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Agriculture > Spices > Turmeric (Curcuma longa)

Crop Management

Harvesting & Storage

Harvesting

Depending upon the variety, the crop becomes ready for harvest in 7-9 months after planting during January-March. Early varieties mature in 7-8 months, medium varieties in 8-9 months and late varieties after 9 months. The crop is ready for harvesting when the leaves turn yellow and start drying up. The land is ploughed and the rhizomes are gathered by hand picking or the clumps are carefully lifted with a spade.  The harvested rhizomes are cleared of mud and other extraneous matter adhering to them. The yield per hectare comes to 20,000 to 22,000 kilograms of green turmeric. Some of the high-yielding selections developed have recorded a yield of 35,000 of green turmeric per hectare.

Quality of cured turmeric is assessed on

  • The pigment (curcumin) content
  • The organoleptic character
  • The general appearance
  • Size and physical form of rhizome

Hence proper care is exercised while taking up processing the material.

Packaging

Whole Turmeric

  • Well-cured and dried turmeric is generally packed in double burlap new gunny bags which are properly fumigated prior to packaging.

Turmeric Powder

  • Humidity moisture relationship studies on ground turmeric have revealed that a moisture level of above 12.1% (dry-weight basis, DWB) is critical with respect to free-flow characteristics of the product.
  • Detail packaging studies have revealed that aluminium-foil laminate offers maximum protection against loss of volatile oil and ingress of moisture.
  • Double pouch of 300 MSAT cellophane glassine inside and 250 gauge low-density polyethylene outside offers adequate protection to the product over 135 days in different conditions of storage when initial moisture content of the product is about 9% (DWB).
  • Polyethylene pouches alone are inadequate to give desired protection against loss of volatile oil as nearly 60% of it is lost within 135 days.
  • Printing on the polyethylene pouches gets disfigured and smudged and pouches become sticky in bulk, turmeric powder is packed in fibre-board drums, multiwall bags and tin containers.
  • Turmeric oleoresin

This is obtained by solvent extraction of ground spice with organic solvents like acetone, ethylene dichloride and ethanol for 4-5 hours. It is orange red in colour. Oleoresin yield ranges from 7.9 to 10.4 % . one kg of oleoresin replaces 8 kg of ground spice.

Storage

Storage at Producers Level

  • Farmers can store cured turmeric for long if turmeric bags are stored in a pit. For this purpose, pits of 450 cm deep with 300 cm and 200 cm sides should be dug on raised ground.
  • The pits should be allowed to dry for a couple of days and sides and bottom should be padded with a thick layer of paddy straw or any such material.
  • Over the layer a date-mat is spread. After bags of turmeric are kept in the pit, they should be covered with a layer of straw or grass. It is then covered with soil.

Warehousing

  • Better and scientific storage in Central and State warehouses is recommended where prophylactic treatment and fumigation facilities too do exist for hygienic storage in a modern store at a nominal cost.

Control of Insect Infestation

  • Disinfestation of spices and spice powders may be achieved by heat, as insects in all stages succumb to exposure at 60°C for 5 to 10 min.
  • However, due to insulating effect of solid spice and also of powder, the exposure time and temperature required for effective killing of embedded insects leads to loss of quality.
  • Steam at 50 to 75 psi may be used to use temperature of vaults quickly to 85 to 95° C, and these treatments disinfect 45.3 kg bags of powdered spice in 24 hr.
  • Cost of treatment and loss of quality limit use of this method. Infrared treatment of spice passing through a rotating inclined metal tube has been suggested, but specific studies on the feasibility of the treatment for turmeric are not available.
  • Fumigation with suitable chemicals has been developed into quick, effective and economic disinfestation procedure.
  • Sulphurdioxide from burning sulphur in sealed warehouses has traditionally been used in developing countries, but has been almost given up in favour of other gaseous fumigants which are easier to use, are more effective and have minimum effect on the quality of spices.
  • The lethal doses of a number of fumigants for adult insects have been determined, and allowing for sorption of gases by commodities and loss by leakage, a working dosage of 4 to 5 times the lethal dosage is recommended.
  • For achieving 100% disinfestation, the maintenance of an effective concentration and exposure period is necessary.
  • Vital considerations other than achieving sterility are permissible levels of fumigant residues, interaction products, and their effect on flavour quality of spice.
  • Phosphine and hydrogen cyanide are highly effective at low doses of a few milligrams per line, but handling problems and residue tolerance levels limit their use in spice-growing developing countries.
  • Normal airing at the end of fumigation, processing and cooking releases unreacted fumigant to, less than a few ppm at this concentration, the risk is insignificant.
  • Recommended maximum levels of methyl bromide vary from 20 to 100 ppm for different foods at the point of retail distribution.
  • With these organic bromide fumigants, water soluble inorganic bromides are formed as residues in the treated food. Their level is indicative of the level of bromine-containing fumigants originally used.
  • To prevent excessive use of brominated hydrocarbon fumigants, a tolerance of 50 ppm of bromide ion has been recommended for cereals and flours.
  • Regarding spices whose daily intake is small, a level of 400 ppm is recommended by the FDA in the USA while a tolerance level of 100 ppm is specified by the PFA in India.
  • Residues of inorganic bromide from fumigation of turmeric, using 64 mg of ethylene dibromide for 96 h or methyl bromide for 48 h, were of the order of only 26 ppm, well within the conservative limits fixed even for cereals.

Source: http://www.ikisan.com

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