Jackfruit

Jackfruit is an evergreen to semi-deciduous tree 10–20 m tall with a trunk 30–80 cm across; every part contains sticky, milky white latex. The leaves are simple and alternate, thick and glossy, ovate to elliptic, 8–25 cm long with entire margins, sometimes lobed when young; the stipules fall early and leave a ring scar around the stem. The tree is monoecious, with separate male and female flower heads borne directly on the trunk and old branches (cauliflory). The fruit is a syncarp and the largest tree-borne fruit: 30–90 cm long, 10–50 kg, with a rind covered in small polygonal green-yellow spines; inside are hundreds of sweet, fragrant orange-yellow bulbs, each enclosing a brown seed. The tree is evergreen and crops almost continuously in the tropics; grafted trees bear fruit in 3–5 years.

According to Kew's Plants of the World Online, the native range of Artocarpus heterophyllus is south-western India (the Western Ghats, in Kerala), in the wet tropics. The species has been cultivated and spread across South and Southeast Asia for thousands of years, with centres of cultivar diversity in India, Bangladesh, Thailand, Malaysia and Indonesia. Today jackfruit is also grown in Brazil, East Africa, the Caribbean and the Pacific islands. In Vietnam it is common in the Mekong Delta (Thai, Nai and To Nu cultivars), the south-east and the midland hills of the north.

Ripe jackfruit bulbs are rich in simple sugars (fructose, glucose) and sucrose, giving their deep sweetness, alongside carotenoids (β-carotene, provitamin A, the source of the orange-yellow colour), vitamin C, vitamin B6 and the minerals potassium, magnesium and calcium. Unripe fruit holds much starch and fibre and is milled into a nutritious flour. The most distinctive group are the prenylated flavonoids of the heartwood and bark — artocarpin, artocarpanone, norartocarpetin and morin — studied for antibacterial, anti-inflammatory and melanin-inhibiting effects. The seeds contain the characteristic lectin jacalin, a galactose-binding protein widely used in immunology, together with starch and lignans. The reviews by Baliga et al. (Food Research International, 2011) and by Jagtap & Bapat (Journal of Ethnopharmacology, 2010) systematise these groups.

Ripe jackfruit is eaten fresh or dried and made into ice cream, smoothies and preserves; unripe fruit is cooked in soups, salads and vegan braises or milled into flour; the seeds are boiled or roasted and eaten for their starch. The golden, durable, termite-resistant timber is used for furniture, carving and musical instruments, and the leaves serve as fodder. Pharmacologically, Fang et al. (Journal of Agricultural and Food Chemistry, 2008) isolated phenolic compounds from the fruit and demonstrated anti-inflammatory activity; Septama & Panichayupakaranant (Pharmaceutical Biology, 2015) showed that artocarpanone and other heartwood flavonoids are antibacterial against enteric pathogens; and the lectin jacalin was described by Kabir (Journal of Immunological Methods, 1998) for its many uses in immunological research.

On safety, ripe jackfruit flesh is a safe and nutritious food; however the latex can be sticky, irritate the skin and cause allergy in latex-sensitive people, so gloves are advisable when separating the bulbs. The seeds should be eaten only after boiling or roasting. Jackfruit is high in natural sugars, so people with diabetes should eat it in moderation. For conservation, the IUCN has not assessed the species (Not Evaluated) and it is not covered by CITES; although widely cultivated, wild populations in the Western Ghats of India are shrinking through forest loss and genetic erosion from cultivar selection. Conservation focuses on maintaining cultivar diversity and wild germplasm in gene banks.