Turmeric powder processing is vigorous to both the development of the appealing yellow colour and to enhance the characteristic aroma of this wonder spice. The process is elucidated below:

  • The rhizomes and bulbs are boiled in water for to hours until froth and fumes appear.
  • They are drained and sun baked for 10-15 days
  • When turmeric fingers produce a metallic sound on being broken, they are said to be cured
  • They are cleaned and mechanically polished in a drum
  • They are then powdered and packed for sale.

The storage of the seeds is a critical part of the curing process. The rhizomes are detached and dried in the shade for 4-6 days after cleaning them. They are then preserved in underground pits, locally known as kattir.

Turmeric Powder Processing

Curing

Fresh turmeric is cured for getting dry turmeric.  The fingers are detached from mother rhizomes.  Mother rhizomes are usually kept as seed material.  Turmeric powder processing involves boiling of fresh rhizomes in water and drying in the sun.  In the traditional way of turmeric processing, the cleansed rhizomes are boiled in water just enough to immerse them.  Boiling is stopped when froth comes out and white fumes seem giving out a typical smell.  The boiling should for 45-60 minutes when the rhizomes become soft.  The stage at which boiling is stopped largely influences the colour and fragrance of the last product.  Over cooking plunders the colour of the concluding product while under-cooking renders the dried product brittle.

Drying

The cooked fingers are dried in the sun by spreading them in 5-7 cm dense layers on bamboo carpets or drying floor.  A thinner layer is not pleasing, as the colour of the dried product may be adversely affected.  During night time, the rhizomes should be heaped or enclosed with material, which provides ventilation.  It may take 10-15 days for the rhizomes to become completely dry.  Artificial drying, using cross-flow hot air at a maximum temperature of 60°C also gives a satisfactory product.  In the case of sliced turmeric, artificial drying has clear advantages in giving a brighter coloured product than sun drying which manages to undergo surface bleaching.  The harvest of the dry product differs from 10-30% depending upon the variety and the location where the crop is grown.

Polishing

Dried turmeric has a poor look and a rough dull outside surface with scales and root bits.  The appearance is improved by smoothening and polishing the outer surface by manual or mechanical rubbing.  Manual polishing contains of rubbing the dried turmeric fingers on a firm surface.  The better way is by using a hand operated barrel or drum mounted on a central axis, the sides of which are made of extended metal mesh.  When the drum occupied with turmeric is alternated, polishing is effected by abrasion of the surface against the mesh as well as by mutual rubbing against each other as they roll in the innermost the drum.  Turmeric is also polished in power-operated barrels.  The yield of polished turmeric from the raw material varies from 15-25%.

Colouring

The colour of the handled turmeric effects the price of the produce.  For an appealing product,turmeric powder processing (mixed with little water) may be sprinkled during the last phase of polishing.