Description
Momordica cochinchinensis is a perennial tendril climber which may reach up to 15 m long and a stem diameter up to 4 cm. The palmate leaves have 3 to 5 lobes and are carried on a petiole (leaf stem) measuring 6 - 10 cm long. They are arranged alternately on the stems and measure up to 20 cm wide and long.

This species is dioecious, meaning that male and female flowers are borne on separate plants. The inflorescence on a male plant consists of either a solitary flower or a raceme up to 10 cm long, while female flowers are solitary. All flower buds are fully enclosed by bracts, which split open as the flower matures. The mature flowers have five yellowish petals and a black centre.

The fruit are ovoid to broadly ellipsoid, about 15 cm long by 10 cm diameter, and are covered with numerous small spines on the skin. They are initially green but turn a deep orange/red at maturity, and they contain numerous irregularly-shaped brown or grey seeds which are enclosed in a bright red aril.

Phenology
In the northern hemisphere this species flowers from June to August and fruit appear around August to October. In Australia, flowering occurs from December to January and fruit appear from February to April.

Phytochemistry
The fruit, seeds, and seed oil contain substantial amounts of beta-carotene and lycopene which collectively impart the characteristic red-orange color to the fruit's tissues. Both aril and seeds are rich in monounsaturated and polyunsaturated fatty acids, with oil containing 69% unsaturated fats, including 35% as polyunsaturated fats. Gac has a high concentration of linoleic acid (omega-6) and omega-3 fatty acids.

Taxonomy
This species was first described in 1790 by the Portuguese botanist João de Loureiro, who published it in his book Flora cochinchinensis. Loureiro gave this plant the combination Muricia cochinchinensis and noted that it was found in "Cochinchinâ, & Chinâ." In 1826 the German botanist Kurt Polycarp Joachim Sprengel transferred the species to the genus Momordica.

Etymology
The genus name Momordica is derived from the Latin word mordeo meaning to bite, a reference to the seeds' appearance as though chewed. The species epithet cochinchinensis means "from Cochinchina", the region in the southern part of Vietnam where the plant was first observed by Loureiro.

Common names
As this plant is native to many countries throughout the Asia-Pacific region, it has a diverse number of common names including: bhat kerala (Assamese), mu bie gua, mu bie zi and teng tong (Chinese), balsam pear, Chinese cucumber, and giant spiny gourd (English), kakur, kantola and kakrol (Hindi), tepurang (Indonesian), mokube tsushi (Japanese), makkao (Khmer), khaawz (Laotian), pupia, teruah and torobuk (Malay), jhuse karelaa (Nepalese), pakurebu (Sulawesi), buyok buyok (Tagalog), phak khao (Thai), and gac (Vietnamese).

Cultivation
As gac plant is dioecious, both male and female plants are needed; hence, farmers must have at least one corresponding male plant growing in or around the gardens for the fruit-bearing female plants to be pollinated. When grown from seed, the ratio of male to female plants is unpredictable.

Pollination may be facilitated by insects, but hand pollination allows for better fruit yield. An alternative method is to graft female material onto the main shoot of a male plant.

For maximum insect-aided pollination, the recommended ratio is about 1 male for every 10 female plants. If propagating from vines, farmers make diagonal cut (around 15-20 cm long and 3-6 mm wide), then root the tubers in water or well-aerated, moist potting media before planting.

Apart from Southeast Asian countries where the fruits are native, gac can be grown in sub-tropical climate regions. Cool temperatures inhibit growth.

Uses
Gac has been commonly used in its native countries, mainly as food and traditional medicine. Its use as a folk medicine dates back over centuries in China and Vietnam. Gac seeds, known as   (meaning 'wooden turtle seed'), are used for a variety of internal and topical purposes in traditional medicine.

The aril surrounding gac seeds when the fruits are ripe is cooked with sticky rice to make xôi gac, a traditional Vietnamese dish in red color served at weddings and New Year celebrations. In addition, the immature green fruit is also used as a vegetable in India. The spiny skin is removed and the fruits are sliced and cooked sometimes with potato or bottle gourd. In Sri Lanka, gac is used in curry, and in Thailand, gac is served with ice cream.

Due to the high contents of beta-carotene and lycopene, extracts from the fruit's arils are used to manufacture dietary supplements in soft capsules or are sometimes mixed into beverages.