About Acmella oleracea (L.) R.K.Jansen
Acmella oleracea (L.) R.K.Jansen is a species of flowering herb in the family Asteraceae. Its common names include toothache plant, Szechuan buttons, paracress, jambu, buzz buttons, tingflowers and electric daisy. While its native distribution is unclear, it is most likely derived from a Brazilian Acmella species. It is a small, erect quick-growing plant that produces gold and red inflorescences. It is sensitive to frost, but grows as a perennial in warmer climates. Its specific epithet oleracea comes from Latin, where it means "vegetable/herbal", and is a form of the word holeraceus (oleraceus).
For culinary use, small amounts of shredded fresh leaves are reported to add a unique flavor to salads. Cooked leaves lose their strong flavor and can be used as leafy greens; both raw leaves and the plant's fruit are edible. Young cooked branches are also safe to eat. In Madagascar, the plant is called anamalaho (known as brède mafane in Réunion Creole), and it is a main ingredient in the island's national dish romazava. Both fresh and cooked leaves are used in dishes including the stew tacacá from northern Brazil, particularly in the state of Pará. These leaves are combined with chilis and garlic to add flavor and vitamins to other foods.
The plant's flower bud has a grassy taste followed by a strong tingling or numbing sensation, often triggers excessive salivation, and leaves a cooling sensation in the throat. The buds are referred to as "buzz buttons", "Sichuan buttons", "sansho buttons", and "electric buttons". In India, the buds are used as a flavoring in chewing tobacco. A concentrated extract from the plant, often called jambu oil or jambu extract, is used as a flavoring agent in foods, chewing gum, and chewing tobacco. This oil is traditionally extracted from all parts of the plant. Both the European Food Safety Authority (EFSA) and the Joint FAO/WHO Expert Committee on Food Additives (JECFA) reviewed a rat feeding study. Both authorities identified a no adverse effect level of 572 mg/kg body weight per day for spilanthol, which gives a safe daily dose of 1.9 mg of spilanthol per kg of body weight. This equals 133.5 mg per day for a 70 kg male, 111 mg per day for a 58 kg female, and 38 mg per day for a 20 kg child.
As a flavoring agent, jambu extract has an odor described as citrus, herbal, tropical or musty, and its taste can be characterized as pungent, cooling, tingling, numbing, or effervescent. Spilanthol, the primary constituent of jambu extract, causes the perceived mouth-watering flavor sensation, and acts as a sialogogue to promote salivation. This sialogogue effect may occur through spilanthol's astringent action or its pungent taste.
For cultivation, this plant prefers well-drained, black soil with high organic content. If seeds are sown directly outdoors, they must not be exposed to cold weather, so sowing should be done after the last frost of the season. Seeds require direct sunlight to germinate, so they should not be buried in soil. A decoction or infusion made from the plant's leaves and flowers has been used as a folk remedy.
