Gac (Momordica cochinchinensis) is found throughout the Southeast Asian region from South China to Northeastern Australia. Gac is notable for its densely orange fruit containing rich contents of beta-carotene and lycopene.
It is commonly known as gac from the Vietnamese gấc (pronounced [ɣək˦˥]) or quả gấc (quả being a classifier for spherical objects such as fruit). It is known as red melon, baby jackfruit, spiny bitter gourd, sweet gourd, or cochinchin gourd in English.
The fruit itself becomes a dark orange color upon ripening, and is typically round or oblong, maturing to a size of about 13 cm (5.1 in) in length and 10 cm (3.9 in) in diameter. Its exocarp, or exterior skin, is covered in small spines. Its mesocarp is dense, light-orange in color, and has a mild taste with flavor similar to that of cucumber. The edible seeds are brown or black in color, surrounded by dark red membraneous sacs, and have a mild, nutty flavor.
Because it has a relatively short harvest season (which peaks in December and January), making it less abundant than other foods, gac is typically served at ceremonial or festive occasions in Vietnam, such as Tết (the Vietnamese new year) and weddings. It is most commonly prepared as a dish called xôi gấc, in which the aril and seeds of the fruit are cooked in glutinous rice, imparting both their color and flavor. More recently, the fruit has begun to be marketed outside of Asia in the form of juice or dietary supplements because of its rich carotenoid content.
Gac grows on dioecious vines, meaning male and female flowers grow on separate plants. The vine is usually collected from fence climbers or from wild plants, and can be commonly seen growing on lattices at the entrances to rural homes or in gardens. The vine can grow up to 20 m (66 ft) in length and the bark is a pale color. It only fruits once a year, and is found seasonally in local markets.
Rooted vine cuttings are more reliable than production from seeds. Germination by seed can be difficult due to many environmental factors such as dormancy, climate, or plant age. A successful alternative method is grafting female scion material onto the main shoot of an unwanted male plant, therefore making it productive.
About two to three months after planting a gac vine, flowering typically occurs, with pollination carried out by insects or hand pollination which produces a higher fruit yield. One plant can produce 30 to 60 fruits in one season although environmental factors can affect that.
Historically, gac has been used as both food and traditional medicine. Other than the use of its fruit and leaves for special Vietnamese culinary dishes, gac is also used for its medicinal and nutritional properties. In Vietnam, the seed membranes are said to aid in the relief of dry eyes, as well as to promote healthy vision. Similarly, in traditional Chinese medicine the seeds of gac, known in Mandarin Chinese as mù biē zǐ (Chinese: 木 鳖 子 meaning 'wooden turtle seed'), are employed for a variety of internal and external purposes.
Typical of orange-colored plant foods, gac fruit and seed oil contain high contents of carotenoids, particularly provitamin A beta-carotene and lycopene. Fatty acids in the seed oil may facilitate absorption of fat-soluble nutrients, including provitamin A beta-carotene.
Marketed on its high content of beta-carotene and lycopene, gac extracts may be sold as a dietary supplement in soft capsules or included in a juice blend. Vietnamese children fed a rice dish containing gac had higher blood levels of beta-carotene than those not fed gac.