Siam Villa Garden: Bilimbi or Tree Sorrel

Averrhoa bilimbi is a small tropical tree native to Malaysia and Indonesia, reaching up to 15m in height. It is often multitrunked, quickly dividing into ramifications. Bilimbi leaves are alternate, pinnate, measuring approximately 30–60 cm in length. Each leaf contains 11-37 leaflets; ovate to oblong, 2–10 cm long and 1–2 cm wide and cluster at branch extremities. The leaves are quite similar to those of the Otaheite gooseberry. The tree is cauliflorous with 18–68 flowers in panicles that form on the trunk and other branches. The flowers are heterotristylous, borne in a pendulous panicle inflorescence. There flower is fragrant, corolla of 5 petals 10–30 mm long, yellowish green to reddish purple. The fruit is ellipsoidal, elongated, measuring about 4 – 10 cm and sometimes faintly 5-angled. The skin, smooth to slightly bumpy, thin and waxy turning from light green to yellowish-green when ripe. The flesh is crisp and the juice is sour and extremely acidic and therefore not typically consumed as fresh fruit by itself. Fruit is often preserved and used as a popular flavouring/seasoning and is a key ingredient in many Indonesian dishes such as sambal belimbing wuluh and asam sunti (see Culinary interest). A. bilimbi holds great value in complementary medicine (see Medical interest) as evidenced by the substantial amount of research on it. According to traditional Indonesian/Malaysian knowledge, the trunk and branches of tree require exposure to sunlight to initiate flowering/fruiting, which can be assisted by removing leaves from the inner canopy.

In Indonesia, A. bilimbi, locally known as belimbing wuluh, is often used to give sour or an acidic flavor to food, substituting tamarind or tomato. In the north western province of Aceh, it is preserved by salting and sun-drying to make asam sunti, a kitchen seasoning to make a variety of Acehnese dishes.

In the Philippines, where it is commonly found in backyards, the fruits are eaten either raw or dipped in rock salt. It can be either curried or added as a souring agent for common Filipino dishes such as sinigang, pinangat and paksiw. It is being sun-dried for preservation. It is also used to make salad mixed with tomatoes, chopped onions with soy sauce as dressing.

The uncooked bilimbi is prepared as relish and served with rice and beans in Costa Rica.

In the Far East, where the tree originated, it is sometimes added to curry.

In Malaysia, it also is made into a rather sweet jam.

In Kerala and Bhatkal, India, it is used for making pickles and to make fish curry, especially with sardines, while around Karnataka, Maharashtra and Goa the fruit is commonly eaten raw with salt and spice. In Guyana and Mauritius, it is made into achars/pickles.

In Maldives where it is known as bilimagu, it is pickled with aromatic spices and eaten with rice and local Garudhiya (fish soup). It is also used in various Maldivian local dishes such as Boakibaa and Mashuni as a souring agent.

In Seychelles, it is often used as an ingredient to give a tangy flavor to many Seychellois creole dishes, especially fish dishes. It is often used in grilled fish and also (almost always) in a shark meat dish, called satini reken. It is also cooked down with onion, tomato, and chili peppers to make a sauce. Sometimes they are cured with salt to be used when they are out of season.

Bilimbi juice (with a pH of about 4.47) is made into a cooling beverage. It can replace mango in making chutney. Additionally, the fruit can be preserved by pickling,[9] which reduces its acidity.