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Post Harvesting

Post Harvesting : 

The processing of turmeric consists of four stages:

Curing: 
Fingers are separated from mother rhizomes. Mother rhizomes are usually kept as seed material. The fresh turmeric is cured for obtaining dry turmeric. Curing involves boiling of fresh rhizomes in water and drying in the sun. The traditional method of curing is as follows:

The cleaned rhizomes are boiled in copper or galvanized iron or earthen vessels with water just enough to soak them. Boiling is stopped when froth comes out and white fumes appear jigging out a typical odor. The boiling lasts for 45-60 minutes when the rhizomes are soft. The stage at which boiling is stopped largely influences the color and the aroma of the final product. Over cooking spoils the color of the final product while under-cooking renders the dried product brittle.

The improved scientific method of curing turmeric is as follows: 
The cleaned fingers / mother rhizomes are taken in perforated trough made of GI or MS sheet with extended parallel handle. The perforated trough containing raw turmeric are then immersed in a pan of water which can hold 3-4 troughs at the same time. Boil it till the fingers / mother rhizomes become soft. The cooked turmeric is taken out of the pan by lifting the trough and draining the water into pan itself. The same hot water in the pan can be used for boiling next set of raw turmeric. The cooking of turmeric is to be done with in 2-3 days of harvest.

The rhizomes may also be placed in baskets with perforated bottom and sides and dipped in coveted tanks when the quantity is large or may be put directly into the vessels when the quantity is small. The mother rhizomes and fingers are generally cured separately.

Drying: 
The cooked fingers are dried in the sun by spreading in 5-7 cm thick layers on bamboo mats or drying floor. A thinner layer is not desirable as the color of the dried product may be adversely affected. During night time, the material should be heaped or covered. 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 600 C is also found to give a satisfactory product. The yield of dry turmeric varies from 20-30 % depending upon the variety and location where the crop is grown.

Polishing: 
Dried turmeric has a poor appearance and rough dull color outside the surface with scales and root bits. The appearance is improved by smoothening and polishing the outer surface by manual or mechanical rubbing.

Manual polishing consists of rubbing the dried turmeric fingers on a hard surface or trampling them under feet wrapped with gunny bags. The improved method is by using hand operated barrel or drum mounted on a central axis, the sides of which are made of expanded metal mesh. When the drum is filled with turmeric and rotated, polishing is affected by abrasion of the surface against the mesh as well as by mutual rubbing against each other as they roll inside the drum. The turmeric is also polished in power operated drums. The yield of polished turmeric from the raw material varies from 12-25 %. 

Coloring: 
The color of the turmeric always attracts the buyers. In order to impart attractive yellow color, turmeric suspension in water is added to the polishing drum in the last 10 minutes. When the rhizomes are uniformly coated with suspension, they may be dried in the sun.

After polishing, it should be kept in clean sacks and stored over wooden pallets in stores. Stores should be clean, free from infestation of pests, spiders and harborage of rodents. Pesticides should not be applied on the dried / polished turmeric to prevent storage pests.

Storage of Seed Turmeric: 
The seed rhizomes are selected free from insect pest and diseases. The seed material is harvested in dry weather and stored in a pit of 1 metre deep and 0.5 metre wide in size. The seed rhizomes are dried in shade before storing. The bottom of pit should be filled with 20 cm dry sand and 10 cm perfectly dried grasses before filling the seed rhizomes. The filled pits should be covered with dry grasses and dry sand at top. The pits should be under shade or under thatched roof to protect the rhizomes from rain and water etc.