Gac fruit, a plant genetic resource with high potential

Gac is a fruit (Momordica cochinchinensis) which is found throughout the Southeast Asian region. It is commonly known as gac from the Vietnamese term gac (i.e. a spherical object). Gac plant grows as dioecious vines, in other words, male and female flowers are borne on separate plants, and produce flowers typically 5-10 cm in length, seasonally, solitary or in bundle. The vine can grow up to 20m long. Rooted vine cuttings are more reliable than seedling production from seeds, since germination by seed can be very difficult due to many environmental factors such as dormancy or plant age. An alternative method is to graft female scion material onto the main shoot of a male plant, thus making it productive. Flowering occurs about 2 to 3 months after planting a vine. The fruit is typically round or oblong, about 13 cm in length and 10 cm in diameter, and gradually becomes dark red colour upon ripening. Pollination may be assisted by insects, but hand pollination results in a higher fruit yield. A plant can produce 30 to 60 fruits in one season. Fruit colour progressively change from green to yellow, orange and finally red. The fruit is hard at harvest but rapidly turns soft, therefore poses problems with regard to transportation and shelf-life. Its exocarp (skin) is covered with small spines while its flesh (mesocarp) is dense and light-orange in colour. The seeds are usually brown or black in colour, surrounded by dark red membraneous sacs (aril). Gac fruit has a mild taste, or more accurately a rather flat taste to many people. Traditionally, Gac fruit has been grown for its medicinal and nutritional properties. In Vietnam, gac fruit is served at ceremonial or festive occasions and weddings. The aril and seeds of the fruit are usually cooked in glutinous rice to impart both their colour and flavour. Due to its high content of beta-carotene (provitamin A) and lycopene, the fruit has begun to be commercially marketed in the form of dietary supplements such as Gac extracts in soft capsules or included in a juice blend.