Root crops (NRI, 1987, 308 p.)[edit | edit source]
Shoti (Curcuma zedoario)[edit | edit source]
Curcuma zedoario (Berg.) Roscoe.
Indian arrowroot, Kachoor, Kachora, Kunchur, Palagunda, Palua (Ind.); Temu kuning (Mal.); Temu puteh (Indon.); Zadwar (Ar.); Zï¿½doaire (Fr.); Zedoarwurzel, Zittwer ku-kume (Ger.).
Shoti is a robust perennial with fleshy, branching rhizomes; leafy or flowering shoots arise from the ends of the rhizome branches. The leafy shoots are up to 1 m tall and consist of a pseudostem of closely compacted concentric leaf bases, with the true stem extending for only part of the way within. Each shoot has about 5 leaves, in two rows on opposite sides of the shoot. The leaf blades are elongated-elliptical, about 35 x 13 cm, with a purple band on each side of the midrib when young, and with close parallel-pinnate veins, usually brownish. The flowers are pale-yellow, borne on spikes about 15 cm tall, in clusters of 4 or 5 in the axils of bracts which are green at the lower end of the spike, tipped with purple in the middle region, and entirely purple at the uppermost end. At the base of each aerial stem is an ovoid tuber which bears several short, thick, horizontal rhizomes and also tuberous roots.
Origin and distribution
The origin of shoti has never been precisely determined, although northeastern India has been considered by some authorities as the most likely area. It has been in cultivation since prehistoric times and has been spread and become naturalised throughout the rest of India, South-East Asia, southern China, Sri Lanka, Indonesia and the Philippines. Shoti seldom flowers in cultivation, but does so freely when it 'runs wild'.
The plant requires a hot, humid climate with an annual rainfall of 90-125 cm, and grows from sea level to about 1 000 m in the tropics. Forest is the natural habitat, and when cultivated it is usually shaded (eg in areca nut gardens).
Soil - for optimum yields loamy well-cultivated soils are required, but in Bengal shoti is reported to grow successfully on badly-drained sandy soils where many other crops may fail. The application of 25 t/ha of FYM has been recommended, followed by the application of 340 kg/ha of ammonium sulphate, 450 kg/ha of superphosphate and 450 kg/ha of potassium muriate in two doses, one 40 days after planting and the other after 180 days.
Material - propagation is vegetative and usually the mother rhizomes are used; if the daughter or finger rhizomes are used or pieces of rhizome with growth buds, then yields are considerably reduced.
Method - in India germination of the rhizomes is often started in well-manured, hand-watered, shaded, nursery beds during February or March. After germination has started, the rhizomes are planted out in the field at the beginning of the rainy season (June/July). Planting on flat beds, which are subsequently earthed up into ridges after the second application of fertiliser, gives better results than planting in ridges or on flat beds. After planting in the field the crop usually receives a thick mulch and is kept free from weeds.
Field spacing - the recommended spacing is 22-45 cm within and between rows
Seed rate - 1 100 kg of rhizomes are required to plant one hectare.
Shoti normally takes about 10 months to produce a crop.
Harvesting and handling
The crop is usually dug by hand when the leaves begin to wither. The finger rhizomes are carefully separated from the mother rhizomes, which are used for replanting.
Rhizomes - the starchy finger rhizomes are greyish in colour externally and have yellowish-white flesh, darkening in the centre with age to a honey-brown colour. They usually grow to about 15 cm in length and about
2.5 cm thick and have a rather musky odour, with a camphoraceous note and a pungent bitter taste.
In Orissa, India, yields are reported to average 7.5-12 t/ha.
Shoti is used mainly as a source of an easily-digested starch, which is rather similar to that of arrowroot, and is utilised in India on a cottage industry basis for the preparation of invalid and baby foods.
The tuberous rhizomes of wild plants are eaten, after washing, in times of food scarcity. The tubers have been sliced and dried and exported from India in the form of chips for the preparation of starch.
Secondary and waste products
The rhizomes are also used for medicinal purposes and in the manufacture of perfumes and cosmetics in India. Steam distillation of the rhizomes yields 1-2 per cent of a light-yellow essential oil and during the 9th to 13th centuries they were shipped to Europe for the extraction of this oil. The leaves are sometimes used for culinary purposes, especially for cooking fish, and the tender young buds may form an ingredient for salads.
An analysis of the rhizomes has been given as: water 69-70 per cent; starch 12-13 per cent; fibre 18-19 per cent. The starch grains have an average size of 1.6-4.2 microns and are elongated or ovoid in shape, closely resembling those of arrowroot. An analysis of a commercial sample of Indian shoti starch gave: water 13.1 per cent; starch 82.6 per cent; ash 1.01 per cent. The starch had 31.3 per cent amylose content. Shoti starch is readily hydrolysed by acids and possesses a high viscosity similar to potato starch. A sample of the essential oil extracted from the rhizomes was found to have the following characteristics: SG (30Â°C) 0.9724 and ND (30Â°C) 1.5002, and to contain d-alpha-pinene 1.5 per cent; d-camphene 3.5 per cent; cineol 9.6 per cent; a-camphor 4.2 per cent; d-borneol 1.5 per cent; sesquiterpenes 10 per cent; sesquiterpene alcohols 48 per cent. Phytotoxic compounds have also been isolated, and three antibiotic agents have been identified, the most abundant being ethyl p-methoxycinnamate. An unidentified toxin has been found in impure starch. In the usual process for preparing starch very thorough washing is employed, until the product is white: in this treatment most of the protein is removed (residual content about 10 g/kg) and most of the toxin. Less thoroughly prepared starch, containing 155 g protein/kg, and meal (containing 320 g protein/kg) was highly toxic to rats and chicks. It is not known whether the toxin is chemically associated with the protein or whether it is separately removed along with the protein during the starch purification process.
Starch - the rhizomes are shredded into a pulp and steeped for 24 hours in ten times their volume of water, with frequent stirring. The starch slurry is filtered off, repeatedly washed with pure water, then centrifuged and dried at 50Â°C. The recovery of starch is about 83 per cent and by treatment with dilute sulphuric acid or alkali during the washing process, a starch of approximately 94 per cent purity may be obtained.
It is generally considered that production of shoti for utilisation as an industrial source of starch is not likely to be economically viable because of the low yield obtained.
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