Tara spinosa, commonly known as tara, is a small leguminous tree or thorny shrub native to Peru. T. spinosa is cultivated as a source of tannins based on a galloylated quinic acid structure. This chemical structure has been confirmed also by LC-MS. It is also grown as an ornamental plant because of its large colorful flowers and pods.
Names and taxonomy
Its common names include spiny holdback, tara, taya, and algarroba tanino. T. spinosa is placed in the family Fabaceae, subfamily Caesalpinioideae, and tribe Caesalpinieae.
Description
T. spinosa typically grows 2–5 m tall; its bark is dark gray with scattered prickles and hairy twigs. Leaves are alternate, evergreen, lacking stipules, bipinnate, and lacking petiolar and rachis glands. Leaves consist of three to 10 pairs of primary leaflets under 8 cm in length, and five to seven pairs of subsessile elliptic secondary leaflets, each about 1.5–4 cm long. Inflorescences are 15–20 cm long terminal racemes, many flowered and covered in tiny hairs. Flowers are yellow to orange with 6- to 7-mm petals; the lowest sepal is boat-shaped with many long marginal teeth; stamens are yellow, irregular in length and barely protruding. The fruit is a flat, oblong indehiscentpod, about 6–12 cm long and 2.5 cm wide, containing four to seven round black seeds, which redden when mature.
Distribution and habitat
T. spinosa is native to Peru and can be found growing throughout northern, western, and southern South America, from Venezuela to Argentina. It has been introduced in drier parts of Asia, the Middle East, and Africa and has become naturalized in California. T. spinosa grows in the nearly rainless lomas or fog oases of the Peruvian coastal desert. Generally resistant to most pathogens and pests, it grows at elevations between 0 and 3,000 m above sea level, and tolerates dry climates and poor soils, including those high in sand and rocks. To propagate, seeds must be scarified, and young plants should be transplanted to the fieldat 40 cm in height; trees begin to produce after 4–5 years. Mature pods are usually harvested by hand and typically sun dried before processing. If well irrigated, trees can continue to produce for another 80 years, though their highest production is between 15 and 65 years of age.
Uses
Industrial
T. spinosa pods are an excellent source of environmentally friendly tannins most commonly used in the manufacture of automotive and furniture leathers. This growing industry is developing around their production in Peru. Some producers have their own plantations to guarantee constant quality. Tara tannin derivatives are being proposed as antifouling against marine organisms that can grow on ship hulls. Those tannins are of the hydrolysable type. Gallic acid is the main constituent of tara tannins and can be easily isolated by alkaline hydrolysis of the plant extract. Quinic acid is also a constituent of the tara tannins. Its tannines are colourless or light making them suitable a premordant in the dyeing of cotton and other cellulose fibres. The tree can also be a source of lumber and firewood, and as a live fence. The seeds can be used to produce black dye, while dark blue dye can be obtained from the roots.
Food additive
Tara gum is a white or beige, nearly odorless powder that is produced by separating and grinding the endosperm of T. spinosa seeds. Tara gum consists of a linear main chain of -β-D-mannopyranose units attached by linkages with α-D-galactopyranose units. The major component of the gum is a galactomannanpolymer similar to the main components of guar and locust bean gums that are used widely in the food industry. The ratio of mannose to galactose in tara gum is 3:1. Tara gum has been deemed safe for human consumption as a food additive. Tara gum is used as a thickening agent and stabilizer in a number of food applications. A solution of tara gum is less viscous than a guar gum solution of the same concentration, but more viscous than a solution of locust bean gum. Generally, tara gum presents a viscosity around 5,500 cps. Furthermore, tara gum shows an intermediate acid stability between locust bean gum and guar gum. It resists the depolymerisation effect of organic acids down to a pH of 3.5. This gum is also stable to high-temperature treatment, up to 145 °C in a continuous process plant. Blends of tara with modified and unmodified starches can be produced which have enhanced stabilization and emulsification properties, and these are used in the preparation of convenience foods, such as ice cream. One example is the American ice cream brand Breyers. The European food additive number for tara gum is E417. Tara gum is listed on the Canadian List of Permitted Emulsifying, Gelling, Stabilizing or Thickening Agents as item T.2B. The Italian company Silvateam is a producer of tara gum for the food and beverage industries. Silvateam's website uses Caesalpinia spinosa as the Latin name of the plant, and notes that it is also called Peruvian carob. Silvateam encourages the use of tara gum in ice cream to provide "freeze-thaw stability by preventing the formation of ice crystals".
Medicinal
Medicinal uses in Peru include gargling infusions of the pods for inflamed tonsils or washing wounds; it is also used for fevers, colds, and stomach aches. Water from boiled, dried pods is also used to kill fleas and other insects.
